AP130 Vs Apomax
ToddG18522
>very impressed with the APOMAX on the >planets
Dave, when did you get it, wasn't jupiter already nearing it's conjunction of
the sun when you got the apomax?
tg
Dave Novoselsky
now (the scope) but went to a friend close by so still available for the
'mooch look' when he is in the mood to be nice. Dave
"ToddG18522" <toddg...@aol.com> wrote in message
news:20000522064635...@ng-fa1.aol.com...
Allister
If you have the chance to buy an Apomax, buy it! There are only
something like 24 out there so you may be staring at a once in a
lifetime chance (by comparision there were around 65 TV140s made)
I've had one opportunity to use the Apomax since I purchased it (rain,
rain, rain) and that night was seriously cloudy with really poor
seeing). Looking at the moon was just like looking at the bottom of a
fast moving stream.
The Apomax is not really as big as I've heard folks describe it. 35
lbs and it works fine on a Losmandy G11. A 1/2 pier extension will be
in my future but it wil also work without one if you are willing to
sit on the ground.
I won't attempt to describe the fit-n-finish but will post some photos
at www.cloudynights by the end of today so folks can get a sense of
what we are discussing. Full review won't be for quite some time but
I will put comments there as I learn more.
I didn't star test the scope as I'm simply not experienced enough to
interpet a high-end APO star test. One of those present that night is
an experienced star tester and thought the star test was as good as
he's ever seen even though he was testing through soup. He was one of
the AP owners that night and I kept having to pry him away from the
eyepiece to get some viewing myself :}
As for the lunar comparision the seeing was such soup it would
probably be in error to make comments just yet. We all agreed to get
together again in the near future and repeat the same comparision and
I will post any meaningful results here and at www.cloudynights.com.
Hope this helps.
Allister
a...@ais.net
Rich N.
you could see an improvement in the image and
the Apomax will require a larger mount to be as
stable as the AP.
Rich
Buddy In NY wrote in message <8g9nu4$n3e$1...@slb2.atl.mindspring.net>...
>Ive got a chance to aquire a Apomax,,pretty cool huh. I own a Ap130,
>thinking of trading it with some cash for the Apomax,,,,,whadda think!!!
>Id like to here from some owners who have done side by side comparisons
>
>
>--
> ~ Buddy In N.Y.~
>~Urban Guerrila Astronomy~
>
>
Dave Novoselsky
130 f/8.3s are a tick better. I am waiting for the weather to clear and the
seeing to settle down so Allister and I and others can (hopefully) do a 4"
through 6" shoot out, using my TMB 4", his new Apomax, the two TV 140s that
reside in this area, several 5 and 6" APs and a passle of Taks. Now if we
can persuade our friend out West with the Zeiss APQ 4, 5 and 6 to come, and
Tom Back has my 7" ready, it might make a REAL interesting article -- and
then through in some of the Zambuto mirror Starmasters, a Tak Schmidt and
Mewlon, the 'planet killer world series'!!!! Coming this summer? We will
see. Dave
"Rich N." <rnapo*remove*@znet.com> wrote in message
news:siil6t...@corp.supernews.com...
John J. Kasianowicz
I'd love to read a critical review of a Thomas Back 7" APO.
Best,
John
Dave Novoselsky wrote:
[snip]
Mark
First of all, about the production numbers of the Apomax.
I've heard a couple of folks say there were 27, and now it's stated
there's 24.
In a personal face to face conversation with Fred about 2-1/2 years ago,
Fred himself stated that he was a bit unsure of the actual numbers
produced, but if memory serves me correctly Fred claimed at that time
that there were closer to 35-40 made.
This was some time before the production end also I believe.
Second, I'd like to comment from what I know about the Apomax' optical
quality, design, and glasses used.
I am not aware that Ohara FPL-52 was an inferior ED glass.
The AP EDT line used this very same glass.
The new TMB Flourostar SD scopes are probably using a very close Russian
equivalent to Ohara FPL-52.
Probably, the limiting factor with FPL-52 will be the Design, the Focal
Ratio, and the Optician's abilities. From what I know, it is a very
good ED glass.
The Apomax lens design was by Dr. R Buchroeder.
It would probably be correct to state, that yes, the Apomax was not the
most optimal design. Fred recognized this, but followed though with the
production to the best of his abilities, and expertise.
Even so, there is something about the Apomax' optics that are just
astounding, and magical.
It can most likely be attested to the care of figuring, and
making/assembly of the lens sets.
To me, views through the Apomax appear to be views that larger
refractors provide.
I could go on, and on, but I will end here.
Also, on a fairly accurate bathroom scale, I come up with 31 lbs. for my
Apomax.
Mark
Rich N.
John J. Kasianowicz wrote in message <8gd3ah$lgl$1...@bob.news.rcn.net>...
>Have you ever seen false color in an A-P 155 mm f/7 EDF APO?.
>
><samw...@my-deja.com> wrote:
>[snip]
>> At f/12, even with inferior glass and probably an inferior
>> design, it has shown better color correction and figure than a recent
>> AP155EDF (Not my opinion, but a talented star tester non the less.)
Since he is talking about a "talented star tester" I assume
he (the tester) isn't talking about the in focus image.
Rich
Rich N.
True, the AP latest 130mm f/8.35 should be a
little better. I hope Roland will make more. However,
I think the earlier EDT AP 130mm f/8 or the current
AP 130mm f/6 are so good that I would be surprised
if a 5" Apomax is any better (if quite as good). At least,
IMHO, it would be difficult to see a difference. I think the
difference wouldn't be worth the extra bulk of the f/12 Apomax.
I sincerely hope you can have your shoot out. I would be
very interested in reading your report. A big difficulty having
a shoot out is is finding people willing to put their scopes
on the line to be judged.
Maybe you can hold off your shoot out long enough to
be able to use Jupiter as a target.
Rich
Dave Novoselsky wrote in message <8gcot7$bq4$1...@slb7.atl.mindspring.net>...
>But which AP 5" The AP 130 f/6 is an incredible scope. But the latest AP
>130 f/8.3s are a tick better. I am waiting for the weather to clear and
the
>seeing to settle down so Allister and I and others can (hopefully) do a 4"
>through 6" shoot out, using my TMB 4", his new Apomax, the two TV 140s that
>reside in this area, several 5 and 6" APs and a passle of Taks. Now if we
>can persuade our friend out West with the Zeiss APQ 4, 5 and 6 to come, and
>Tom Back has my 7" ready, it might make a REAL interesting article -- and
>then through in some of the Zambuto mirror Starmasters, a Tak Schmidt and
>Mewlon, the 'planet killer world series'!!!! Coming this summer? We will
>see. Dave
samw...@my-deja.com
"Rich N." <rnapo*remove*@znet.com> wrote:
> I would keep the AP 130. I would be surprised if
> you could see an improvement in the image and
> the Apomax will require a larger mount to be as
> stable as the AP.
Interesting delema. My APOMAX has the best figured optics of all my
scopes. At f/12, even with inferior glass and probably an inferior
design, it has shown better color correction and figure than a recent
AP155EDF (Not my opinion, but a talented star tester non the less.)
The 130 drops right between my Traveler EDF and 155EDF. My brother has
the 130EDF so I have judged all three in comparison.
In this case I would agree with Rich. The 130 on a G-11 is rock solid.
The APOMAX would push the mount to the edge. In fact my GM 200 is a
far better mount for that scope.
I too would keep the 130, unless I could afford them both;-}
Stew
>
Sent via Deja.com http://www.deja.com/
Before you buy.
samw...@my-deja.com
Blandp1
Hash: SHA1
>The Apomax was built by Fred Mrozek, a truly gifted optician
>and optical designer here in Northern Illinois. Every one that
>I am aware of had optics that were hand made by Fred lavishing
>his not inconsiderable skill on each one til they were as
>perfect as can be. The mechanicals are just as good, and the
>focuser a thing of rare beauty. If you can find one, grab with
>both
Yes, the mass produced machine made AP's just can't compete. I
think that AP spends, what, 30 seconds figuring each lens.
Roland Christen is usually out of the country in Germany or
elsewhere chasing eclipses or good beer or fast cars and spends
almost no time at the factory giving attention to grinding
lenses.
I understand that the mechanics of the AP scopes are made on
1890's vintage lathes that are powered by water wheels!
:-)
Seriously, I would doubt that any improvment in the images
between the APOMAX and 130EDF (f/6) will be visible. Any such
theoretical improvement will most likely be swamped by the
decreased stability of the APOMAX unless it is on a seriously
big mount, or the 130EDF is on a far too small mount. I'd say
keep your 130EDF.
Philip J. Blanda III
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John J. Kasianowicz
samw...@my-deja.com
"John J. Kasianowicz" <sur...@erols.com> wrote:
> Have you ever seen false color in an A-P 155 mm f/7 EDF APO?.
Not in any focused image, but a little violet during the star test.
samw...@my-deja.com
MarkDa...@webtv.net (Mark) wrote:
> Second, I'd like to comment from what I know about the Apomax'
optical
> quality, design, and glasses used.
> I am not aware that Ohara FPL-52 was an inferior ED glass.
Mark, don't get me wrong, I love my APOMAX. I was pointing out the
delema. The 130 is an another amazing AP effort. And FPL-52 is
inferior if you have to use it in a design compared to FPL-53. The
original Buchroeder design did have a flaw according to Fred. Yet at
f/12, these are inconsiquential (the 1/12 wave PV helps). I
personnally wouldn't give up this lens for anything. And it would be
the last telescope I sell (well maybe before my Questars;-}
Actually not mentioned here except in a sidelight is the best
compromise between the two. Buy the AP130 f/8.3. This gem is the
heart of the 155EDF triplet in 130mm. Benefit of better focus range as
well as remaining compact and G-11 mountable. I have made these same
use tradeoffs at 100mm. I have a Traveler at f/5.9, A Tak FC100 at
f/8, a Pentax 100 at f/12, and a 4" Unitron at f/15. The Tak is the
best all around scope, period!
> The AP EDT line used this very same glass.
And they are not up to the EDF's performance, from everything I've read
here and in resale value.
Stew
lude...@my-deja.com
> Mark, don't get me wrong, I love my APOMAX. I was pointing out the
> delema. The 130 is an another amazing AP effort. And FPL-52 is
> inferior if you have to use it in a design compared to FPL-53.
Hi Stew,
why you think, that FPL52 is inferior to FPL53 ? All depents only with
which glases you mix it. For sample, the first version of ARIES 6"F/7.9
Triplet used a FPL 52 and the colorcorreection was visible better than
in a Tak FCT 150 and visible better than in a Zeiss APQ 150.
One optician using FPL 52 can design a better optic than another using
FPL 53.
If Aries would use FPL 53 instead of FPL 52 in this first design he
might bring out a better correction on his computer, but never for the
visual eye, because better than real colorfree is not necassary.
Another sample. take a look through an TMB 4"F/8 and tell me, if you
think, the colorcorrection can be made better. I beat you will answere,
no better cannot be.
best wishes
Markus
Dave Novoselsky
area, we should be able to assemble the array. Will it happen? I hope so,
and 'planet season' will be the best time to do it. Later. Davenews:sik6p5...@corp.supernews.com...
> >> you could see an improvement in the image and
> >> the Apomax will require a larger mount to be as
> >> stable as the AP.
> >>
Dave Novoselsky
in quality to an AP do some people jump up and howl? I owned the Apomax
before it went to Allister. I was extraordinarily impressed with it, but it
just didn't fit with my current plans (we are moving and I don't have the
space outside for such a long focal length scope.) Yes, Fred did lavish a
lot of effort on these scopes. And yes, they are superb. So are the 155
and 130f/6 APs that I own and enjoy (see my reviews at
www.cloudynights.com ) I think my APs are extraordinary scopes as well, and
I do not intend to part with them. I also now own a Televue TV 140 - yet
another 'keeper.' I have or have had several great Takahashi scopes, to say
nothing of an incredibly special TMB 100f/8, again, a 'keeper.' The Apomax
would have been a 'keeper' as well, except it had to go to preserve marital
harmony in a stressful time because of it was the longest scope in the
current stable, and it went to a friend who lives nearby and will hopefully
let me whine my way into looking through it when the planets return. So,
no, I didn't suggest by my comments on Fred's efforts that Roland is goofing
off by having the audacity to praise the work of someone else. The amount
of effort put into the AP scopes is self-evident by the outstanding results.
My 130 is recent production, and it is no 'less' of a product than older
APs. Thus, I think your comments are out of place. Roland has never said
he is the only man on Earth who is capable of making a world class
refractor. I have never heard him 'dump' on any other company nor has he
suggested that there is AP and nobody else. These type of comments seem to
come from people on this NG who will brook no comparasions between AP and
anything else on this planet. I think you do Roland a disservice by your
comments. Dave
"Blandp1" <bla...@aol.com> wrote in message
news:20000522225111...@ng-fh1.aol.com...
Allister
Thanks for the concrete information on the APOMAX. The 24 produced
was a number I heard from 3 seperate people and I assumed (always a
bad thing) that it was a correct number.
31lbs? Wow - my bathroom scale is weighing me light! Now that's the
kind of news I like to read in the morning. It's Big Macs for lunch
today.
I'd love to talk to you about this further. Also, please go on and
on. I for one am very interested in your opinions on the APOMAX and
its design and performance.
Thanks
Allister
a...@ais.net
>Hi, I'd like to comment some here, if you folks don't mind.
>First of all, about the production numbers of the Apomax.
>I've heard a couple of folks say there were 27, and now it's stated
>there's 24.
>In a personal face to face conversation with Fred about 2-1/2 years ago,
>Fred himself stated that he was a bit unsure of the actual numbers
>produced, but if memory serves me correctly Fred claimed at that time
>that there were closer to 35-40 made.
>This was some time before the production end also I believe.
>Second, I'd like to comment from what I know about the Apomax' optical
>quality, design, and glasses used.
>I am not aware that Ohara FPL-52 was an inferior ED glass.
>The AP EDT line used this very same glass.
lude...@my-deja.com
a...@voyager.net (Allister) wrote:
Hi Allister,
I did cut my Apomax tube for 8", now i am able to use binoviwer without
barlow, use a 4"x 5" fieldflattner with off axis guider and any other
stuff.
With the big focuser and long focus travel and extension I can reach
now easily with any accessories the focus. The scope looks now much
nicer, where it is real 200 mm shorter than before.
Markus
Sketcher
> "John J. Kasianowicz" <sur...@erols.com> wrote:
>> Have you ever seen false color in an A-P 155 mm f/7 EDF APO?.
>
>Not in any focused image, but a little violet during the star test.
Seeing color in a highly magnified star image, whether the image is in
focus or out of focus (depending upon the specific colors and their
distribution within the image), reveals little beyond the apparent
brightness of the star, the color sensitivity of the observer's eye,
and the fact that different wavelengths of light produce different
sized images.
I've seen colors in the out of focus diffraction patterns of my 130
EDF as well as with my 25cm Newtonian, but I'm not at all bothered by
either. Few people would consider designing a telescope expressly for
the purpose of defeating the "apparent" laws of physics. Colors are
the norm in highly magnified out of focus stellar images -- even when
a totally "color-free" optical system is used.
Rich N.
samw...@my-deja.com wrote in message <8ge23g$f78$1...@nnrp1.deja.com>...
-snip
>> The AP EDT line used this very same glass.
>
>here and in resale value.
>
>Stew
Hi Stew,
The 180EDT, 155EDT and 130EDT were all made in
longer focal ratios than the EDFs. I believe the f/7 and
f/6 EDF needed to use FPL 53 to achieve the color correction
of the longer fl EDTs using FPL52. Maybe Roland or others
can help here. I don't think the performance is less in a
130mm f/8 EDT than a 130mm f/6 EDF.
The latest AP 130 f/8.35, I believe, uses FPL53 and should
be a little better than the earlier AP 130mm f/8s with FPL52.
Rich
Mark
years in a row, at Astrofest. (Probably 1000 scopes going head to head)
My Apomax has surely "held it's own" every year out there (97-98-99)
Naturally, the Apomax has it's shortcomings in it's long F-Ratio.
Photographing faint fuzzies would be difficult with film emulsions, due
to long exposures. It's not impossible though.
This was not what the Apomax was designed, or intended to do.
With it's 4 color crossings, and it's correction from Blue-violet, into
the near IR, it was suited for CCD, and visual use.
I'm not really highly versed in optical terms, but I remember Fred
saying that if the Apomax had of been "Nulled in the visual wavelengths,
the P-V figures would have been twice as high, due to the smoothness of
the lenses.
Folks such as Brian Murphy, Tom Back, Bob Luffel, Stew, Markus and many
others will personally attest to the fact that the 5.2' Apomax is the
finest 5" they have ever viewed through.
I personally do not have quite the experience of those I have mentioned
here. I have only personally owned 2 refractors in my life, the Apomax,
and the AP Traveler EDFS. both will go to the grave with me, as I love
both of them.
I do love refractors immensly, I just wish, and pray that a spare 200K
would fall in my lap! I'd have one of each! (AP, Tak Zeiss, HTPO!)
Clear skies, Mark
RAnder3127
>delema. The 130 is an another amazing AP effort. And FPL-52 is
>inferior if you have to use it in a design compared to FPL-53.
Do you really think an F12 design with
FPL-52 is "inferior" to an F6 with FPL53?
(We might as well deal with those as
there have been no F12 refractors made
using FPL53, I guess)
I honestly would think the F12 would
still have an edge in overall aberration
correction. The F12 of those scopes
could easily explain the quality relative
to the faster APs. Unless the lens figuring
is better.
-Rich
"I resent having to foot the bill for FOUR catalytic converters
on my car when I see diesel trucks puking huge volumes of
black soot into the air when they accellerate. It's time to
filter that crap."
RAnder3127
>nicer, where it is real 200 mm shorter than before.
I've often wondered if the Unitron 4"
F15 had been sectional (halved with a
bayonet mouting) if their market wouldn't
have eroded quite so much. But then
I remember the SCT and large aperture scopes killed them.
RAnder3127
combative, so don't take it as
such, because the answer you give
goes to the core of why a person would
use one very similar scope over another.
How can you justify keeping both the
AP130 (apart from it's value as an
appreciating asset)and the TeleVue 140mm? It would seem the
TeleVue offers all the positives and is
compact as well. Under what observing
conditions would the AP be chosen over
the TeleVue or vice-versa? I'm thinking the
AP has some attribute the TeleVue doesn't, but I just don't know what that
would be. It would be nice to be in that
position, but from what I can tell, choosing
a scope to observe with might require
a coin toss!
Brian Murphy
> But then
> I remember the SCT and large aperture scopes killed them.
> -Rich
Rich,
What does this mean?
BPM
Brian Murphy
(as recently as 1998) and didn't have enough takers to make it viable. What
has changed since then?
Brian Murphy
Mark <MarkDa...@webtv.net> wrote in message
news:5502-392...@storefull-222.iap.bryant.webtv.net...
Dave Novoselsky
understand the nuances of astrophotography. Your 130 AP appealled to my
interests in getting the best combination of size, that is, size of scope
and optics, ease of use, and quality of optics and mechanics. It fit the
bill. The TV 140 is almost the same size, although a much different design.
As I said to Rich, I intend to keep them both, and think you and Al should
both be proud of your respective creations. My compliments to both of you.
Dave Novoselsky
"Chris1011" <chri...@aol.com> wrote in message
news:20000523215247...@ng-cl1.aol.com...
> >> I'm thinking the
> AP has some attribute the TeleVue doesn't, but I just don't know what that
>
> Visually, the AP probably does not, but the 130F6 EDF was designed for
wide
> field 6x7 astro-photography, something the TV cannot do. But then, nobody
on
> this newsgroup seems to need that, so it's a moot point.
>
> Roland Christen
> ASTRO-PHYSICS
Dave Novoselsky
Apomax comments 100%. (Take care of my ex-Apomax, Allister, I may want it
back one day.) Dave
Brian Murphy
I believe all it takes for most amateurs to see color in an achromat, is for
them to view a bright object through it, and compare it "side-by-side" with
a good APO. I'm sure your vast star party experience bears this out. If
there were more good APO's which were affordable, and readily available to
the "masses", I think the IQ (Inherent color recognition Quotient) of most
amateurs would surprise you.
Brian Murphy
>Chris1011 <chri...@aol.com> wrote in message
...
> This allows some companies to offer ED Apo lenses at a lower >price, and
since today, a lot of amateurs can't see color errors even >in basic fast
achromats, it sounds like a winning concept.
Dave Novoselsky
physical size, and the difference in ap not all that great. Perhaps, and I
am not being funny, some of us just like to collect really outstanding
refractors. I love the AP. The Televue is just, well again here goes that
word, cute and neat. I also doubt if Al Nagler will ever build something
quite like it again. A tour de force, if I may. If I had to choose, would
I give up one? Sure. Which one. Don't have to make that decision now, so
I won't. Valid question, and I ask that you accept the answer in the same
spirit. Davenews:20000523193954...@ng-ch1.aol.com...
> This is not meant to sound
> combative, so don't take it as
> such, because the answer you give
> goes to the core of why a person would
> use one very similar scope over another.
> How can you justify keeping both the
> AP130 (apart from it's value as an
> appreciating asset)and the TeleVue 140mm? It would seem the
> TeleVue offers all the positives and is
> compact as well. Under what observing
> conditions would the AP be chosen over
> AP has some attribute the TeleVue doesn't, but I just don't know what that
Rich N.
Rich
Chris1011 wrote in message <20000523214152...@ng-cl1.aol.com>...
>The latest 130 F8.35 does indeed use FPL53, but does not have significantly
>better color correction. It does, however, allow me to use the same tooling
as
>that used for the 155F7 lenses. Makes production easier.
>
>All our longer EDT triplets use FPL 52 as the ED element. With the proper
>mating crown glasses, this results in zero secondary spectrum. Lenses
faster
>than F8 require FPL53 in order to control sphero-chromatism. We call these
EDF
>lenses, although we did goof with some earlier Travelers which were named
EDT
>lenses but used FPL53. Basic color correction is the same in either case.
Both
>produce zero secondary spectrum. The difference between the two glasses is
the
>F ratio that can be achieved and how much the designer is willing to let
the
>sphero-chromatism hang out.
>
>The other way to control sphero-chromatism is to introduce a small amount
of
>secondary spectrum. In that case, less expensive ED glasses can be used to
make
>relatively fast near Apo lenses. This allows some companies to offer ED Apo
>lenses at a lower price, and since today, a lot of amateurs can't see color
>errors even in basic fast achromats, it sounds like a winning concept.
>Nevertheless, we probably will not offer this type of Apo, since we don't
have
>the production capacity.
>
>Roland Christen
>ASTRO-PHYSICS
>
Brian Murphy
sixties and early seventies.
BPM
RAnder3127 <rande...@aol.com> wrote in message
news:20000523230442...@ng-ch1.aol.com...
> >> But then
> >> I remember the SCT and large aperture scopes killed them.
> >> -Rich
> >
> >Rich,
> >
> >What does this mean?
>
> That Dobs and SCTs doomed the long
> refractor market. A market that used to
> dominate the telescope world, until about
> 1975.
Ocean779
>AP has some attribute the TeleVue doesn't, but I just don't know what that
>would be.
how about the ability to binoview w/o a barlow?
sean nolan
Chris1011
longer focal ratios than the EDFs. I believe the f/7 and
f/6 EDF needed to use FPL 53 to achieve the color correction
of the longer fl EDTs using FPL52. Maybe Roland or others
can help here. I don't think the performance is less in a
130mm f/8 EDT than a 130mm f/6 EDF.
The latest AP 130 f/8.35, I believe, uses FPL53 and should
be a little better than the earlier AP 130mm f/8s with FPL52.>>
The latest 130 F8.35 does indeed use FPL53, but does not have significantly
Chris1011
AP has some attribute the TeleVue doesn't, but I just don't know what that
Chris1011
I honestly would think the F12 would
still have an edge in overall aberration
correction. The F12 of those scopes
could easily explain the quality relative
to the faster APs. Unless the lens figuring>>
An F12 always has an advantage over an F6, no matter how cheap the ED glass
that is used. Long focal lengths are very forgiving to small figuring errors
(easier to make), or radii errors, or even glass variations. It is almost
impossible to make a bad F12 lens. Making an F10 lens is quite a bit harder,
making an F8 lens is harder yet by a significant amount, and an F6 lens
requires very much more work to make it look good. It is very easy in a half
dozen ways to make a very bad looking F6 Apo lens.
Meade would have a truly world class 5" refractor with their doublet design, if
it were F12 or F14, rather than F9.
Roland Christen
ASTRO-PHYSICS
Don Holcombe
>
> The latest 130 F8.35 does indeed use FPL53, but does not have
significantly
> better color correction. It does, however, allow me to use the same
tooling as
> that used for the 155F7 lenses. Makes production easier.
>
> All our longer EDT triplets use FPL 52 as the ED element. With the proper
> mating crown glasses, this results in zero secondary spectrum. Lenses
faster
> than F8 require FPL53 in order to control sphero-chromatism. We call these
EDF
> lenses, although we did goof with some earlier Travelers which were named
EDT
> lenses but used FPL53. Basic color correction is the same in either case.
Both
> produce zero secondary spectrum. The difference between the two glasses is
the
> F ratio that can be achieved and how much the designer is willing to let
the
> sphero-chromatism hang out.
>
As I am on the long list for a 130 f/8.35 (and f/6) are you considering
another production run in the future? I've heard pro and con, just
curious. If my number ever comes up I'll take either but the f/8 is sweet.
Regards,
Don Holcombe
Vahe Sahakian
> longer focal ratios than the EDFs. I believe the f/7 and
> f/6 EDF needed to use FPL 53 to achieve the color correction
> of the longer fl EDTs using FPL52. Maybe Roland or others
> can help here. I don't think the performance is less in a
> 130mm f/8 EDT than a 130mm f/6 EDF.
>
> The latest AP 130 f/8.35, I believe, uses FPL53 and should
> be a little better than the earlier AP 130mm f/8s with FPL52.
I have compared my 155mm f/9 EDT (1993) with one of the more recent
155mm f/7's and the color correction in the older one is at least as
good if not better than the f/7's despite of the FPL-52 vs FPL-53.
I have also heard that AP used FPL-53 in the last runs of smaller EDT's,
this according to TMBack history of AP lenses.
Thanks,
Vahe
RAnder3127
>am not being funny, some of us just like to collect really outstanding
>refractors. I love the AP. The Televue is just, well again here goes that
>word, cute and neat.
Yes, I know one guy who has a hundred
or so brass microscopes of varying vintages. He even uses them, but not
all of them, all the time. The most telescopes I ever had at one time was
nine. The breakdown of usage was
something like, Ultima 11 70% of the
time, Vernonscope 94mm around 20% of
the time, and the rest the remainder.
I was actually down to one for about a week, then it went to two, and now
it sits at four, not counting some really
small refractors. I can probably make use of all four profitably, but the time
is still going to be divided amongst them.
I think the interesting thing is that these
scopes and the majority of the 150 or so
I've owned will be here for hundreds of years, maybe thousands, barring any
catastrophe that wrecks them.
RAnder3127
>(as recently as 1998) and didn't have enough takers to make it viable. What
>has changed since then?
There is more money out there. The apo
market has grown and perhaps (though
I don't think so) people are willing to tolerate a bit longer focal length now
that
the novelty of ultra-short refractors has
worn off a bit? I would still expect F12
5" scopes to be harder to sell than F6-8
scopes, especially since you have to double your mount price to hold it as
well.
RAnder3127
>> I remember the SCT and large aperture scopes killed them.
>> -Rich
>
>Rich,
>
>What does this mean?
That Dobs and SCTs doomed the long
refractor market. A market that used to
dominate the telescope world, until about
1975.
RAnder3127
>if
>it were F12 or F14, rather than F9.
But then they'd have to use their
750 mount to hold it, and it costs
alot more than the barely adequite
650.
RAnder3127
>secondary spectrum. In that case, less expensive ED glasses can be used to
>make
>relatively fast near Apo lenses. This allows some companies to offer ED Apo
But say your ultimate goal is seeing
the greatest amount of detail on an
target. Isn't sphero-chromatism a
"worse" problem than chromatic aberration?
John J. Kasianowicz
mistaken, Roland optimized the color correction of his EDF APOs for the
in-focus image.
I suppose A-P could make another version of their APOs for the folks who
prefer the color-correction applied to an out-of-focus plane. ~8^)
Rich N. wrote:
> Since he is talking about a "talented star tester" I assume
> he (the tester) isn't talking about the in focus image.
TMBack
>Folks such as Brian Murphy, Tom Back, Bob Luffel,
>Stew, Markus and many others will personally attest
>to the fact that the 5.2' Apomax is the finest 5" they
>have ever viewed through.
Yes, I did say that, but it was before I received my
1/22 wave P-V Astro-Physics 5.1" f/8.35 EDT (F) apo.
The lens is awesome, and I'm sure it performs at the
"APOMAX" level.
>I do love refractors immensly, I just wish, and pray that
>a spare 200K would fall in my lap! I'd have one of each!
>(AP, Tak Zeiss, HTPO!)
So Mark, you have changed your mind about a fine,
large TMB Fluorostar refractor?
Thomas Back
TMB Optical
samw...@my-deja.com
"Rich N." <rnapo*remove*@znet.com> wrote:
>
> The 180EDT, 155EDT and 130EDT were all made in
> longer focal ratios than the EDFs. I believe the f/7 and
> f/6 EDF needed to use FPL 53 to achieve the color correction
> of the longer fl EDTs using FPL52. Maybe Roland or others
> can help here. I don't think the performance is less in a
> 130mm f/8 EDT than a 130mm f/6 EDF.
>
> The latest AP 130 f/8.35, I believe, uses FPL53 and should
> be a little better than the earlier AP 130mm f/8s with FPL52.
Rich, this doesn't change my perspective. If Roland can achieve
similar correction at a shorter focal length, then the FPL53 is a more
versatile glass. I believe that FPL52 becomes then inferior to it as
you can't achieve the EDF level of correction at f/6-7 with FPL52. Yet
you can design an awesome APO at f/8-9 (EDT) with FPL53. The 130 f/8.3
is the perfect example. Even Roland has commented that it is a
production issue to build this scope instead of the 130 f/8 EDT as he
can use his 155EDF tooling.
I am sure that there is not a single one of us that wouldn't want
Thomas Back's 180 EDT. Yet in all the other EDT's I've seen for sale,
they don't have the price support of the EDF's. The market perceives
them to be of less value, maybe only because they are a little slower
and not because they use FPL52.
And if we go back to what the original poster wanted out of this
thread, even you have baised his decision toward the faster of the
two. All I have been trying to say is that the APOMAX is unbeaten by
any other scope I own. And to make use of that I have to put up with
its length and mount restrictions. I can tell you that the 155EDF is a
whole bunch nicer to throw up on the mount than the APOMAX. Hence my
agreement with you that the original poster should keep his AP130. My
brother feels his will probably be his last scope, end of search.
Stew
Sent via Deja.com http://www.deja.com/
Before you buy.
samw...@my-deja.com
"John J. Kasianowicz" <sur...@erols.com> wrote:
> That is indeed what I would thought he meant. However, if I am not
> mistaken, Roland optimized the color correction of his EDF APOs for
the
> in-focus image.
I do most of my viewing in focus as well, however all fun aside, there
are serious evaluations going on all the time between folks that spend
many thousands on OTA's. Roland, and any other manufacturer out there,
certainly knows that their scopes will be tested. The smallest
variations, that can best be detected in the out-of-focus images, are
large issues to many of us. Issues that mean big bucks to
manufacturers. There are more than a few on this list that refuse to
settle for less than the best. Each and every one star tests and makes
use of those out-of-focus images. They may accept tradeoffs such as
focal length, or cost (I got to 8" with an achromat at f/12 cause it
was cheap, yet the optics are made by a hobbyist that put more time
into them than any manufacturer could or would!), whatever; but I am
pleased and consider myself lucky that I own an APOMAX. It has the
best optics I own. It might have been easier to get right because it
is f/12, but I really don't care about that, the figure is better, the
color correction is better. It is simply the best! I would put it's
images against any other 5" at 24X (65mm Leitz 90 deg, 3.7 deg field,
5.4mm ep) to 634X (2.5mm Vixen Lanthuim) and feel confident that it
would come out a winner under the most critical evaluation. Heck, I
probably feel as good about this scope as Thomas Back feels about his
180 EDT!
samw...@my-deja.com
tmb...@aol.com (TMBack) wrote:
> Yes, I did say that, but it was before I received my
> 1/22 wave P-V Astro-Physics 5.1" f/8.35 EDT (F) apo.
> The lens is awesome, and I'm sure it performs at the
> "APOMAX" level.
Hi Thomas,
I wondered when you would say something about this new 130. With
numbers like the above, I think you should beat my APOMAX, (at least in
those out-of-focus evaluations ;-} Will you have this at Astrofest
this year?
From a design standpoint, how much does removing the outside 12.5mm of
the 155EDF lens set improve the overall image quality, in general?
Enjoy!!
Stew
samw...@my-deja.com
"Brian Murphy" <bm...@tcon.net> wrote:
> The truly ironic point of this is that Fred offered these scopes at
$2495
> (as recently as 1998) and didn't have enough takers to make it
viable. What
> has changed since then?
People looked at them and through them
samw...@my-deja.com
lude...@my-deja.com wrote:
> In article <392a77e2$0$1398$2c3e...@news.voyager.net>,
> a...@voyager.net (Allister) wrote:
>
> Hi Allister,
>
> I did cut my Apomax tube for 8", now i am able to use binoviwer
without
> barlow
Markus, know that you're on the way to RTMC, but how did your tube
shortening affect the baffles?
Clive Gibbons
Brian Murphy <bm...@tcon.net> wrote:
>I'll bet Dynascopes, and Astrolas outsold Unitrons 5 to 1 during the late
>sixties and early seventies.
>
>BPM
>
>RAnder3127 <rande...@aol.com> wrote in message
>news:20000523230442...@ng-ch1.aol.com...
>> >> I remember the SCT and large aperture scopes killed them.
>> >> -Rich
And just to give yourself a shock, check out an old Unitron
pricelist. Remember those are 1960's dollars! Yikes!!
There'll never be another "UniZoo", though... :)
--
Clive Gibbons
Technician, McMaster University,
School of Geography and Geology.
Clive Gibbons
Chris1011 <chri...@aol.com> wrote:
>This allows some companies to offer ED Apo
>lenses at a lower price, and since today, a lot of amateurs can't see color
>errors even in basic fast achromats, it sounds like a winning concept.
Good one, Roland. :)
It's amazing how little colour error an observer will see, when viewing
through their own scope!
Sometimes, "love is blind", or at least colour-blind. ;)
Chris1011
"worse" problem than chromatic aberration?>>
No, at least in my opinion.
Years ago, Zeiss made 6"F15AS and 8" F15AS semi-apo lenses, which had reduced
secondary spectrum, but the sphero-chromatism was 3 to 4 times larger than that
of a normal F15 achromat. From a design standpoint they had horrendous amounts,
far more than typical fast apo lenses of today. The lenses performed superbly
on the planets. I had some of my best views ever of Mars and Saturn with one of
the 8" F15 AS lenses.
Roland Christen
ASTRO-PHYSICS
Chris1011
From a design standpoint, how much does removing the outside 12.5mm of
the 155EDF lens set improve the overall image quality, in general?
>>
The lens elements are also thinner, so the lens settles down pretty fast.
Tom, now that you've had it for a while, do you think the lens performs at the
level of a $6000 Japanese 5" doublet fluorite? Do you think the scope should be
priced at the level of that highly regarded scope?
Nah. i just can't do it.
Roland
Astro-Physics
TMBack
>The new TMB Flourostar SD scopes are probably using
>a very close Russian equivalent to Ohara FPL-52.
The SD glass that I use in my Flourostar design is
not equivalent to Ohara FPL-52. It is closer to Ohara
FPL-53 in its low dispersion, high Abbe V value.
Thomas Back
TMB Optical
TMBack
>Tom, now that you've had it for a while, do you think the
>lens performs at the level of a $6000 Japanese 5"
>doublet fluorite?
Better, in fact. Let me count the ways.
>Do you think the scope should be priced at the level of
>that highly regarded scope?
Yes, so I could sell more of my 5" apos. :-)
But honestly, no, because a lot of the people that want your
telescopes the most, can't afford $6000 for a 5" scope.
Not that you couldn't sell all your production for that price,
but there really are people that are pushing it to be able to
purchase one of your fine apos at the current prices, which
are a bargain.
Thomas Back
TMB Optical
TMBack
>From a design standpoint, how much does removing the
>outside 12.5mm of the 155EDF lens set improve the
>overall image quality, in general?
On the computer, the level of spherochromatism is
significantly decreased. Visually, it only shows itself
on low contrast Lunar and planetary features, on nights
of good to superb seeing. I want every last bit of contrast
and definition (regardless of aperture) out of the
telescopes that I own and use.
My goals may not be the same as most observers,
but optical quality is my top priority.
Thomas Back
TMB Optical
Glenmore F. Wong
was poorly designed and the focuser was nowhere near as robust as on a
Tak or AP.
glenmore
RAnder3127 wrote:
>
> This is not meant to sound
> combative, so don't take it as
> such, because the answer you give
> goes to the core of why a person would
> use one very similar scope over another.
> How can you justify keeping both the
> AP130 (apart from it's value as an
> appreciating asset)and the TeleVue 140mm? It would seem the
> TeleVue offers all the positives and is
> compact as well. Under what observing
> conditions would the AP be chosen over
> the TeleVue or vice-versa? I'm thinking the
> AP has some attribute the TeleVue doesn't, but I just don't know what that
> would be. It would be nice to be in that
> position, but from what I can tell, choosing
> a scope to observe with might require
> a coin toss!
Rich N.
samw...@my-deja.com wrote in message <8gggvu$69v$1...@nnrp1.deja.com>...
>In article <silt7p...@corp.supernews.com>,
> "Rich N." <rnapo*remove*@znet.com> wrote:
>>
>> The 180EDT, 155EDT and 130EDT were all made in
>> longer focal ratios than the EDFs. I believe the f/7 and
>> f/6 EDF needed to use FPL 53 to achieve the color correction
>> of the longer fl EDTs using FPL52. Maybe Roland or others
>> can help here. I don't think the performance is less in a
>> 130mm f/8 EDT than a 130mm f/6 EDF.
>>
>> The latest AP 130 f/8.35, I believe, uses FPL53 and should
>> be a little better than the earlier AP 130mm f/8s with FPL52.
>
>Rich, this doesn't change my perspective. If Roland can achieve
>similar correction at a shorter focal length, then the FPL53 is a more
>versatile glass. I believe that FPL52 becomes then inferior to it as
>you can't achieve the EDF level of correction at f/6-7 with FPL52. Yet
>you can design an awesome APO at f/8-9 (EDT) with FPL53. The 130 f/8.3
>is the perfect example. Even Roland has commented that it is a
>production issue to build this scope instead of the 130 f/8 EDT as he
>can use his 155EDF tooling.
Hi Stew,
Now you're changing the argument from the perfomance
of the EDT vs EDF scopes, to the virutes of FPL52 vs FPL53.
My point was the EDTs weren't being made in the shorter
focal ratios and so still have excellent performance.
I'm very happy AP is using FPL53 in the AP 130mm f/8.35.
I AP hope they will produce more of them.
>
>I am sure that there is not a single one of us that wouldn't want
>Thomas Back's 180 EDT. Yet in all the other EDT's I've seen for sale,
>they don't have the price support of the EDF's. The market perceives
>them to be of less value, maybe only because they are a little slower
>and not because they use FPL52.
I think you are right that more people seem to want the faster
telescopes.
I don't care what type of glass is used in a telescope as long
as the telescope has excellent performance.
I have a couple of EDTs and one EDF. I've had a chance to
compare them with other brands and other APs. So, I'm pretty
familiar with EDTs and EDFs. Maybe one of these days I'll
get to have a look through an Apomax.
Rich
>And if we go back to what the original poster wanted out of this
>thread, even you have baised his decision toward the faster of the
>two. All I have been trying to say is that the APOMAX is unbeaten by
>any other scope I own. And to make use of that I have to put up with
>its length and mount restrictions. I can tell you that the 155EDF is a
>whole bunch nicer to throw up on the mount than the APOMAX. Hence my
>agreement with you that the original poster should keep his AP130. My
>brother feels his will probably be his last scope, end of search.
>
>Stew
>
>
RAnder3127
>prefer the color-correction applied to an out-of-focus plane. ~8^)
How were the photographic AP apos in the mid 1980s corrected? I remember they
used to sell them as an option to the
visual scopes.
John J. Kasianowicz
I've read Suiter's book and understand some of the virtues of a star test.
However, I am not convinced that it is the best test of a refractor's
_chromatic aberrations_, which was the point I was originally addressing.
If an APO optic is designed to have a minimum of color aberration at the
"plane" of best focus (which is part of a sensible design for that type of
optic), all colors may not converge at any "plane" other than the plane of
best focus. Mirabile dictu, the color convergence should get worse at any
plane other than the focal plane.
I have not yet had the pleasure of observing through an APOMAX. If I learn
your name, and if we meet at a star party, I'd be delighted to view the
planets through your scope.
BTW, much to the chagrin of my wife, I too am very picky about the optics
that I buy and use. A-P's EDF scopes have never disappointed me. I own one,
will be pleased if I can order another, and have enjoyed views of planets,
the moon and DSOs through other folks' A-P instruments.
I will ask again, has anyone ever detected false color on the planets or a
bright star on a modern A-P EDF APO refractor that is set to best focus?
Let's be reasonable, the object should not have been near the horizon.
<samw...@my-deja.com> wrote:
> I do most of my viewing in focus as well, however all fun aside, there
> are serious evaluations going on all the time between folks that spend
> many thousands on OTA's. Roland, and any other manufacturer out there,
> certainly knows that their scopes will be tested. The smallest
> variations, that can best be detected in the out-of-focus images, are
> large issues to many of us. Issues that mean big bucks to
> manufacturers. There are more than a few on this list that refuse to
> settle for less than the best. Each and every one star tests and makes
> use of those out-of-focus images. They may accept tradeoffs such as
> focal length, or cost (I got to 8" with an achromat at f/12 cause it
> was cheap, yet the optics are made by a hobbyist that put more time
> into them than any manufacturer could or would!), whatever; but I am
> pleased and consider myself lucky that I own an APOMAX. It has the
> best optics I own. It might have been easier to get right because it
> is f/12, but I really don't care about that, the figure is better, the
> color correction is better. It is simply the best! I would put it's
> images against any other 5" at 24X (65mm Leitz 90 deg, 3.7 deg field,
> 5.4mm ep) to 634X (2.5mm Vixen Lanthuim) and feel confident that it
> would come out a winner under the most critical evaluation. Heck, I
> probably feel as good about this scope as Thomas Back feels about his
> 180 EDT!
>
>
Rich N.
John J. Kasianowicz wrote in message <8ghu5l$e9k$1...@bob.news.rcn.net>...
-snip
>>I will ask again, has anyone ever detected false color on the planets or a
>bright star on a modern A-P EDF APO refractor that is set to best focus?
>Let's be reasonable, the object should not have been near the horizon.
Hi John,
I haven't noticed any false color with an AP EDF when set to best
focus. Most of my EDF experience is with the f/7 155mm.
I can see a little atmospheric refraction even when Jupiter is well up
from the horizon.
Rich
John J. Kasianowicz
samw...@my-deja.com
"Rich N." <rnapo*remove*@znet.com> wrote:
> Now you're changing the argument from the perfomance
> of the EDT vs EDF scopes, to the virutes of FPL52 vs FPL53.
> My point was the EDTs weren't being made in the shorter
> focal ratios and so still have excellent performance.
Sorry, thought I yielded on that somewhere else here. I fully accept
that the current EDTs and the design in general offers the same
performance level as the EDFs, although another question for Thomas
might be how the design of the 130 f/8 EDT compares to the design of
the 130 f/8.3 EDF, especially for spherical given that color is zilch
and since Roland is only offering the f/8 EDT at this time.
> I have a couple of EDTs and one EDF. I've had a chance to
> compare them with other brands and other APs. So, I'm pretty
> familiar with EDTs and EDFs. Maybe one of these days I'll
> get to have a look through an Apomax.
Only seen one EDT and it was an older Traveler, and am not sure if it
was FPL53 or FPL52 based, given Roland's comment in this thread about
naming conventions. The star test was simply excellent and it had to
be 4-5 years old? I hope you get to look through one as well (APOMAX
that is). Come to Astrofest and look at Mark's.
Stew
Vahe Sahakian
> telescopes the most, can't afford $6000 for a 5" scope.
> Not that you couldn't sell all your production for that price,
> but there really are people that are pushing it to be able to
> purchase one of your fine apos at the current prices, which
> are a bargain.
You are obviously referring to Takahashi scopes in the above post. If
you think $6000 for a 5" is excessive let us go back ten years when
Takahashi was the Lone Ranger in apo field, Roland was just beginning to
be recognized but he was not considered as a serious threat to the Tak
boys.
I priced two 6" Tak apos back then, the triplet was listed at about
$24,000 and the doublet was listed at about $19,000 as you know they
have come down considerably thanks to competition, primarily from AP.
Anyway that you look at this, AP prices are more than reasonable, both
the 5" and the 6" apos are real bargains for anyone looking for the
best.
Thanks,
Vahe
Vahe Sahakian
> I will ask again, has anyone ever detected false color on the planets or a
> bright star on a modern A-P EDF APO refractor that is set to best focus?
> Let's be reasonable, the object should not have been near the horizon.
Hi John,
Let me elaborate this question, first, I do not have a modern EDF, mine
is an ancient EDT 155mm f/9 circa 1993, I have compared it to one of the
modern f/7's, both performed about the same from false color stand
point.
Now I always considered the EDT pretty much without any false color, in
fact it did pass one of the tougher tests, showing no color on Moons
limb, both horizontal and vertical at about 230x.
When I got the TEC Maksutov things changed a little bit, I compared the
Jupiter in both scopes at around 230xEDT & 275xTEC and started to notice
a ever slight color in the refractor, there indeed was a tiny trace of
bluish tint at one limb and an equal amount of purple on the opposite
side, now mind you we are talking a really small amount, something that
I never noticed in 8 years of use with the refractor.
All modern apos do have a very small amount of color, you will only
detect this false color when you compare the views with an instrument
that has considerably better color correction and that is what happened
to me when I compared the Mak with the refractor.
Thanks,
Vahe
samw...@my-deja.com
test.
> However, I am not convinced that it is the best test of a refractor's
> _chromatic aberrations_, which was the point I was originally
addressing.
One comment and one question.
The star test is a measure of the similarity of the cones of light
ahead of and behind the optimal focus point. The better color
corrected a refractor, the more these cones of light are coincident.
the poorer the correction, the more the focus points of different
colors shift along the axis, as the cones ahead of and behind the
optimal focus point shift. We say that these very fine APOs are nulled
for color at the optimal focus. In reality there is always some error
for any other color than the one that comes to focus at the optimal
focus point. That's why we look at spot diagrams. How much error is
there in the blue or violet. How much error is there with respect to
the Airy disk. Will I be able to see it in the in-focus image. So
even if you cannot see any 'false' color in the in-focus image, I
submit to you that if it shows up in the defocused image, it's also
there in the focused image. We just can't see it. In that way, I can
detect it better with the star test and can say something about the
quality of the color correction of any refractor with the star test.
Also, because of the star test's sensitivity to color, to get the best
indication of spherical correction, we often use narrow band green-
yellow filters to see only the light cone similarities for that color
range most sensitive to our eyes.
My question is: How would you evaluate the color correction of a
refractor if not with the star test?
> I have not yet had the pleasure of observing through an APOMAX. If I
learn
> your name, and if we meet at a star party, I'd be delighted to view
the
> planets through your scope.
Stew Squires and I live in Denver,
> BTW, much to the chagrin of my wife, I too am very picky about the
optics
> that I buy and use. A-P's EDF scopes have never disappointed me.
I have only seen one of Roland's lenses that had a significant zonal
error. It was in a 130 Brandon f/8 that passed through my hands about
2 years ago. The buyer of that scope absolutely loves the images it
gives, as did the previous owner. Please understand that the errors
I'm talking about have little to do with enjoying the scope. The goal
here for many of us to have the telescope and eyepieces become the
least component of the viewing equation. I am confident that any
modern EDF or EDT meets that requirement. When the scope and the
eyepiece(s) are no longer an issue in viewing, you can concentrate on
those fleeting moments of great seeing and observing technique, and
will never have to ask yourself, is this as good as it gets or is my
scope holding me back?
Sorry to be so long winded, and hope this made some sense. I am sure
that there are others here that could explain it a lot better.
John J. Kasianowicz
[snip]
> The star test is a measure of the similarity of the cones of light
> ahead of and behind the optimal focus point. The better color
> corrected a refractor, the more these cones of light are coincident.
> the poorer the correction, the more the focus points of different
> colors shift along the axis, as the cones ahead of and behind the
> optimal focus point shift.
> We say that these very fine APOs are nulled
> for color at the optimal focus. In reality there is always some error
> for any other color than the one that comes to focus at the optimal
> focus point. That's why we look at spot diagrams. How much error is
> there in the blue or violet. How much error is there with respect to
> the Airy disk. Will I be able to see it in the in-focus image.
I agreed that they're _optimized_ for minimum color at optimal focus. A-P's
spot diagrams (at different wavelengths) and graphs of the secondary
spectrum focus variation as a function of wavelength shows that this is
indeed true. A-P's correction for chromatic aberration is excellent, but not
perfect. It must be difficult to simultaneously minimize chromatic
aberration and all other aberrations in a refractor.
>So even if you cannot see any 'false' color in the in-focus image, I
> submit to you that if it shows up in the defocused image, it's also
> there in the focused image.
In practice, that is true. That is why I used the word "minimum color" (or
something to that effect) and aksed whether _anyone_ could actually see it
in modern APOs.
>We just can't see it.
At least in the finest modern APOs.
> In that way, I can
> detect it better with the star test and can say something about the
> quality of the color correction of any refractor with the star test.
> Also, because of the star test's sensitivity to color, to get the best
> indication of spherical correction, we often use narrow band green-
> yellow filters to see only the light cone similarities for that color
> range most sensitive to our eyes.
If an optic shows no discernable spurious color to the eye, and if the
instrument is to be used for visual observing only, I'd then check for the
other aberrations. I've been so very impressed by the striking planet images
in A-P's modern APOs that I really am not concerned with the tiny amount of
residual color, which must exist. If others here are upset about the
neglibile amounts of spurious color in their modern A-P 155mm f/7 APOs, I'll
be happy to take one off their hands.
I don't know if Vahe's interesting observations with an older vintage A-P
APO applies to the more recent A-P varietals. However, I'm sure he still
enjoys observing the planets with his refractor. If not, ...
Based on my views through modern A-P APOs, I'd be very pleased to own and
use a few (I don't invest in instruments for their potential to appreciate
in value, I only want them for the pleasure they can bring at the EP). The
only APO I have is a Traveler (great travel scope). I hope that w/in a few
years I can buy an A-P 155 mm f/7 OTA. I will also be pleased to look at
Thomas Back's larger APOs (one really can't have too many fine scopes,
true?). Mind you, I may have to enlarge my observatory to accomodate
additional scopes (and a cot to sleep on, should my wife get justifiably and
overly upset with me).
> My question is: How would you evaluate the color correction of a
> refractor if not with the star test?
That is a good question. I don't know of an easy and cheap method.
Personally, I'm happy to use my eye with the scope at optimum focus. That
crude test does not tell me how steeply the differently colored light cones
converge towards the plane of optimum focus, but it lets me know if the
optic is worthy of consideration.
I've looked through an older A-P 6" f/12 scope. It's a very nice instrument,
but the one I peered through at had too much spurious color for my taste.
Although I don't like extrapolating based on one observation, I am not
surprised that Roland designed a more modern apochromatic triplet.
Sue and Allan French have a lovely vintage large A-P optic (I think it's an
8" diameter refractor with f/long). I don't know how well the scope is color
corrected, but the tack sharp images of the moon and planets are compelling.
I'd be happy to take this scope off their hands, but I don't know where I'd
put it. I suppose my wife would have some pointed suggestions on the latter.
~8^0
> > I too am very picky about the optics
> > that I buy and use. A-P's EDF scopes have never disappointed me.
>
> I have only seen one of Roland's lenses that had a significant zonal
> error. It was in a 130 Brandon f/8 that passed through my hands about
> 2 years ago. The buyer of that scope absolutely loves the images it
> gives, as did the previous owner. Please understand that the errors
> I'm talking about have little to do with enjoying the scope. The goal
> here for many of us to have the telescope and eyepieces become the
> least component of the viewing equation. I am confident that any
> modern EDF or EDT meets that requirement. When the scope and the
> eyepiece(s) are no longer an issue in viewing, you can concentrate on
> those fleeting moments of great seeing and observing technique, and
> will never have to ask yourself, is this as good as it gets or is my
> scope holding me back?
I completely agree with your desire for wanting the best optics that you can
afford. This lust for quality glass is even more critical when one realizes
just how little observing time we have on this planet and that our eyes
generally get worse with increasing age (for some of us, progressive eye
diseases make the time factor even more acute).
Chris1011
even if you cannot see any 'false' color in the in-focus image, I
submit to you that if it shows up in the defocused image, it's also
detect it better with the star test and can say something about the
quality of the color correction of any refractor with the star test.>>
Color correction is a very complex thing, and there are many ways a designer
can skew the design to make color more or less perceptible.
You are right, of course, that there will always be a bit of color error due to
sphero-chromatism, etc. in apo refractors. The very fact that the colors in an
Apo come so very close to focus (and are not spread out into a thin
imperceptible haze), allows you to see them as slight fringes on the out of
focus patterns. It is ironic then, that when a lens has very poor color
correction, you may not see or notice a lot more of this when defocusing the
image. For instance, if the blue end of the spectrum goes out of focus ever so
slowly with decreasing wavelength, there is a lot of energy in the slightly out
of focus waves. If, on the other hand, the blue end goes out of focus very
rapidly, the decreasing wavelengths are so far out of focus, that the energy is
spread out very far away from the disc, and contributes very little to the
fringing effect. Thus, an inexperienced tester could easily conclude that a
lens with very poor color correction in the blue does not seem to have very
much color error. The color error is indeed there, but being so far spread out,
it seems to disappear into "thin air".
In lenses, the key is the color of the in-focus disc. The whiter it appears at
focus, the better is the correction. In a lens with lesser color correction,
the in-focus disc will appear more and more yellowish (at reasonably high
powers of course). The resolution is not necessarily any different, but the
main effect is that with better color correction, there is more light
concentrated in the image, and fainter stars can be seen. Globulars, for
instance, should look more crisp and the individual stars in the globular
should have more of that sugar sparkle look.
One can indeed make a fast achromat that would appear to have "very little
color", simply by bringing the red end of the spectrum closer to the yellow and
green waves. This sacrifices the blue end. In other words, if you cut the red
error in half in a normal achromat, the blue error will double. This is called
Cde correction (red yel green) as opposed to the normal CeF (red green blue)
correction. The old time achromat designers tried to include as much of the
visible waves as possible with the CeF correction, and relying on long focal
lengths to increase the depth of focus and reduce the perceived color error. If
a 6" F8 were made that way, it would look colorful, indeed. By skewing the
color curve toward the red, and sacrificing the blue end, the perceived fringe
does not look any bigger (far out of focus blue and violet waves have very
little energy per unit area). Since the red end is close to focus, you will not
see the typical "purple fringe", which is not really violet light, but the
combination of red and blue.
At low power, these lenses do have an almost Apo look to them, especially on
the Moon. With an object that bright, two things happen. Your eye's color
perception shifts over to the red end of the spectrum, and because of the
brightness entering your eye, your pupil contracts. In effect, your eye stops
down the aperture. So, instead of seeing the Moon with a 6"f8, you may be
stopping it down to 3 or 4 inches due to pupil contraction. If you move your
eye around the eyepiece, you may catch glimpses of the light originating from
the outer part of the lens' aperture, and will see various amounts of violet
and blue flaring in and out. On deep sky, the eye has no color response, and
everything looks white, no matter how well or poor the color correction is. I
would expect a 6" F8 achromat with Cde correction to show bright globular star
clusters buried in a thin nebulous haze (the out of focus blue and violet
light). The brightness of the haze would be less, the worse the color is, and
would depend, of course, on the magnitude of the cluster. If this background
haze is below the detection limit of the eye, you might not see any. It would
be interesting to compare this nebular background in CCD images taken with this
kind of lens vs a mirror scope, or high end Apo.
Roland Christen
ASTRO-PHYSICS
Rich N.
Vahe Sahakian wrote in message <392CA131...@flash.net>...
Hi Vahe,
When you see blue on one side and a warmer
color on the other side of a planet, isn't this more
likely a result of atmospheric refraction?
Rich
ar...@selena.kherson.ua
chri...@aol.com (Chris1011) wrote:
> One can indeed make a fast achromat that would appear to
> have "very little color", simply by bringing the red end of the
> spectrum closer to the yellow and green waves. This sacrifices
> the blue end. In other words, if you cut the red error in half in a
> normal achromat, the blue error will double. This is called
> Cde correction (red yel green) as opposed to the normal CeF (red >green blue) correction. The old time achromat designers tried to >include as much of the visible waves as possible with the CeF >correction, and relying on long focal lengths to increase the depth
> of focus and reduce the perceived color error. If a 6" F8 were made >that way, it would look colorful, indeed. By skewing the color curve >toward the red, and sacrificing the blue end, the perceived fringe
>does not look any bigger (far out of focus blue and violet waves
> have very little energy per unit area). Since the red end is close to >focus, you will not see the typical "purple fringe", which is not really >violet light, but the combination of red and blue.
>
According to our results of inverse engineering of a Bresser's
objectives 120mm F/1000 and 100mm F/1000 they has
color correction differed from CeF and more likely has Cde
correction. This is a reason why many guys reports that they
"can't" see a color errors. Such Cde correction combined with
fast blue dropping makes these objectives looks "semi-apo"
which is not true at all.
Valery Deryuzhin.
ARIES.
samw...@my-deja.com
Apo.
>
> Roland Christen
> ASTRO-PHYSICS
Thanks Roland, I think that to many there is little to do in designing
optics. One only has to bring up a demo copy of Zemax sometime and
quickly get blown away by the immense number of variables you have to
play with. I appreciate the discourse. None of this is ever simple or
easy to do. (And although you say it's easy to make an f/12 triplet
come out right, guys like me, that would happily pay others to push
glass, simply shudder at the thought of the patience and painstaking
effort really required for the optics in our high-end APOs). I, again,
appreaciate all the work you put into my EDFs, and I appreciate your
commentary here as well.
Stew
Chris1011
objectives 120mm F/1000 and 100mm F/1000 they has
color correction differed from CeF and more likely has Cde
correction. >>
To clarify the situation on color correction a bit more for those who'se
eyelids have not already closed and are nodding away from all this technical
mumbo-jumbo, I will attempt to explain where achros, EDs, fluorites etc fit
into the scheme of things by comparing the ability of each design to produce a
reasonably focused image spot diameter over its wavelength range. Reasonably
focused being somewhere around 25 microns.
Fast 6"F8 Cde achromat: 550 - 650 nm
Long 6"F15 CeF achomat: 480 -650 nm
Fast 6"F9 ED doublet: 450 - 650 nm
Fast 6" fluorite doublet: 420 - 1000 nm
Fast 6" FPL52/53 triplet: 380 - 1000 nm
Fast 6" fluorite triplet: 360 - 1000nm
It would be interesting then to divide the cost of each lens by its useful
wavelength range. For instance, a 6"F8 Cde achromat selling for around $800
today would come in at $10 per nanometer. (our 6" EDFS at $4900 comes in at
$7.90 per nanometer).
Interestingly, an 8" SCT selling for around $900 comes in at $3.81 per
nanometer. No fair asking how a Newtonian would fare!
Seriously, why would you need correction well into the blue-violet past 480nm?
With black and white emulsions, this was necessary because they have
considerable sensitivity down to 380nm. Today's new blue sensitive CCD cameras
also need good correction in the violet. Also, CCD cameras pick up lots of IR
light below 650nm, so correction to 1000nm is a distinct advantage. For pure
visual use, it would be quite sufficient if the useable range extended only
from 440 to 650 nm. So, check the above table for your particular needs and
make your choice.
Roland Christen
ASTRO-PHYSICS
RAnder3127
>was poorly designed and the focuser was nowhere near as robust as on a
>Tak or AP.
140 Story;
A few lucky(?) people who bought
the first 101's might have noticed the large size of the case that came with
it. That's because they had been meant for the
140's that were never produced.
RAnder3127
>would expect a 6" F8 achromat with Cde correction to show bright globular
>star
>clusters buried in a thin nebulous haze (the out of focus blue and violet
>light). The brightness of the haze would be less, the worse the color is, and
That haze is quite noticeable on stars of
3rd magnitude.
Vahe Sahakian
> color on the other side of a planet, isn't this more
> likely a result of atmospheric refraction?
Hi Rich,
The amount of color that is visible on opposite limbs of Jupiter in my
old and outdated EDT is in fact so small that most critical observers
simply can not see it, I am talking splitting hairs here, as I mentioned
before the EDT color error is in-line with the more recent f/7 EDF's and
I have compared them side by side on number of occasions.
As for atmospheric refraction being the cause, yes, it is possible if
the planet is fairly low, but in my backyard where I do most of my
observing Jupiter must be at least 70 degree above horizon before it
clears the trees.
When Jupiter returns you can try your old and outdated 180 EDT, and if
you really concentrate and look for it you will see it, it is there.
The atmospheric refraction was my prime suspect for this barely
detectable coloring at the planet limbs, that theory was dismissed
because no color was detectable in the Maksutov, none at all and at any
power, so there you have it.
As for the "old" refractor, perhaps I am a little too picky, the color
correction in this old thing is simply superb, I just feel that any apo
will show a tiny amount of color, that is, if you know where and how to
look for it.
If you want true and honest zero color error system, stay with
Newtonian.
Thanks,
Vahe
ericj
> Yes, I did say that, but it was before I received my
>1/22 wave P-V Astro-Physics 5.1" f/8.35 EDT (F) apo.
>The lens is awesome, and I'm sure it performs at the
>"APOMAX" level.
Hi Thomas:
Agreed. I have been very impressed with the 5.1" f/8.35 EDT (F) as well.
Some of the best views I had of Jupiter and Saturn last year were with this
scope, and it has done a fine job on deep-sky objects as well.
Clear Skies,
Eric
Rich N.
Vahe Sahakian wrote in message <392DB11E...@flash.net>...
>> When you see blue on one side and a warmer
>> color on the other side of a planet, isn't this more
>> likely a result of atmospheric refraction?
>
>Hi Rich,
>
>The amount of color that is visible on opposite limbs of Jupiter in my
>old and outdated EDT is in fact so small that most critical observers
>simply can not see it, I am talking splitting hairs here, as I mentioned
>before the EDT color error is in-line with the more recent f/7 EDF's and
>I have compared them side by side on number of occasions.
>As for atmospheric refraction being the cause, yes, it is possible if
>the planet is fairly low, but in my backyard where I do most of my
>observing Jupiter must be at least 70 degree above horizon before it
>clears the trees.
>When Jupiter returns you can try your old and outdated 180 EDT, and if
>you really concentrate and look for it you will see it, it is there.
>The atmospheric refraction was my prime suspect for this barely
>detectable coloring at the planet limbs, that theory was dismissed
>because no color was detectable in the Maksutov, none at all and at any
>power, so there you have it.
Hi Vahe,
You may be right. Maybe one of the optics experts can help.
I would think if the color was due to the lens, the color would
be even around the planet. Maybe that obstructed Mak just
can't pick up the colors like your old and outdated refractor? ;-)
I still like my "old and outdated" 180EDT.
Rich
Buddy In NY
No ones nodding out :). this is great stuff!
The original poster(me) asked "whadda ya think", Well I got what you all
think ,plus a lesson in optics. I know more now than I did a week ago
thanks goes out to you & the others for taking me to school
--
~ Buddy In N.Y.~
~Urban Guerrila Astronomy~
Chris1011 <chri...@aol.com> wrote in message
John J. Kasianowicz
triplet?
Mark
Stew, I didn't mean to appear to be trouncing on you. I do know that
you are the largest fan of the Apomax scope, (Even more so than I).
You are correct to state that FPL-52 would be inferior to FPL-53 ED.
All in all, IMO, Fred has done a fine job with his first production
scope, The Apomax.
The mechanics/aesthetics of the Apomax truly say to me "A Classic"
When I had first seen the mechanicals/individual components of this
scope at Astrofest '96, I was very impressed.
Fred recently has made larger Apo refractors on a custom order basis,
and now uses the more costlier Ohara FPL-53 ED. All the scopes he has
produced so far have been an extremely good value, and would go as far
to say "Are a Steal"
I myself, and surely many others hope that Fred continues his pursuit of
Telesope manufacture, and perfection.
Also Tom B., Thank you for the clarification/correction about the SD
lens used in you Flourostar refractors, and I also wish you good luck in
your pursuits.
Mark
ToddG18522
intelligence on this one, Dave.
The longer you let your tubes cool down, the smarter you'll feel <g>.
Roland.. Can I post this email on my
weatherman.com web page, it was informative yet simple enough for a dummy like
me to understand ??
David M. Lent
a...@voyager.net (Allister) wrote:
> Hi Buddy,
>
> If you have the chance to buy an Apomax, buy it! There are only
> snip....
> I didn't star test the scope as I'm simply not experienced enough to
I hate to start trouble... but how can you tell people to buy a certain
scope if you haven't star tested it yet? This is an expensive scope.
Be more responsible before telling people to buy it!
--
David M. Lent,
http://www.astrosights.com
The Amateur Astronomy Web Directory, Forums and Classifieds.
RAnder3127
>triplet?
Or "wedge" in one or more elements?
Mark
Of the Apomax scopes I have viewed through, (4) all have exhibited the
same fine optics.
Fred's critical care, and testing had pretty much guaranteed killer
optics on all samples, with very little, to no variation in P-V/RMS
values. Mark
Allister
You are correct on two counts. I did recommend a scope to someone I
didn't know (mistake #1) prior to putting it through a reasonable
amount of testing (mistake #2). As of late I've been spending greater
amounts of time on private astro chat groups where I can be "bubbly
and enthusiastic hobbyist Allister" and the folks there understand. I
had a momentary lapse and should have thought through my intended
message prior to posting it here on SAA.
Thanks
Allister
a...@ais.net
Rich N.
David M. Lent wrote in message <8gnehm$7uv$1...@nnrp1.deja.com>...
>In article <39292a61$0$1408$2c3e...@news.voyager.net>,
> a...@voyager.net (Allister) wrote:
>> Hi Buddy,
>>
>> If you have the chance to buy an Apomax, buy it! There are only
>> snip....
>> I didn't star test the scope as I'm simply not experienced enough to
>
>I hate to start trouble... but how can you tell people to buy a certain
>scope if you haven't star tested it yet? This is an expensive scope.
>Be more responsible before telling people to buy it!
>
>--
>David M. Lent,
>http://www.astrosights.com
Hi David,
You could still see that a telescope was performing
well and recommend it with star testing it. If an Apomax
and a scope of known fine quality were compared side
by side, looking at say Jupiter, you could get a good idea
if the Apomax was worth recommending.
I wonder how many people really can judge a start test
accurately? I've read Suiter's book and star tested quite
a few scopes but I don't think good enough to recommend
a scope just on its star test.
Rich
Buddy In NY
I would never buy a scope wih out a good testing of the optics &
mechanics(espesially if i were to swap my AP for it). If get an
enthusiastic responce from,,,say,,, Allister,,, who after reading his
reviews of the scope & his website in general,, tend to lead me to belive
this scope is "most Likley Good",, Also I might add that its not a
commercial SCT were taking about here,, its a legendary scope. Altho
Allister is more experianced than I,, there is no one on Saa who has Dr.
Svengalli, like influance, on my self. One thing I do know fron Allisters
responce is that he ,,indeed,, is impressed with his ApoMax. I asked for
folks"wadda ya Think",,Alilister told me what he thought
Clear skys to all
~ Buddy In N.Y.~
~Urban Guerrila Astronomy~
> I hate to start trouble... but how can you tell people to buy a certain
> scope if you haven't star tested it yet? This is an expensive scope.
> Be more responsible before telling people to buy it!
>
> --
> David M. Lent,
> http://www.astrosights.com
Mark
"new scope" before you buy it. Not AP, Not Tak, nor Meade, or Celestron
or anyone else.
This is what the warrantee is for. (Unless you buy one at a Star-Party)
With companies such as AP, or HTPO (Apomax), it means something. It
means they will bend over backwards to see that your satisfied, or
refund your money in full. (I believe it's 30 days with AP, and was 60
with HTPO)
Not that either company wouldn't stand behind it beyond this time
period, they will, if a manufacturing defect was found to be the
cause/fault.
With companies such as Meade, and Celestron , Well, lots of luck!
In this senario, it would most likely be the integrity of the dealer to
either exchange merchandise, or refund your money.
It seems the only way us amateurs have is either by the advice of
freinds/other experienced amateurs, or first hand use of such
instruments.
The little ads that AP puts in the back of every Sky, and Tele surely
cost gobs of $$$.
This is not what sells their scopes though, it is word of mouth, and
their fine reputation that does. Don't you agree? Mark
David M. Lent
No problem. I shouldn't have jumped on you like that.
ar...@selena.kherson.ua
"Rich N." <rnapo*remove*@znet.com> wrote:
> I wonder how many people really can judge a start test
> accurately? I've read Suiter's book and star tested quite
> a few scopes but I don't think good enough to recommend
> a scope just on its star test.
>
> Rich
>
Very resonable point of view on a star test, Rich.
Valery Deryuzhin
ARIES.
Buddy In NY
he wanted to swap my Ap130 for his Apomax ,, I was going to meet him & test
the scope under dark skies in Penn,, In this situation i could test it.
> Hi Buddy, Not trying to be critical here, but no one will let you try a
> "new scope" before you buy it. Not AP, Not Tak, nor Meade, or Celestron
> or anyone else.
I never got warrente card on a used scope <G> Id rather drive 200 miles to
test it than go through the hassel of retuning it. .As for AP,, TMB,TV,
Aries & a few others that I forget at the moment,, faith in their
integrity(& warrente) goes a long way ,,so I agree with you there. Ive owned
A C8 it sucked. I owned a Meade It was mediocre. for me to buy from "C" or
"M" agaian the dealer would have to let me in at night & check the scope
aint likley to happen).
but when you put over a $1000 down on a scope,, they should accomidate you.
i never bought a used car that i couldnt drive first
clears skys to you
--
~ Buddy In N.Y.~
~Urban Guerrila Astronomy~
Mark <MarkDa...@webtv.net> wrote in message
news:9611-393...@storefull-227.iap.bryant.webtv.net...
Dave Novoselsky
near the record at all) it occurs to me that the guy with the Apomax may
have simply been trying to trade a shorter, easier to manage 5" for his
otherwise excellent but admittedly long and difficult to mount scope.
Buddy, if the guy still wants to unload his Apomax (but I am not interested
in a trade) have him contact me. Dave
"Buddy In NY" <maxwe...@mindspring.com> wrote in message
news:8gr2k3$hm9$1...@slb0.atl.mindspring.net...
Rich N.
ar...@selena.kherson.ua wrote in message <8gqfdh$69l$1...@nnrp1.deja.com>...
>In article <sj074lk...@corp.supernews.com>,
> "Rich N." <rnapo*remove*@znet.com> wrote:
>
>> I wonder how many people really can judge a start test
>> accurately? I've read Suiter's book and star tested quite
>> a few scopes but I don't think good enough to recommend
>> a scope just on its star test.
>>
>> Rich
>>
>
>
>Very resonable point of view on a star test, Rich.
>
>
>Valery Deryuzhin
>ARIES.
Thank you sir.
Rich
ToddG18522
>>But which AP 5" The AP 130 f/6 is an incredible scope. But the latest AP
130 f/8.3s are a tick better.<<
Hi Dave!
Dave.. I think you should note that your above statement is only a
generalization based on a good "data-point" that you have come across + common
sense.
tg
ar...@selena.kherson.ua
"Rich N." <rnapo*remove*@znet.com> wrote:
>
> ar...@selena.kherson.ua wrote in message <8gqfdh$69l$1...@nnrp1.deja.com>...
> >In article <sj074lk...@corp.supernews.com>,
> > "Rich N." <rnapo*remove*@znet.com> wrote:
> >
> >> I wonder how many people really can judge a start test
> >> accurately? I've read Suiter's book and star tested quite
> >> a few scopes but I don't think good enough to recommend
> >> a scope just on its star test.
> >>
> >> Rich
> >>
> >
> >
> >Very resonable point of view on a star test, Rich.
> >
> >
> >Valery Deryuzhin
> >ARIES.
>
> Thank you sir.
>
> Rich
You are welcome. :-)
Valery.
samw...@my-deja.com
"Rich N." <rnapo*remove*@znet.com> wrote:
> I wonder how many people really can judge a start test
> accurately? I've read Suiter's book and star tested quite
> a few scopes but I don't think good enough to recommend
> a scope just on its star test.
Hi Rich,
I wonder sometimes too, yet star testers seem to fall into two
different groups. The fanatics, that would almost rather star test a
scope than observe, and those that do a quick in and out on a settled
scope and move on. I think that with experience you can see subtle
detail that others would miss. Without lots of experience with lots of
scopes (and many different designs as well) you have only a small
chance to get all the information possible. And, short of
interferometry, there is really no alternative to check out a scope
short of using fine or low contrast planetary detail. And this is
always subject to seeing. Testing on stars is also subject to seeing,
but you're always able to tell when seeing makes the test worthless.
Comparisons, such as you did with Jay recently on lunar details are
really the best way to compare optics in two different telescopes. We
all knew how these two faired after your and Jay's (mostly Jay's)
excellent report.
Stew
SHAPERINO
My grandparents came from a town in Ukraine called, I believe, Novoselits or
Novaselits (I never saw it written, only heard it pronounced). Is there any
connection with that town for you?
Larry Shaper