Borg refractors vs. Tele Vue
Deane Clark
There's plenty of choice in 4" size scopes, but this doesn't seem to be a large enough
jump in aperture to make it worth another $2.2K for the TV-102 (for example).
I've recently realized what a good deal the Borg 125ED seems to be relative to other 5
inchers out there.
Does anyone have any experience with this scope, and maybe specifically how it compares to
the TV or Tak 4 inchers? Are the Borg EDs as color corrected as a TV-85?
If you have one of these, how do you like the helical focusser?
What added cost accessories do you feel are required, assuming use with a 2 inch star
diagonal?
Finally, how quickly can a person get one? I hope the line isn't AP-like.
TIA,
Deane Clark
clark...@qwest.net
Ron B[ee]
Yeah, going to a 4" isn't much of an upgrade.
I've just made a stunning discovery. Check this out; I don't know who
actually make this Burgress scope though. Does anyone know?
http://www.handsonoptics.com/astronomy/burgess/burgess.html
Vixen also makes a 114mm ED refractor at a lower cost than the Borg. Or the
Meade 127mm ED (if you want to take some chances).
This may be heresy (since I own a TV-102 ;-), but have you considered other
types of larger scope (MCT, MNT or Newtonian)? It would nicely complement
your TV-85.
Good luck,
Ron B[ee]
--------------
"Deane Clark" <s...@below.com> wrote in message
news:3B26F722...@below.com...
Deane Clark
Yeah, I've been looking at the vixen 114 too, and would also be interested in info from
those who have looked through one.
Newtonians still scare me due to the collimation. I've got an old late '70s Edmund 6 inch
that's a bitch to adjust the secondary on.
I actually do have a 6 inch Mak (Argonaut/MK67) but the cooldown time is murder in the
cold months. If anyone has come up with a fan attachment for it, I'd be very interested.
May you not have the weather we're having,
Deane
--
Deane Clark
clark...@qwest.net
Ron B[ee]
both the Newtonian and the MCT!
The 114ED is so new and I haven't seen any review yet. But here's
some info which may be helpful.
http://www.observers.org/tac.mailing.list/1999/December/0561.html
http://groups.yahoo.com/group/Refractors/message/3504
http://www.observers.org/reports/2000.11.02.2.html
http://www.observers.org/reports/2000.11.18.2.html
http://www.observers.org/reports/2000.09.23.html
http://www.observers.org/reports/2000.09.20.3.html
Good luck,
Ron B[ee]
--------------
"Deane Clark" <s...@below.com> wrote in message
news:3B270F64...@below.com...
Siegfried Gonzi
Deane Clark schrieb:
> I'm a TV-85 owner who is very happy, but getting a craving for a larger refractor.
> There's plenty of choice in 4" size scopes, but this doesn't seem to be a large enough
> jump in aperture to make it worth another $2.2K for the TV-102 (for example).
>
> I've recently realized what a good deal the Borg 125ED seems to be relative to other 5
> inchers out there.
Buy a 6inch Maksutov from Intes or Orion and you get:
a) concerning contrast: *at least* a 4inch apochromatic refractor maybe a 11.5cm apochromatic
refractor
b) the about light-grasp of a 5inch refractor (here there are included the loss due to mirror
reflectivity)
c) the 15cm Maksutov is only 4kg and it is short that means you can use a weak mount (have you
ever seen such a big thing like a 5inch refractor; though the Borg ones are not that clumsy)
c) and this all for about $1000 (the mount is not included here)
>
>
> Does anyone have any experience with this scope, and maybe specifically how it compares to
> the TV or Tak 4 inchers? Are the Borg EDs as color corrected as a TV-85?
The Borg ED is as good as color-free:
http://www.cloudynights.com/reviews.htm
(and therein you will find Borg ED testreports)
> If you have one of these, how do you like the helical focusser?
People are very pleased with it.
> What added cost accessories do you feel are required, assuming use with a 2 inch star
> diagonal?
> Finally, how quickly can a person get one? I hope the line isn't AP-like.
Look for a Maksutov. There is a refractor-hype and nobody can explain why.
If you can live with Meade you can maybe look for a 7inch Maksutov from Meade.
S. Gonzi
[Notice: The weatherman reports on his testreports site that he was not able to see color in
the Orion-nebula with the MK 65 (Intes Maksutov) though he states that he is able to see color
with a 8inch Schmidt-Cassegrain or 5inch Takahashi. But be aware that are "mini"-testreports
and not very evaluated:
http://www.weatherman.com/
]
Tony Flanders
> Newtonians still scare me due to the collimation. I've got an old
> late '70s Edmund 6 inch that's a bitch to adjust the secondary on.
You really ought to try to get over that. As long as you keep to
refractors, you will be stuck down in the peewee league as far as
aperture is concerned. And once you master collimation, it will
never scare you again. A laser collimator and a few lessons from
a master will cost you a lot less than a 5" refractor!
Adjusting the secondary can be a bit of a pain, but in general,
it only has to be done once, or maybe once a year or so. With
a properly built Newt, collimating the primary just isn't all
that hard once you have the hang of it.
Granted, Newtonians do have other problems. But you shouldn't
let fear get in your way.
- Tony Flanders
Deane Clark
Thanks for the Borg info! I saw the cloudynights reviews. I was hoping to maybe find
someone who has the 125ED.
>Look for a Maksutov. There is a refractor-hype and nobody can explain why.
Got a 150mm Mak. A big reason for my refractor fetish is cooldown time. The Mak takes 1
or 2 hours when it's cold, and this usually keeps me from using it. At least with my
TV-85, cooldown is < 30 min with temps in the 20s F.
>If you can live with Meade you can maybe look for a 7inch Maksutov from Meade.
I'm also a perfectionist, so I am really turned off by Meade's usual sacrifice of quality
for low price/high sales. (Not trying to start a war here - I understand the optics are
usually very good, but why not the whole scope?)
--
Deane Clark
clark...@qwest.net
Deane Clark
This is a heck of a start on the 114 research.
If it's been available since last Sept., there ought to be a few more out there. Any of
you 114 owners out there want to tell us how you like it?
Deane
"Ron B[ee]" wrote:
>
> Wow, you hit the nail on the heads regarding the disadvantages of
> both the Newtonian and the MCT!
>
> The 114ED is so new and I haven't seen any review yet. But here's
> some info which may be helpful.
> http://www.observers.org/tac.mailing.list/1999/December/0561.html
> http://groups.yahoo.com/group/Refractors/message/3504
> http://www.observers.org/reports/2000.11.02.2.html
> http://www.observers.org/reports/2000.11.18.2.html
> http://www.observers.org/reports/2000.09.23.html
> http://www.observers.org/reports/2000.09.20.3.html
>
> Good luck,
> Ron B[ee]
--
Deane Clark
clark...@qwest.net
Johnny
color on the moon up to 163x which isthe highest i've been. I can barely
detect a hint of blue/red on mars at 250x which i shouldnt be at to begin
with. I dont see any color on any stars at high power but i notice that at
around 163-250x, the first defraction ring is not the color of the star
itself. white star has blueish ring. But i dont ever notice the color when
i'm not looking at it and this is my first refractor. i've always owned
reflectors with absolutly no color so you see what i'm comparing to. Even
this small scope takes magnification pretty well i think. last night i had
to use my diagonal between my barlow and eyepiece to tripple the mag to
about 250x to split the double star in Bootes, the one just north of
arcturus. It looked like a hydrogen atom or somethign with a definite dot,
a ring, then another tiney little dot that was right on the ring of the
larger one. pretty cool.
"Siegfried Gonzi" <siegfri...@kfunigraz.ac.at> wrote in message
news:3B27158B...@kfunigraz.ac.at...
Ron B[ee]
> Siegfried,
>
> Thanks for the Borg info! I saw the cloudynights reviews. I was hoping
to maybe find
> someone who has the 125ED.
Dave Novoselsky has one (and several other Borg as well). Join the
Refractors eGroup
http://groups.yahoo.com/group/Refractors/message/3580
Look at message 3580 and its thread (and 3582).
Ron B[ee]
Mark
> Newtonians still scare me due to the collimation.
> I've got an old late '70s Edmund 6 inch that's a
> bitch to adjust the secondary on. I actually do
> have a 6 inch Mak (Argonaut/MK67) but the cooldown
> time is murder in the cold months. If anyone has
> come up with a fan attachment for it, I'd be very
> interested.
You've touched on the two most serious
problems with Newtonian reflectors. Fortunately,
both have straight-forward solutions. The increase
in aperture for your dollar seems worth it to me.
You might disagree though.
I have a home-built 10" F5 truss-tube Dob.
My first collimation (ever) took me about twenty
minutes. A week later, I can both set up the scope
and collimate it in under five minutes. This is
largely due to the fact that once collimated a
little tweaking is all that is necessary, and
tweaking collimation is pretty simple.
I also built a laser-collimator device out
of a laser pointer and some aluminum tubing for
about $10 USD. This makes collimation so simple
that a monkey could do it. It honestly only took
me half-an-hour (plus the time to find the parts)
to throw together. If I can do it, anybody can.
The cooling problem can be solved with a
fan. I've seen fans precariously attached to the
mirror cell with rubber bands. What's more, they
actually worked!
The problems with Newtonian reflectors are,
in my honest opinion, horribly exaggerated. That's
not to say that they are the end-all be-all. (I'd
hate to do a 15 minute guided exposure on my scope.)
However, for visual astronomy they are an amazing
value.
> May you not have the weather we're having,
Unfortunately, I think I am.
Mark
Jeff Medkeff
>Newtonians still scare me due to
>the collimation.
I drive a 2000 Camry and find collimating the mirrors on it
about as hard as collimating any of my Newtonians (which
include an f/4.5 model).
Please tell me you aren't driving around in southern
Arizona. ;-)
--
Jeff Medkeff
Sierra Vista, Arizona
John Bevan
wrote:
> I'm a TV-85 owner who is very happy, but getting a craving for a larger
> refractor.
Deane, I know that if you want a refractor, then you'll probably get
one. But I had something the same problem as you after having had only
small refractors and a Mak all my life and wanting something larger.
I had actually gone down to a TV 85 for travel and have been exceedingly
happy with that choice. After a lot of thought, I ordered a Portaball 8
from Mag 1 Instruments and have been equally happy with this choice.
The increase in aperture (85->200) gives a really worthwhile gain of 1.9
magnitudes (whereas a 5" will net you an extra 0.8 mag). The Zambuto
mirror is superb and, while able to split 0.8" doubles, the real benefit
shows when viewing globulars where the definition truly rivals IMHO
refractors of similar aperture.
The truss design can be assembled or disassembled in a minute or two.
More importantly, the laser invariably shows that the collimation only
needs to be tweaked. The primary's adjustment knobs are conveniently
situated above the mirror.
While obviously not carry on luggage, the Portaball 8 is very compact
and relatively light for surface transport. It weighs about 32 lb,
(whereas the Portaball 10" weighs over 40 - a major point for me)
I got the full electrical package which includes fan and anti-dew
heating for the secondary. The mirror is ready within 20 minutes and
I've never had a dewing problem (unlike my unheated TV 85). I also have
a compact equatorial platform with custom mounts for the Portaball
sphere.
One last thing: there's no scope I know of that is as easy to use at the
zenith.
--
John
remove spam, change refuse to fuse
ccwoodruff
I have the Borg 100ED, I tried the Borg 100 Achro and after my buddy and I
took my ED out he went and bought a Borg 125ED. Comparing my 100ED to
the TV85 & TV101 the Borg weighs the same as the TV85. It is also the same
size as the TV85. The TV's are very slightly sharper. Splitting doubles
are virtually
the same and contrast is basically the same. The TV's are 3% better
optically, if
I didn't have them side by side I don;t think I would know the difference.
The
same was true with the Borg125ED. Basically no color in focus, nice and
sharp.
The cool thing about these scopes is that they are LIGHT but not under
built.
They also unscrew into 2 pieces so they can fit in nice small cases. My
Borg 100ED
lives in a 17x14x6 case. The helical focuser is something to get used to.
It is
not as nice as the TV focusers but they do work nicely. If you are looking
for
the most porable refractors in the 100 to 125 mm sizes with very nice optics
you
can't go wrong with the Borgs. Availability is probably a couple days at
most.
Hope this helps!
Chris Woodruff
www.ccwoodruff.com
"Deane Clark" <s...@below.com> wrote in message
news:3B26F722...@below.com...
Ron B[ee]
Have you had a chance to do a side-by-side comparison between the
100ED or TV101 with your buddy's 125ED? If so, can you tell us about
it? I'm curious to know if the difference is striking.
Thanks,
Ron B[ee]
--------------
"ccwoodruff" <ccwoo...@email.msn.com> wrote in message
news:eZ$3F9P9AHA.256@cpmsnbbsa09...
> Hello,
> I have the Borg 100ED, I tried the Borg 100 Achro and after my buddy and I
> took my ED out he went and bought a Borg 125ED. Comparing my 100ED to
> the TV85 & TV101 the Borg weighs the same as the TV85. It is also the
same
> size as the TV85. The TV's are very slightly sharper. Splitting doubles
...snip...
> Chris Woodruff
> www.ccwoodruff.com
Gary Irwin
Deane:
Like you I love my TV-85 but found I was quickly lusting for more aperture.
I initially bought a 6" Mak-Newt thinking it was a cheap and easy way to get
"big aperture" performance. "Quality view" wise it performed very well and I
recommend a good 6" MN to anyone who wants a 6" APO but can't afford one, as
long as you have the mount to take it and don't mind the cool-down time. The
biggest disappointment with the MN was the relatively poor performance on
deep-sky. I thought the increase in aperture from 85mm to 150mm would be
significant on deep sky objects. WRONG! The difference between the TV-85 and
6" MN was much less than I would have thought. I knew at that moment that
any 5" or 6" APO was not going to satisfy my DSO aspirations, so I bought a
12.5 Portaball. Now I have what I consider to be an excellent setup; the
TV-85 for quick setup/quick looks and the highly portable 12.5 Zambuto
reflector for dark sky DSO's. Now I have to admit that I'm still lusting for
a 5" or 6" APO, but only for specialized planetary viewing. I know that such
a "nitch" scope will not quench my thirst for aperture.
Just my experience for whats it worth.
Gary
Deane Clark
> Deane:
>
> Like you I love my TV-85 but found I was quickly lusting for more aperture.
> I initially bought a 6" Mak-Newt thinking it was a cheap and easy way to get
> "big aperture" performance. "Quality view" wise it performed very well and I
> recommend a good 6" MN to anyone who wants a 6" APO but can't afford one, as
> long as you have the mount to take it and don't mind the cool-down time. The
> biggest disappointment with the MN was the relatively poor performance on
> deep-sky. I thought the increase in aperture from 85mm to 150mm would be
> significant on deep sky objects. WRONG! The difference between the TV-85 and
> 6" MN was much less than I would have thought. I knew at that moment that
> any 5" or 6" APO was not going to satisfy my DSO aspirations, so I bought a
> 12.5 Portaball. Now I have what I consider to be an excellent setup; the
> TV-85 for quick setup/quick looks and the highly portable 12.5 Zambuto
> reflector for dark sky DSO's. Now I have to admit that I'm still lusting for
> a 5" or 6" APO, but only for specialized planetary viewing. I know that such
> a "nitch" scope will not quench my thirst for aperture.
>
> Just my experience for whats it worth.
> Gary
Thanks Gary,
Your situation sounds very familiar. You aren't the only one suggesting the mid size
Dobs, of course - you guys are bringing me back to where I was a few months ago when I
went shopping for a 10 or 12 inch Dob. Got lots of recommendations for the Portaball and
Starmaster, and started quite a thread on the merits of Zambuto mirrors.
So, now that I'm back on the fence, how much does a 12.5 Portaball weigh? Will the mirror
ball fit in the trunk of a mid-size car? How available are they?
I'm also investigating fans for my MK67, so maybe I'll end up with a TV-85 for
quick/travel, 150mm Mak for planets, and a 10 or 12" Dob for DSOs.
Hope it's clear and dark where you are. Raining for the 13th day out of the last 14 here.
Deane Clark
clark...@qwest.net
Deane Clark
Thanks for the very on-topic and detailed response. Seems like everyone else is trying to
convert me to a Dob man. They may be right, but if I get a 5 inch "APO", the 125ED sounds
like the one.
Deane Clark
clark...@qwest.net
Deane Clark
Thanks for the recommendation, John. Portaballs certainly come highly recommended. I
responded to a similar recommendation by Gary Irwin today, so I won't repeat that here.
Deane Clark
clark...@qwest.net
Tony Flanders
> I'm also investigating fans for my MK67, so maybe I'll end up with a TV-85 for
> quick/travel, 150mm Mak for planets, and a 10 or 12" Dob for DSOs.
Just in case you have any false expecations: the MK67 may have its place,
but on a steady night, the planetary images from a 12.5" Zambuto mirror
will blow any 6" scope with a 33% obstruction completely and totally
out of the water. General consensus is that for planetary viewing,
the MK67 is closely comparable to a first-rate 4" APO.
- Tony Flanders
Gary Irwin
> Your situation sounds very familiar. You aren't the only one suggesting
the mid size
> Dobs, of course - you guys are bringing me back to where I was a few
months ago when I
> went shopping for a 10 or 12 inch Dob. Got lots of recommendations for
the Portaball and
> Starmaster, and started quite a thread on the merits of Zambuto mirrors.
>
> So, now that I'm back on the fence, how much does a 12.5 Portaball weigh?
Will the mirror
> ball fit in the trunk of a mid-size car? How available are they?
>
> I'm also investigating fans for my MK67, so maybe I'll end up with a TV-85
for
> quick/travel, 150mm Mak for planets, and a 10 or 12" Dob for DSOs.
>
> Hope it's clear and dark where you are. Raining for the 13th day out of
the last 14 here.
>
> Deane Clark
> clark...@qwest.net
Hi again Deane:
First, permit me to apologize for being a bit off topic and not answering
your initial posting directly. There are many excellent reasons why a 125mm
APO et.al. could be an excellent choice for you. Its just that I tuned in
to your desire for more aperture and thought "yep, been there, done that"
and went from there. For me, a newcomer to amature astronomy, I didn't
comprehend the cerebral knowledge that increments of single orders of
magnitude require a huge 250% increase in light gathering. Accordingly,
simple mathematics dictates that small increases in aperture do not
translate to significant increases in visual performance. I don't mean to
infer that you are inexperienced as I was/am I, just wanted to relate my
experience. Frankly, I'm often amazed at the debates and detailed
comparisons of fine APO's over a few mm or fractions of inches of aperture
that really mean nothing in the bigger scheme of visual astronomy, but I
digress...
As to your questions, all of the specs for Portaballs can be found on Peter
Smitka's Mag1 web site www.mag1instruments.com. My 12.5", which is balanced
for heavy eyepieces, weighs 60 lbs. The fiberglass ball, which includes the
upper tube assembly, is 24" in diameter and 20" high and will easily fit in
any car you care to name. The same scope is also available in a 14.5".
Availability, like all scopes containing Zambuto mirrors, is essentially
limited to the availability of mirrors from Carl Zambuto. Of course you
should check with Peter Smitka, but I would guess that 6 months is a good
starting guess.
Your plan for the TV-85 as a travel/quick look, 10"+ dob for DSO's and 6"
something for planets is fine - just make sure you get the dob next!
(assuming it fits your lifestyle). A high-quality medium-to-big aperture dob
will "crystalize" ones understanding of the limitations of small aperture
scopes - fine instruments though they may be.
Good luck!
Gary Irwin
Siegfried Gonzi
Tony Flanders schrieb:
> Just in case you have any false expecations: the MK67 may have its place,
> but on a steady night, the planetary images from a 12.5" Zambuto mirror
> will blow any 6" scope with a 33% obstruction completely and totally
> out of the water.
That is not a surprise. A 12.5" mirror will also show color on Saturn's rings. I once
owned a MK 67 Maksutov but was not able to see any color ever at Saturn or Jovian. But
I saw color with a 14" newton (a friend of mine has got such a thing).
> General consensus is that for planetary viewing,
> the MK67 is closely comparable to a first-rate 4" APO.
Or better.
Has anybody ever seen color with a first-rate 4" or 5" Apo on the planets?
S. Gonzi
Siegfried Gonzi
ccwoodruff schrieb:
> Hello,
> I have the Borg 100ED, I tried the Borg 100 Achro and after my buddy and I
> took my ED out he went and bought a Borg 125ED. Comparing my 100ED to
> the TV85 & TV101 the Borg weighs the same as the TV85. It is also the same
> size as the TV85. The TV's are very slightly sharper.
Sorry but can you elaborate. It sounds strange for me that the ED 100 is not as
sharp as an TV85. Are you sure that you was in-focus during your observing? Did
you observe and compare the two scopes with the same class of eyepieces.
> The TV's are 3% better
> optically, if
> I didn't have them side by side I don;t think I would know the difference.
3% ? How can someone judge 3%?
> The
> same was true with the Borg125ED. Basically no color in focus, nice and
> sharp.
You wrote above that the ED is not very sharp.
How often did you compare the two scopes?
I am not a proponent of any Borg refractors neither TV but people often bild-up
an opinion based on a look-through only.
S. Gonzi
Bill Mette
--
| "Instead of letting the moon be the
Bill Mette | gateway to our future, we have let
Enteract, Chicago | it become a brief chapter in our
| history." - Andrew Chaikin
Deane Clark
> Has anybody ever seen color with a first-rate 4" or 5" Apo on the planets?
>
> S. Gonzi
This seems an odd question. I see color every time with my TV-85 on Jupiter and Saturn.
The colors are shades of pale yellow, orange, and brown. I don't mean to be nosy, but do
you have a mild color blindness which can be overcome if the image is bright enough? Are
we talking about the same type of "color"?
Deane Clark
clark...@qwest.net
Cindy Quek
The review does mention that a 5mm Tak was used on the TV85 and a
4.8mm Nagler on the Borg 100ed although personally I'm not sure how
the eyepieces compare but they might be a factor.
yours
Cindy
On Sat, 16 Jun 2001 12:14:04 +0200, Siegfried Gonzi
<siegfri...@kfunigraz.ac.at> wrote:
>Sorry but can you elaborate. It sounds strange for me that the ED 100 is not as
>sharp as an TV85. Are you sure that you was in-focus during your observing? Did
>you observe and compare the two scopes with the same class of eyepieces.
_
Urban Astronomer
http://www.stargazing.net/urban
Sandy Crane
> I have the Borg 100ED, I tried the Borg 100 Achro and after my buddy and I
> took my ED out he went and bought a Borg 125ED. Comparing my 100ED to
> the TV85 & TV101 the Borg weighs the same as the TV85. It is also the same
> size as the TV85. The TV's are very slightly sharper. Splitting doubles
I am thinking about buying the 100mm Borg achro because of its
significantly lower price compared to the semi-apo. You say that you
tried the achro. I am interested in the achro as a third scope between
a 6" mak-newt and a Ranger. I am primarily interested in resolution,
contrast, and the ability to push magnification to about 200x. I am
not bothered by color excessively, but I would occasionally like to
view the moon and planets without being totally distracted by false
color. I wonder if you could characterize your experience with the
Borg achro as to its optical qualities. Thanks, Sandy Crane, Boise,
ID.
ValeryD
> I'm a TV-85 owner who is very happy, but getting a craving for a larger refractor.
> jump in aperture to make it worth another $2.2K for the TV-102 (for example).
>
> I've recently realized what a good deal the Borg 125ED seems to be relative to other 5
> inchers out there.
>
> Does anyone have any experience with this scope, and maybe specifically how it compares to
> the TV or Tak 4 inchers? Are the Borg EDs as color corrected as a TV-85?
> If you have one of these, how do you like the helical focusser?
> What added cost accessories do you feel are required, assuming use with a 2 inch star
> diagonal?
> Finally, how quickly can a person get one? I hope the line isn't AP-like.
>
> TIA,
>
> Deane Clark
> clark...@qwest.net
Deane,
I got a 125mm F/8 ED BORG. It is a good instrument with its own advantages
and disadvantages.
advantages:
1. Very lightweight
2. High contrast optics (only two lenses).
3. A lot of available accessories.
4. Precise helical focuser very suitable for wide field fotography
(I do mean 4" focuser).
Disadvantages:
1. Not the best color correction. Bright stars and Venus will show
some residual violet.
If you will observe Mars, you will not be able to come to a snap
focus without a filters. With mine, I always felt, that I can't
reach a true sharp image of Mars. The reason is that BORG has not
the best color correction in a red part of spectrum. Using green,
green-yellow, orange and red filters I was able to see a very sharp
Mars images.
However, my 125mm F/8 BORG show sharp and color-free images of moon,
Jupiter and Saturn.
2. The cell of the objective has four (???) centering allen screws.
It was a real headache to center lenses when the objective lost its
collimation.
I don't know if a new BORGs has better glass combination(s) than mine,
but I am not sure, that 125mm F/6 model ( F/8 was discontinued?) has
good enough color correction to exceed or even be equal to one in mine.
You decision which scope to buy next should be based on your own preferences.
I can rate the BORG as a typical middle-end apo. I will replace an objective
in my scope for a fluorite doublet.
Valery Deryuzhin.
Deane Clark
Valery,
Thanks for the first hand info. I am not really sure how much color I am willing to
tolerate. I only have experience with the TV-85 and that has essentially no color
in-focus, green/violet tinge on either side of focus. It is hard to say how it performs
on Mars due to its low altitude, but it seems to me my 150mm Mak had a sharper image of it
last night. This amount of color doesn't bother me at all, so If I knew the Borg 125ED
had similar performance, I would feel comfortable ordering one. I would like to try out
some other nice refractors first at star parties, but my local club seems a little
refractor deficient (unless you count ST80s).
Does your last comment mean that Borg has an available fluorite objective, or just that
you would upgrade if it WAS available?
Deane Clark
clark...@qwest.net
Siegfried Gonzi
Sandy Crane schrieb:
> I am interested in the achro as a third scope between
> a 6" mak-newt and a Ranger. I am primarily interested in resolution,
> contrast, and the ability to push magnification to about 200x. I am
> not bothered by color excessively, but I would occasionally like to
> view the moon and planets without being totally distracted by false
> color.
I do not own the Borg achro 100mm, but I owned a Vixen Fraunhofer achro 100mm (with f1/10). Color
was severe. The contrast wasn't better than my ETX 90 on the planets (it is equal or likely better
than a Pronto concerning contrast).
It is clear that the Mak-Newton outperforms the 100mm Borg. The 6" Mak-Newt is more close to an
5inch apochromat.
With the Borg 100 you can expect a contrast performance of a good 7 or 7.5cm apochromat.
That means maybe you are better off with the Borg ED 7.5cm?
S. Gonzi
ValeryD
> Thanks for the first hand info. I am not really sure how much color I am willing to
> tolerate. I only have experience with the TV-85 and that has essentially no color
> in-focus, green/violet tinge on either side of focus. It is hard to say how it performs
> on Mars due to its low altitude, but it seems to me my 150mm Mak had a sharper image of it
> last night. This amount of color doesn't bother me at all, so If I knew the Borg 125ED
> had similar performance, I would feel comfortable ordering one. I would like to try out
> some other nice refractors first at star parties, but my local club seems a little
> refractor deficient (unless you count ST80s).
>
> Does your last comment mean that Borg has an available fluorite objective, or just that
> you would upgrade if it WAS available?
>
> Deane Clark
> clark...@qwest.net
Deane,
As I wrote, I can't advice a BORG if your preference is planets observing.
While giving sharp and color free images (in focus) of moon, Jupiter and
Mars, a 125mm F/8 BORG can't deliver really sharp image of Mars.
For general use, for wide field photography this scope is very good and
probably one of the best compromised solution, especially due to its
small weight and excellent helical focuser. But, I believe, there are
another better choices for planetary observing fans.
I will replace an objective in my scope by objective made in ARIES.
It will be fluorite doublet and totally color free (for eye).
I should note, that F/6 model will has at least 2x larger color error
than F/8 model - assume both use the same glass combo. So, if you will
decide to buy BORG in any case, try to find one with F/8 if a visual
observing is your main goal. For wide field photography F/6 is the
choice.
Best,
Valery Deryuzhin.
Siegfried Gonzi
Deane Clark schrieb:
> This seems an odd question. I see color every time with my TV-85 on Jupiter and Saturn.
> The colors are shades of pale yellow, orange, and brown. I don't mean to be nosy, but do
> you have a mild color blindness which can be overcome if the image is bright enough?
Yes I see color (or better I saw color) on the planets with the 6" Maksutov and even with my
ETX 90. But that is the sort of color which is very hard to judge. I wasn't in the position
to really say: "Yes I saw brown bands on Saturn". It was more on the edge to vagueness.
But with the big Newton it was really obvious that I saw color on Saturn (side by side
compared with the 6" Mak; Saturn was high).
I only once had the situation were I really saw color with the Mak 6", that was when Jovian
was about to setting and near the horizon.
How great a the chance with a TV-85 that it shows some sort of ghost-color. I mean is it
possible when someone sees for example red bands on Jovian that this "red" is due to the
apochromat (even a good apochromat is not absolutely color-free) and not due to color in
nature?
But I will notice in my record that I should take care that people also with small scopes see
color.
S. Gonzi
Siegfried Gonzi
ValeryD schrieb:
> As I wrote, I can't advice a BORG if your preference is planets observing.
> While giving sharp and color free images (in focus) of moon, Jupiter and
> Mars, a 125mm F/8 BORG can't deliver really sharp image of Mars.
Please elaborate what makes Mars so different?
> But, I believe, there are
> another better choices for planetary observing fans.
>
Yes, and that is not a refractor. Even a 8" Schmidt-Cassegrain will deliver what you want.
S. Gonzi
ValeryD
> ValeryD schrieb:
>
> > As I wrote, I can't advice a BORG if your preference is planets observing.
> > While giving sharp and color free images (in focus) of moon, Jupiter and
> > Mars, a 125mm F/8 BORG can't deliver really sharp image of Mars.
>
> Please elaborate what makes Mars so different?
Mars has much more orange-red in its spectra. And not well focused
orange and light red and red together produce not very sharp image.
Image, of course is significantly sharper than even in 6" F/10-12
achromat, but still nots as sharp as in APOs with better color correction.
>
> > But, I believe, there are
> > another better choices for planetary observing fans.
> >
>
> Yes, and that is not a refractor. Even a 8" Schmidt-Cassegrain will deliver what you want.
You are not right. I do mean another apos and Maks. Never SCT !
The only SCT which, as I heard, is suitable for planetry observing
is TAK one. Very rare Netherland's Opticom 10" F/15 SCT with
25% c.o. Meade and Celestron are not the best choices for visual
planetary observing. Only for CCD they are acceptable.
Valery Deryuzhin.
Eric Strang
<<I am thinking about buying the 100mm Borg achro because of its
significantly lower price compared to the semi-apo. You say that you
tried the achro. I am interested in the achro as a third scope between a
6" mak-newt and a Ranger. I am primarily interested in resolution,
contrast, and the ability to push magnification to about 200x. I am not
bothered by color excessively, but I would occasionally like to view the
moon and planets without being totally distracted by false color. I
wonder if you could characterize your experience with the Borg achro as
to its optical qualities.>>
Hi Sandy-
I have a Borg 100 achro. I use it as my grab and go scope. Image quality
is excellent, the lens is very sharp. The detail it shows on Jupiter and
Saturn is outstanding, much better than what you would expect for a fast
achromat. I've used it so far to 128x with excellent results. Yes, there
is quite bit of false color, but this doesn't bother me as this is just
a scope for those quick views. If you are not bothered by the false
color I'd say get one.
Eric Strang
Cheney, Washington
Astro Page
http://community.webtv.net/eric719/TheStrangListDeep
Deane Clark
I suppose it is possible that with more aperture, the color might look more saturated, but
I have no first-hand experience with this. We'll see this fall when I should get the
chance to look at Jupiter and Saturn in some big dobs. I am looking forward to it!
As for the colors I see in my TV-85, I don't believe there is any reason why a scope which
shows no color fringe on bright objects should introduce color error into a planetary
disk. So, I do not doubt that the colors I see are real. I suspect that different
observers have varying sensitivity to pale color and distinctions of shade, so maybe the
image in a small scope really does look "black and white" to some people. Also, Tele Vues
are famous for excellent contrast, and that would tend to make colors more apparent.
Finally, when anything is near the horizon, the colors would be less accurate due to
atmospheric refraction and reddening from atmospheric dust.
Deane Clark
clark...@qwest.net
Deane Clark
> Valery Deryuzhin.
Valery,
How old is your 125ED f/8?
Dale Ibis, are you out there?
Can you comment on the optical differences between the 125ED f/8 and the current 125ED
f/6.4? Are the newer models better corrected? I'd hope so, since Borg is selling both an
f/4 and an f/2.8 version as well!
Thanks,
Deane Clark
clark...@qwest.net
Sandy Crane
Yes, the Mak-Newt is a great scope, but between it and the mount its a
project to set up. What I want is something I can leave on a tripod
with a geared head to take out whenever I feel like it. I don't expect
the quality of the 6", neither do I want to be reminded that the scope
is a compromise every time I use it. I like the ranger because it is
sharp and secondary color is not bad. I'm just greedy and want a
little more aperature than its got. You're probably right about the
Borg 75mm ED being the better scope, plus being a better bargain.
Sandy
Sandy Crane
Eric
Thanks for your reply.
Thanks for the info. I appreciate your straightforeward opinion.
Sandy.
Cindy Quek
Jumping in here on the issue of seeing colour, I distinctly saw saturn
as a creamy pale yellow with my 6" newt, is it that hard to see colour
then or do you guys mean something else?
cindy
Tom Luttrell
blue/violet smear on other side of bright objects. It's due to the
lenses acting like prisms, splitting white light into its components.
Antispam email address: please remove [.antispam] to reply
http://www.users.bigpond.com/tom.lut/
Siegfried Gonzi
> Hi
>
> Jumping in here on the issue of seeing colour, I distinctly saw saturn
> as a creamy pale yellow with my 6" newt, is it that hard to see colour
> then or do you guys mean something else?
Do you see the band on Saturn in colour?
With my ETX the Saturn itself is also pale. The Fraunhofer achromat
refractor shows Saturn strong yellow (that is due to secondary colour).
S. Gonzi
Tom Luttrell
like this.
They were actually talking about the ease of seeing the colour of
celestial objects.
I have no trouble seeing the difference in colour of the equatorial
band to the rest of Saturn with my 4" APO.
Cindy Quek
I remember the band being paler than the rest of the planet but I
cannot remember exactly the colour as it has been quite some time,
sorry. My memory tells me it was a pale cream, not white or grey but i
could be wrong.
cindy
_
Urban Astronomer
http://www.stargazing.net/urban
Deane Clark
Hi Siegfried,
The band on Saturn, to me, looks brownish against the overall pale yellow color.
I think that the secondary color one sees in an achromat (or any refractor) should not
cause the whole disk to appear an unnatural color, but rather just the edges of the bright
disk. Within the disk, at a distance from the edge greater than the prismatic "smearing"
of the light, the overall color should be the same, since the reds from one area would be
combined with the violet from an adjacent area. This effect would, however, obscure
detail within the disk. This is exactly the effect one would see looking at Mars when the
telescope has secondary color. The image still has the general orange color of the
planet, but the details do not come to a sharp focus.
Were you looking at Saturn when it was close to the horizon? That makes any planet look
very yellow.
In any case, we aren't trying to make you feel bad about what you see. You should use
whatever telescope gives you the most pleasing view for you.
Deane Clark
clark...@qwest.net
Deane Clark
Dale Ibis, sales rep for Hutech, answered me privately, so as not to give the appearance
of advertising on SAA, so I thought I'd repeat his response here.
Quoting...
----------------------------
"It has been pointed out to me that you asked me a question on the Sci.Astro.amateur
disussion group. I am not registered with Sci.astro.amateur because I feel it is a
discussion group, not an advertising forum, so I am responding to you privately.
You asked whether the new Borgs are corrected any better than the older Borg. Both the
older and the newer Borgs have excellent color correction both visually and
photographically. The scope that Mr. Deryhuzin uses has a spot size in the Fraunhofer C
line (red) that is considerably smaller than the airy disk of an f/8 scope.
This means that the color error cannot be seen. Perhaps the difficulty Mr. Deryhuzin had
with viewing Mars has nothing to do with the telescope, but instead is due to something
else. Mars is a notoriously difficult object to view. Most observers find that the use
of color filters considerably enhances views of Mars. I know I
find color filters helpful even when viewing with reflectors.
As for the current crop of Borg Scopes, they enjoy the same level of excellent color
correction as did the older models, and in some wavelengths, the color correction is
considerably improved. Because the new model is an f/6.4 instead of f/8, the lens design
has been optimized for that focal ratio. The shorter focal
ratio improves photographic capability and wide field visual observing. Borg's excellent
spherical correction and smooth figure provides clear, sharp images of the moon and
planets.
The best test of all is to view through a 125 ED yourself. I believe you will be very
impressed as I was when I first used a Borg telescope. You can do this by attending
astrofest in September where I will have examples of Borg scopes for your trial or by
ordering a Borg. If you are not satisfied, you can send it back.
Last, the f/4 and f/2.8 versions are designed for wide field photography with large format
cameras. Again, if you attend astrofest you can see some of the photos taken with these
fine instruments. Star images are sharp across a very large field and free of the blue
halos found on short focal length achromats.
I hope this answers your questions.
Dale Ibis
Hutech Astronomical Products"
----------------------------
So, take this for what it's worth. I hope Dale doesn't mind me quoting him here.
Deane Clark
clark...@qwest.net