Unitron refractors??
Chunga
experience/opinions about the overall quality and value of the scope. In a
brief conversation I gathered it was 4-4.5" and had a focal length of 700mm
(1980's ?). He seems happy with it but wanted to know what his was worth. He
claims it has razor sharp views of planets even at high powers. Does he have
a good scope? How much would he have to spend to upgrade beyond his Unitron.
(he doesn't use the internet or else I'd tell him about SAA and have him ask
himself).
Thanks
-Tim
Etok
"Chunga" <Chu...@Revenge.bark> wrote in message
news:0WJN9.76203$hK4.6...@bgtnsc05-news.ops.worldnet.att.net...
I had one 25 years ago. It was a 90mm, as I recall. Equatorially mounted.
It is the first telescope I owned that enabled decent views of Saturn.
Your friend has a good scope, imho. I cannot recall ever seeing any false
color
in my Unitron.
Etok
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Rod Mollise
>color
>in my Unitron.
Hi:
Maybe he has a good scope. I can't every recall seeing a Unitron with this
small a focal ratio (700mm=f/7). If so, it will show a goodly amount of color.
Peace,
Rod Mollise
Author of _Choosing and Using a Schmidt Cassegrain Telescope_
Like SCTs and MCTs?
Check-out sct-user, the mailing list for CAT fanciers!
Goto <http://members.aol.com/RMOLLISE/index.html>
Paul A Brierley
S&T in the 1970 s and 1980s. There telescopes looked very well made,
and I always wish I owned one back then. Any way I did a search
using Copernic and I found these web pages.
http://home.att.net/~telescopebluebook/refractor/unitron.htm and
http://www.astromart.com/messages.asp?message_id=2782 and also
http://www.unitronusa.com/quick_look_teles.htm
Merry Christmas.
PaulB..
Rich N.
> How much would he have to spend to upgrade beyond his Unitron.
>(he doesn't use the internet or else I'd tell him about SAA and have him
ask
>himself).
>
>Thanks
>-Tim
Upgrade in size? Upgrade in optics? Both?
He could find better optics with a used Celestron SPC102F
(a 4" f/9 fluorite doublet APO). They should be under $2k.
Dittos with a Takahashi FS-102 (4" f/8 fluorite doublet) some
can be found for under $2k.
He could get a 5" (or larger) APO refractor. Maybe a used
Tak. FS-128 for under $4k.
He could get a 1990s or later Celestron C8 SCT. It would be
a big jump up in aperture. If he collimates it correctly it should
show more planetary detail than his 4" Unitron achromat. He
would also need to let the C8 sit outside for about an hour to let
it settle to the outside temperature.
The "seeing" (stability of the image because of our atmosphere)
in your location will make a huge difference in how well any telescope
performs on viewing planets.
Single tube Dobs (6", 8" 10") give you a lot of bang for the buck.
Orion and a number of other companies sell them.
Rich
Etok
I fell asleep reading "Choosing and Using..." last night.
I actually bought a copy.
But my "Seeing in the Dark" is *signed*..
LOL.
Etok
"Rod Mollise" <rmol...@aol.com> wrote in message
news:20021223153709...@mb-cn.aol.com...
______________________________________________________________________
JBortle
cobbled together item using some Unitron parts, as I don't recall them ever
making any scopes that weren't pretty close to f/15. If truly a Unitron 4" of
f/7, I suppose it might just possibly have been a "special" for use as a guide
or photographic scope in conjunction with their huge 6" photo-equatorial
refractor. Did it come with a matching Unitron equatorial mounting or is it
just a tube assembly?
John
Alan French
think could easily be mistaken for a Unitron. There was also a 130mm f/8
but it had a bluish colored tube. The mountings also appear very similar to
those offered by Unitron.
Clear skies, Alan
"JBortle" <jbo...@aol.com> wrote in message
news:20021223225509...@mb-cj.aol.com...
chrisachroisdk
You may like to ask here:
http://groups.yahoo.com/group/UnitronTelescopes/?guid=1000228709
Chris.B
Rod Mollise
>think could easily be mistaken for a Unitron. There was also a 130mm f/8
>but it had a bluish colored tube. The mountings also appear very similar to
>those offered by Unitron.
Hi Alan:
Yep..I'd forgot about those. Meade also sold 4" refractors made from the same
parts Unitron used (Japan). All of the Meades were long focal length, however.
Rod Mollise
>I actually bought a copy.
>But my "Seeing in the Dark" is *signed*..
>LOL.
Bring me a bottle of Rebel Yell and I'll sign anything (ask my ex-wives) :-)...
JOHN PAZMINO
C > Subject: Unitron refractors??
C > Date: Mon, 23 Dec 2002 19:58:52 GMT
C > Organization: AT&T Worldnet
Ur won't be 4 inch aperture with a 700mm focal length! If the FL
is correct, the instrument may be 60mm aperture.
On the whole Unitrons were the Cadillac of scopes in the 1950s
thru the 1970s. The mechanics were cheaoly made, yet they were better
than most other small scopes of the era.
Unitron is STILL IN BUSINESS on Long Island! It's STILL SELLING
the SAME scopes with virtually NO update or evolution.
C > A friend has a Unitron refractor and was wondering if anyone had any
C > experience/opinions about the overall quality and value of the scope. In a
C > brief conversation I gathered it was 4-4.5" and had a focal length of 700mm
C > (1980's ?). He seems happy with it but wanted to know what his was worth. He
C > claims it has razor sharp views of planets even at high powers. Does he have
C > a good scope? How much would he have to spend to upgrade beyond his Unitron.
C > (he doesn't use the internet or else I'd tell him about SAA and have him ask
C > himself).
---
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Rod Mollise
>the SAME scopes with virtually NO update or evolution.
Hi:
Nor any decrease in prices. And they also feature the "incredible shrinking
product line." I mean, you can't even get a Duetron or a Unihex these days!
SHEESH! :-)
Barry Simon
> C > From: "Chunga" <Chu...@Revenge.bark>
> C > Subject: Unitron refractors??
> C > Date: Mon, 23 Dec 2002 19:58:52 GMT
> C > Organization: AT&T Worldnet
>
> the SAME scopes with virtually NO update or evolution.
>
Let me clear up a few misconceptions about Unitron -
Yes, they were considered the Cadillac of refractor telescopes,
basically from when they started in 1952 up to about the mid-80's when
APO refractors hit the market. Current top quality APO refractors in
shorter focal lengths will outperform a Unitron. For example a TAK
FS78 f/8 will do better than a 3" f/16 Unitron, plus the TAK has a
much nicer focuser and is more portable with a shorter tube length.
Yes, Unitron Instruments is still in business, but it has been bought
and sold several times. Contrary to what the Unitron web site would
have you believe, Unitron telescopes in the standard 60mm, 75mm and
102mm sizes ARE NOT AVAILABLE. The supplier of the components (in
Japan) got out of the telescope business several years ago. The same
parts (focusers, objective cells, hinge rings, etc.) were made
available to Polarex (basically a Unitron in Europe) and to
Vernonscope for the Brandon APO 94's and 130's (the 94 used Unitron 4"
components and the 130 used Unitron 5" components). Try ordering a
Unitron telescope new, you cannot get one. Unitron has a very limited
supply of spare parts for existing scopes and many parts are simply
not available.
Meade refractors were not Unitrons. The Meade 3" model 300 which is
an 80mm f/15 is the same telescope as one distributed by TASCO and
also available under the TOWA label. The Unitron 3" is a 76mm
objective with a 75mm aperture and it has a f/16 f-ratio. A close
comparison of the components (tube hardware and the mount) show them
to be very different. Same thing with the Unitron 4" in comparison to
the short-lived Meade 4". They are similar in that they are both 4"
f/15 in white tubes, but beyond that there are a number of
differences.
Unitron's bread and butter equatorial refractors were the Model 128
60mm f/15, the Model 142 75mm f/16 and the Model 152 102mm f/15.
These tube assemblies were also available on some very nice
alta-azimuth mounts. Unitron also made a very nice 5", 6" and a very
rare 8" refractor in typical long focal length (f/15 to f/16
configurations. They also had 60mm guidescopes that had 700mm focal
lengths and some early alta-azimuth 60mm scopes with this focal
length. In the mid 80's they did introduce a 500mm focal length 75mm
f/6.7. I had one and it was remarkably color free. Peter Cerravalo
tested this scope at the 1992 (or was it 1994) Texas Star Party and
commented very favorably about it's optical quality. This scope was
the "grandfather" of all the short tube 80mm refractors that became
popular in the 90's.
Another Unitron that developed quite a following was the 3" folded
light path refractor. At first glance it looks like a short
reflector. Rent the remake of "Invaders from Mars" with Karen Black.
This scope can be found in the boy's room. There was also a 4"
version of this scope, it was not available for very long.
Many have the opinion that the best all-around performing Unitron was
the 3" f/16 model 142. From the early 70's on the Unitron objective
cell had 3 external ears which allowed for precise collimation. When
well collimated this scope was virtually color free and extremely
sharp. In my personal experience (25+ years and 40+ telescopes) it
would typically compete very well with 8" Schmidt-Cassegrains and will
blow away any Questar 3.5" Mak. A well cared for 3" Unitron in
excellent condition and with equatorial mount can fetch between $1200
and $1800 on the used market.
The web address for the Unitron Yahoo Group can be found two messages
up. I am it's moderator.
Barry Simon
Alan French
A very interesting and informative post, but your claim that a 3" refractor
will compete very well with an 8" SCT flies in the face of physics and my
experience. A quality 3" achromat is a fine instrument, but there is
nothing magical that will enable it to outdo a telescope of good quality
with more than twice the aperture. Even allowing for the central
obstruction, the jump from a 3" to an 8" scope is quite significant.
I started this hobby with a 2.4" Unitron in 1965, and it was rather
handicapped by its aperture. Our 3.5" Questar, which was a much later
acquisition but did not have any of the modern coatings, did a little bit
better than the 60mm Unitron. I doubt very much that a 76mm refractor would
"blow away" a quality 90mm Mak.
Clear skies, Alan
"Barry Simon" <bsim...@aol.com> wrote in message
news:989139d7.02122...@posting.google.com...
> [SNIP]
John McVey
130mm refractor "blew the doors of it".
John
Alan French
No, I don't want a war <g>, but claims that a 3" scope beats out an 8" seem
quite a bit of a stretch. In your case, you have a bit more aperture, but
it seems likely something was amiss with the SCT if your Brandon 130mm
really "blew the doors off it." What vintage was your SCT? The SCTs being
produced today seem pretty decent, but there were some back in the 1980s
that were pretty poor optically.
Clear skies, Alan
"John McVey" <jrm...@cableone.net> wrote in message
news:3E0A2B01...@cableone.net...
Barry Simon
> Barry,
>
> A very interesting and informative post, but your claim that a 3" refractor
> will compete very well with an 8" SCT flies in the face of physics and my
> experience. A quality 3" achromat is a fine instrument, but there is
> nothing magical that will enable it to outdo a telescope of good quality
> with more than twice the aperture. Even allowing for the central
> obstruction, the jump from a 3" to an 8" scope is quite significant.
Alan,
If you reread my post what I said was that it (3" Unitron f/16) would
compete very well with an 8" Schmidt-Cassegrain, nothing more.
Specifically, while I did not say it in the earlier post, this was in
regard to observations of the Moon, planets and double stars. It was
not in reference to observation of faint deep sky objects.
I am willing to bet that many amateur astronomers are sometimes
limited to relatively short observation sessions. Given this
condition, a modest refractor of 3" often has a decided advantage over
compound telescopes larger in size that often are not really "ready"
for serious observing sessions until they have settled down. If that
settling down process takes 45 minutes to an hour, that is time wasted
and time that often does not exist if observing sessions are short.
Even when well collimated and equalized, I have found that the typical
8" Schmidt-Cass cannot hold more than 40x per inch very well. Often
the limit is closer to 30x per inch and this is with excellent
collimation and after the scope has settled down. So a 3" refractor
which often performs very well at 80x to 100x per inch and an 8"
Schmidt-Cassegrain are often maxed out at very close to the same upper
magnification. Over the 10 years that I owned an 8" Meade 2080 this
was always disappointing to me. After I purchased a 4" Unitron back
in 1986 and saw what clusters could really look like I lost interest
in the Meade except for use as a piggyback guiding platform. It was
eventually sold in 1993. As I said, I have found that a good
achromatic refractor can often be pushed to 100x per inch. With the
Takahashi and Brandon APO refractors that I own, I find that I can not
only pull 100x per inch out of these scopes but I can have excellent
color fidelity too on objects like Sirius, Venus and the limb of the
Moon.
I do find that I can pull 100x per inch from my Intes MK67 Deluxe with
Sital optics. It does require proper settling down to do this. It
cannot be done on most nights within the first half hour or so of
setting up.
Getting back to the performance of the Unitron. It did and does what
I said it could do. A friend that bought the 3" Unitron after I got
my 4" Unitron subsequently sold a 12.5" Dob after he got the 3". He
also later bought a Questar on condition that if it did not outperform
his Unitron he could return the Questar. The first dealer he
contacted upon hearing this refused to sell him a Questar under this
condition. A second dealer was so confident that the Questar would
outperform the Unitron that he agreed to the terms. Boy was he
surprised when my friend called a few weeks later and said that he
could not justify keeping a $3000 telescope that was just marginally
better on small open clusters and slightly worse on the planets in
comparison to the $700 Unitron. The Questar went back.
An excellent Unitron (3" and up) was and is an outstanding performer
on the Moon, planets and double stars. It is not the instrument of
choice on more than a few deep sky objects. It does often compete
very well with good 8" Schmidt-Cassegrains on solar system objects and
in my opinion it is a better
all around performing optical system in terms of pure performance than
a 3.5" Questar. If limited to short observing sessions from home (4.5
to 5th magnitude suburban skies at the zenith under the best of
conditions) a good 3" f/16 achromatic refractor would be all I would
need. Starting from scratch today and limited to just one telescope
for all uses, purchased new, it would be a 3" to 4" APO refractor from
either Takahashi or TeleVue.
Barry Simon
Alan French
I agree that a 3" refractor has a decided advantage over an SCT in terms of
cool down, but for someone who is not limited by time a modern 8" SCT is
going to reveal more planetary detail than a 3" Unitron. As I said before,
there is nothing magic about a Unitron - it is limited by its aperture just
like any other telescope.
From your description it seems your Meade SCT dates prior to 1986. In that
era I would not and did not recommend SCTs. They have come a long way since
then.
I don't know what your friend expected, but a 3.5" Questar should be a bit
better than a 3" achromat on some things, perhaps not on others. Your
friend found the Questar a bit better on small open clusters, and a bit
worse on the planets. What is so odd about that? If he expected the Q to
be significantly better than the 3" Unitron he did not understand
telescopes. The Questar is expensive because it is very well made, but the
price does not overcome the limitations of the 3.5" aperture.
I used a 4" f/15 Clark for several years, my wife owned a 4" Unitron for a
while, and she now owns a 4" APO, so I have a good idea what you can see
with a 4" refractor and how they compare with other scopes. My main
interest has been lunar and planetary viewing, and I find a well made 8"
scope a better choice than a 4". The particual design is far less important
than the quality of execution.
Clear skies, Alan
"Barry Simon" <bsim...@aol.com> wrote in message
news:989139d7.02122...@posting.google.com...
>
> If you reread my post what I said was that it (3" Unitron f/16) would
> compete very well with an 8" Schmidt-Cassegrain, nothing more.
> Specifically, while I did not say it in the earlier post, this was in
> regard to observations of the Moon, planets and double stars. It was
> not in reference to observation of faint deep sky objects.
>
> I am willing to bet that many amateur astronomers are sometimes
> limited to relatively short observation sessions. Given this
> condition, a modest refractor of 3" often has a decided advantage over
> compound telescopes larger in size that often are not really "ready"
> for serious observing sessions until they have settled down. If that
> settling down process takes 45 minutes to an hour, that is time wasted
> and time that often does not exist if observing sessions are short.
> [SNIP]
> Getting back to the performance of the Unitron. It did and does what
> I said it could do. A friend that bought the 3" Unitron after I got
> my 4" Unitron subsequently sold a 12.5" Dob after he got the 3". He
> also later bought a Questar on condition that if it did not outperform
> his Unitron he could return the Questar. The first dealer he
> contacted upon hearing this refused to sell him a Questar under this
> condition. A second dealer was so confident that the Questar would
> outperform the Unitron that he agreed to the terms. Boy was he
> surprised when my friend called a few weeks later and said that he
> could not justify keeping a $3000 telescope that was just marginally
> better on small open clusters and slightly worse on the planets in
> comparison to the $700 Unitron. The Questar went back.
> [SNIP]
DGM Optics
First congratulations to you and Sue on the IAU minor planet designation in
your honor!
Regarding this thread I most certainly agreed that a 3" (name the scope)
will not show as much detail on most objects as an 8" SCT, I would concur
with John McVey that a 5" unobstructed instrument (APO or, based on my own
experience, off-axis newt) is a whole other kettle of fish. I`m also in
agreement that most of the SCT`s of 10-15 years ago were awful in all ways,
but even the much improved SCT`s of the past few years still have pitiful
total optical thruput. Using 96% RX coatings x 3 surfaces (primary,
corrector secondary, and 45 degree diagonal) + corrector with high quality
BBAR (98% TX) they still have lost 15% at the focal plane not even including
the C.O.
Dan McShane
www.dgmoptics.com
"Alan French" <adfrenchre...@nycap.rr.com> wrote in message
news:PqqO9.131369$Vz2.32...@twister.nyroc.rr.com...
Mike Rogers
Alan, I have to agree with Barry I'm afraid that size is'nt always
what counts!! I have had an 10" Dob and more recently a Meade LX10 8"
SCT. The problem with both instruments was they hardly ever got out
into the garden as I nearly broke my back getting them out there. Any
yes - at least a 1/2 hour to settle down. Yes of course I should have
taken the tube and tripod out separately but that takes time to
assemble again and suprise suprise - the clouds have appeared out of
nowhere so thats it for the night! I now have what I consider my best
scope ever - and I have had a few. It's a 12 year old Televue Genesis
4" Flourite on a telepod mount. I look out my window - clear skies - I
am up out there and veiwing in less than 2 minutes. Optics are as good
as any large mirror I have had as I am in the city - but what I can
see is just so pin sharp - Lyra double double split at 70x - never did
that with the 8" SCT.
Happy new year
Mike
bsim...@aol.com (Barry Simon) wrote in message news:<989139d7.02122...@posting.google.com>...
W. Snell
SCT still gathers twice as much light as the 5" refractor (using your
numbers.) The SCT also has higher resolution.
The SCT is probably less expensive than the refractor.
"DGM Optics" <dgmo...@erols.com> wrote in message news:<aue41l$2i0$1...@bob.news.rcn.net>...
Barry Simon
> Barry,
> From your description it seems your Meade SCT dates prior to 1986. In that
> era I would not and did not recommend SCTs. They have come a long way since
> then.
Alan,
My 2080 was one of the early ones. It was purchased in July, 1982.
Yes, I have seen some outstanding optics on some Schmidt-Cass scopes.
A friend has a 8" Celestron dating from the late 70's/early 80's which
is the best I have ever seen. If I could be assured that I could get
an optical tube assembly of that quality I would snatch it up in a
second.
This leads us to the whole question of quality control and consistency
in any optical layout we may consider. It has often been said that
the Schmidt-Cassegrain is a great idea, but when executed for the
masses at a price point that the typical consumer is willing to pay,
some shortcuts are taken. Takahashi made a schmidt-cass about a
decade ago, the TSC 225; for tube assembly alone it was close to
$4000, the price you pay for a very well executed and virtually
optically perfect design. More importantly it was consistently
excellent. Unfortunately at it's price point not many have been able
to see what a truly excellent schmidt-cassegrain is able to do, only
100 were made.
Same thing applies to the current invasion of Chinese made refractors
whether they be 6" f/8 or short tube 80mm scopes. Some happen to be
very good performers especially considering their acquisition cost,
others are pretty bad. The consistency is lousy at that price point.
I think many would be willing to pay a fair amount more for the 6"
refractor if they could be assured that it would be an optically good
instrument with out the need for a pair of "corrective eye glasses"
for the telescope to cancel out the over-correction or the
under-correction that is quite common but not predictable from scope
to scope.
When Peter Cerravalo was testing all manner of telescopes for people
at the 1992 Texas Star Party it was appalling to hear all the reports
of 1/2 wave, 1/3 wave, rough spots, zones, etc. that he was finding in
many of the schmidt-cassegrains that he tested. A 1/4 wave or better
American made schmidt-cass was a very rare bird. If Celestron or
Meade can ever get their optics up to a 1/6 wave or 1/8 wave final
correction on a consistent basis I believe many more amateurs will
give them another try. Until then I think at least part of the appeal
of scopes from Takahashi, TeleVue, AstroPhysics, TMB and yes, even
Questar, is the assurance that you are getting a quality telescope
with optics guaranteed to perform at a testable high level.
Barry Simon
Rod Mollise
>If you reread my post what I said was that it (3" Unitron f/16) would
>compete very well with an 8" Schmidt-Cassegrain, nothing more.
>Specifically, while I did not say it in the earlier post, this was in
>regard to observations of the Moon, planets and double stars. It
HI Barry:
Being the resident Unitron expert, maybe you can clear up something for me.
I've got a Meade 4" here at USA (donated to the university a long time ago),
and I swear that mount and OTA fittings look _identical_ to what Unitron
used--to my untrained eye, anyway. One time at TSP, one of these Meades and a
Unitron were setup directly across from me. Again...I could not tell the
hardware apart. I know that John Diebel purchased the parts for these scopes
from Japan...were they not from the same company (I forget the name) that
Unitron used? BTW, at that TSP (1999) I had a chance to use both scopes rather
extensively. I thought the Unitron performed slightly better than the
Meade...but not by much.
As for the SCT vice 3" Unitron question. Yes, if you don't have time to cool
the SCT, the Unitron will emerge victorious--at this time of year, especially.
A cooled and collimated SCT? Naw. 5 extra inches of aperture is just too much
for the refractor, on the planets or anything else. The 3 and 4 inch Unitrons
(I've tried) CAN produce an _aesthetically pleasing_, beautiful image,
certainly. It's easy to forget how well a small refractor can do on the
planets. Last night I hauled my 80 f/5 out for a quick look at Saturn. Cassini
all the way around, banding on the disk--including the polar hood--and a
satellite or two besides Titan. Yes, I got a very good 80, and, yes, the seeing
was very good at times last night, but still... :-)
John McVey
My Meade SCT had a full optics replacement in 1993, and it still wasn't
that great. Our club's optical expert said he thought the star test
looked like 1/4 wave or better, but it still wasn't sweet on the planets.
Sky and Telescope published an article a few years back by an optical
guy showing that a basic rule of thumb was to subract the secondary
diameter from the primary diameter, and you'll get the equivalent
unobstructed performance. For my 8" SCT, this turned out to be about
5.5". The higher optical quality of the 5.1" refractor did the rest.
The truth is, I don't chase the faint fuzzies from dark skies in the
country that much anymore. I get more pleasure from stunning views of
the brighter objects like planets, globulars, planetaries and doubles
from my back yard.
Rather than refute the performance of a quality refractor, more folks
should experience it for themselves. It's a shame that because of high
prices, most will argue the poor economics of the APO, rather than get
a chance to delight in one.
John
Paul Schlyter
Barry Simon <bsim...@aol.com> wrote:
>"Alan French" <adfrenchre...@nycap.rr.com> wrote in message news:<qXpO9.12655$eq2.3...@twister.nyroc.rr.com>...
>> Barry,
>>
>> A very interesting and informative post, but your claim that a 3" refractor
>> will compete very well with an 8" SCT flies in the face of physics and my
>> experience. A quality 3" achromat is a fine instrument, but there is
>> nothing magical that will enable it to outdo a telescope of good quality
>> with more than twice the aperture. Even allowing for the central
>> obstruction, the jump from a 3" to an 8" scope is quite significant.
>
> Alan,
>
> If you reread my post what I said was that it (3" Unitron f/16) would
> compete very well with an 8" Schmidt-Cassegrain, nothing more.
> Specifically, while I did not say it in the earlier post, this was in
> regard to observations of the Moon, planets and double stars. It was
> not in reference to observation of faint deep sky objects.
> Even when well collimated and equalized, I have found that the typical
> 8" Schmidt-Cass cannot hold more than 40x per inch very well. Often
> the limit is closer to 30x per inch and this is with excellent
> collimation and after the scope has settled down. So a 3" refractor
> which often performs very well at 80x to 100x per inch and an 8"
> Schmidt-Cassegrain are often maxed out at very close to the same upper
> magnification. Over the 10 years that I owned an 8" Meade 2080 this
> was always disappointing to me. After I purchased a 4" Unitron back
> in 1986 and saw what clusters could really look like I lost interest
> in the Meade except for use as a piggyback guiding platform. It was
> eventually sold in 1993. As I said, I have found that a good
> achromatic refractor can often be pushed to 100x per inch. With the
> Takahashi and Brandon APO refractors that I own, I find that I can not
> only pull 100x per inch out of these scopes but I can have excellent
> color fidelity too on objects like Sirius, Venus and the limb of the
> Moon.
for 3 years. I then got to spend an evening with an 8" Celestron
SCT. Before that evening I was really excited -- TWICE MY CURRENT
APERTURE! But while at the telescope, I got VERY disappointed that
the sharpness of the image was no better at all than on my own 4"
refractor. That 8" SCT was permanently mounted, so cool-don time was
not an issue. The image wasn't "trembling" either, so the seeing
didn't appear to be particularly bad. The image was just not as
sharp as I had expected.
After that experience, I wasn't particularly eager at all in getting
an SCT telescope. So that 102 mm Polarex refractor is still my
largest instrument. Since then I have added an Astroscan (it has the
same aperture as that refractor but it yields MUCH less sharp images;
I got it to have a portable instrument which magnifies a bit more
than binoculars). I also got a pair of 20x80 binoculars, and that's
actually the instrument I use most often.
--
----------------------------------------------------------------
Paul Schlyter, Swedish Amateur Astronomer's Society (SAAF)
Grev Turegatan 40, S-114 38 Stockholm, SWEDEN
e-mail: pausch at saaf dot se
WWW: http://hem.passagen.se/pausch/index.html
http://home.tiscali.se/~pausch/
Jan Owen
city with lots of light pollution does not give the edge to smaller
aperture. You will see more detail with a properly equilibrated and
critically collimated larger scope, whether your target is lunar/planetary
detail, or deep space objects.
What MAY be a problem is not allowing sufficient time for the scope to come
to thermal equilibrium, or not getting the scope critically collimated, or
BOTH at the same time. I have found that very few folks ever get their
scopes properly collimated. Don't ask me why. It isn't difficult. They
just go through the process, after a fashion, but never really do the job
properly, pronounce the scope in perfect collimation, see soft images and
blame the scope, when the real culprit is a little closer to home... Same
with equilibration. Most folks don't allow their scopes sufficient time to
reach thermal equilibrium with the surrounding air. Until it does, the
images will be soft, and there are likely to be tube currents that will
further degrade images, especially if there is not sufficient room in the
light path between the mirror's edge and the tube wall... Depending on the
scope type, the primary mirror's thickness, and how open the rear cell and
tube assembly is to the surrounding air (note that an SCT is a closed tube,
so extra time is automatically required, and use of a fan or SCT cooler is
required if achieving equilibrium any time soon is a necessity), unaided
equilibration may take as little as half an hour to three hours or more...
Fans can be your friend...
"Getting them out there" is another thing. If the scope is a backbreaker,
it won't be used as often as one that is easy to take out, set up, and use
quickly. THAT is where the smaller refractors excel. They move easily and
quickly, they equilibrate quickly, and they are less likely to come out of
collimation. But that doesn't make them the better scope. More convenient,
yes. Quicker to get into action, yes. But not better.
Getting your SCT into action can be helped an astonishing amount through the
purchase of one of the new versions of JMI Wheeley bars with the 5" wheel
option. Those large wheels make a huge difference in ease of movement, and
will allow you to move the scope, fully assembled, all around the house,
through doors, over thresholds, off patio slabs, and around outside with
ease. Much easier, even, than JMI's original wheeley bars, which are nice,
but have much smaller wheels... If you are careful, you may not even jar it
out of collimation while moving it. Better check, though, if you want to
ensure crisp images... And better run a big fan on it from the rear for
about an hour before you plan to observe. Or use a Lymax SCT cooler...
As for your Dob, a simple hand truck and a nylon strap to secure the scope
to the hand truck makes handling and moving even large, fully assembled,
Dobs child's play. Won't make them easier to transport in a car, but will
make it easy to move them around in the house, take them outside, and move
around out there, and if you are careful, you may not even bump the scope
out of collimation (but always check)... Judicious use of fans, whether
integral to the scope, or just a fan blowing on the back of the mirror to
speed equilibration, can make that well-collimated scope really sing...
"Mike Rogers" <qv...@btinternet.com> wrote in message
news:53228764.02122...@posting.google.com...
clyde crewey
I think you're mis-understanding what Alan was saying. His point was
not that you may use a smaller scope more, rather that a 3" scope
will not out-perform an 8" one. I have a high end 85mm APO (TV) and a
low end 6" Dob. No question the APO has better optics, but it simply
can't match the Dob on some objects. Saturn is a prime example and
probably my favorite target at the moment. Globulars as well. My
refractor will split the Double Double at 60x and show gorgeous
wide-field views. Which are it's strengths of course. If I had to
have only one scope it would be the APO because I also am fond of
solar and nature viewing and it's size makes it ideal. It's really
nice to have them both though and I don't have plans to give up either
one. Your Genesis on the Telepod sounds like a wonderful compromise
between performance and portability.
Clyde
qv...@btinternet.com (Mike Rogers) wrote in message news:<53228764.02122...@posting.google.com>...
Alan French
I had a similar experience around 1976 or so. After a public Star Watch,
four of us compared an RV-6, a 4" Unitron equatorial, and an 8" Celestron.
We viewed M-13 and Jupiter. Everyone agreed that the RV-6 came in first,
followed by the 4" Unitron, and then the 8" SCT.
We have several quite recent SCTs that come regularly to our public Star
Watches. The optics seem quite reasonable, and I think comparisons made a
quarter of a century ago are no longer meaningful.
Clear skies, Alan
"Paul Schlyter" <pau...@saaf.se> wrote in message
news:aufab0$2037$1...@merope.saaf.se...
> [SNIP]
> Back in 1974 I had been the owner of a 102 mm f/15 Polarex refractor
> for 3 years. I then got to spend an evening with an 8" Celestron
> SCT. Before that evening I was really excited -- TWICE MY CURRENT
> APERTURE! But while at the telescope, I got VERY disappointed that
> the sharpness of the image was no better at all than on my own 4"
> refractor. That 8" SCT was permanently mounted, so cool-don time was
> not an issue. The image wasn't "trembling" either, so the seeing
> didn't appear to be particularly bad. The image was just not as
> sharp as I had expected.
> [SNIP]
Alan French
I am not saying that aperture is everything. In terms of what you see
through the telescope, however, it pretty much is. If you compare two
quality telescopes the aperture is going to determine what you can see. You
do have a make a little allowance for central obstruction when it comes to
low contrast details.
There certainly are other considerations. Cool down time and ease of set up
are two of them. Some folks are willing to give up some aperture to gain in
cool down and ease of use. We have people in our club who are having a ball
with modest sized refractors (an older TV Genesis, a TV 85, and three 105mm
Travelers come to mind).
My main point is that a 3" achromat of any sort is not going to compete very
well with an 8" scope unless something is seriously amiss with the 8".
Clear skies, Alan
"Mike Rogers" <qv...@btinternet.com> wrote in message
news:53228764.02122...@posting.google.com...
Alan French
Yes, Peter's testing at TSP was most interesting. Sue's notes are still
downstairs.
I agree that a big appeal of the "high end" scopes is their consistency. I
think if you look at some of the various optical test reports floating
around you will find that many of them are in the 1/6 wave PTV park. (Of
course we all know now that what is really important is the measured RMS
value for the optics.)
Clear skies, Alan
"Barry Simon" <bsim...@aol.com> wrote in message
news:989139d7.02122...@posting.google.com...
> [SNIP]
Alan French
Shhh! You suggestion is likely to result in longer waits for APOs.
Clear skies, Alan
"John McVey" <jrm...@cableone.net> wrote in message
news:3E0B29C0...@cableone.net...
> [SNIP]
Alan French
Thanks you.
A 5" unobstructed scope is certainly going to be a lot closer to an 8"
obstructed scope, although the 8" will still have the edge in terms of light
grasp and resolution of high contrast detail.
Clear skies, Alan
BTW, I am pretty sure we can make the Conjunction this year. Are you
planning to attend?
"DGM Optics" <dgmo...@erols.com> wrote in message
news:aue41l$2i0$1...@bob.news.rcn.net...
Peter Abrahams
> time ago), and I swear that mount and OTA fittings look _identical_ to
> what Unitron used
Around 1980, Meade sold a 105 / 1500, with fittings that very much resembled
Unitron hardware. This was a very high quality Japanese refractor, really
completely different than any other Meade product I've seen.
I heard, and cannot verify, that this was an attempt to test the market for
high quality refractors -- and it failed pretty dramatically.
I've only seen one of these 105s.
I imagine there are ads in S&T from that era that show the scopes.
(I'm not implying that this was the only high quality Meade product, though
from that era it probably was. I'm also not implying that Unitrons are more
than good achromats with uneven quality control, typically with very good
hardware.)
--
Peter Abrahams
The history of the telescope & the binocular:
http://www.europa.com/~telscope/binotele.htm
W. Snell
Admittedly, this is a significant problem in the case of an SCT, but
usually so much less so in a Newtonian that the effects on even low
contrast detail can be almost negligible.
The 8" SCT has about twice the light grasp of the 5" even with the
loss at each surface and due to the CO; hardly just an "edge." The
increased resolving power of the 8" is also important.
Since the SCT is a "compromise" optical system it is an easy target
for unfair comparisons. Try comparing the 5" refractor to a good 11"
or 12" SCT or large well-made Newtonian (each closer to the price of
the 5") and see how it fares.
"Alan French" <adfrenchre...@nycap.rr.com> wrote in message news:<pFMO9.139748$Vz2.33...@twister.nyroc.rr.com>...
DGM Optics
Giving the benefit of a doubt, I cited a best case scenario for the SCT
(maybe using the Meade UTHC coatings). Whether the UTHC coatings really have
96-97%RX and 98-99%TX I don`t know. This best case SCT with a 35%
obstruction really is more like about 6.8 instrument in terms of light
gathering. A worst case SCT (97%TX corrector 90%TX mirror surfaces) looks
more like a 6.3" instrument. The unobstructed 5" with say 92% optical
thruput (96% objective 96% secondary diagonal) is about like a 4.8"
instrument.
Also of interest in this long standing debate is the "Stiles Crawford
Effect". I hadn`t heard of this until it was brought to light by Roland
Christian in a recent thread {4' refractors outperform 6" CATs on DSOs
??}Also doing a web search will yield some links on the study.
http://groups.google.com/groups?dq=&hl=en&lr=&ie=UTF-8&safe=off&threadm=bc2d
008a.0207250648.5bd86ff8%40posting.google.com&rnum=1&prev=/groups%3Fq%3Dg:th
l1468118436d%26dq%3D%26hl%3Den%26lr%3D%26ie%3DUTF-8%26safe%3Doff%26selm%3Dbc
2d008a.0207250648.5bd86ff8%2540posting.google.com
Dan McShane
www.dgmoptics.com
"W. Snell" <wsne...@hotmail.com> wrote in message
news:efbad56b.0212...@posting.google.com...
DGM Optics
The Conjunction; I`ll be there. Ah, the summer time, trees with leaves, star
parties, warm weather,....sigh.
How much of the white stuff you guys get from the Christmas day storm?
C.S.
Dan
"Alan French" <adfrenchre...@nycap.rr.com> wrote in message
news:pFMO9.139748$Vz2.33...@twister.nyroc.rr.com...
Barry Simon
> Being the resident Unitron expert, maybe you can clear up something for me.
> I've got a Meade 4" here at USA (donated to the university a long time ago),
> and I swear that mount and OTA fittings look _identical_ to what Unitron
> used--to my untrained eye, anyway. One time at TSP, one of these Meades and a
> Unitron were setup directly across from me. Again...I could not tell the
> hardware apart. I know that John Diebel purchased the parts for these scopes
> from Japan...were they not from the same company (I forget the name) that
> Unitron used? BTW, at that TSP (1999) I had a chance to use both scopes rather
> extensively. I thought the Unitron performed slightly better than the
> Meade...but not by much.
The Meade 4" refractor (available in the late 70's) is truly a
different scope than the 4" Meade. The tube hardware and mount have
major differences, and these are obvious when the scopes are viewed
side by side. Comparing the two is like comparing an 8" Celestron
Schmidt-Cass to an 8" Meade Schmidt-Cass in that they are equivalent,
but they are not the same. I will let the owners of each debate which
one is better.
> As for the SCT vice 3" Unitron question. Yes, if you don't have time to cool
> the SCT, the Unitron will emerge victorious--at this time of year, especially.
Precisely the point I was making. As many have time for quick
sessions out on the driveway or in the backyard only, a small to
moderate sized refractor will often be the best choice.
> A cooled and collimated SCT? Naw. 5 extra inches of aperture is just too much
> for the refractor, on the planets or anything else.
This assumes a SCT with good optics. Unfortunately there are many out
there with less than good optics, not to mention poor collimation and
the owner who is impatient to get a quick look at something just a few
minutes after the scope is dragged out and set up. I will concede
that a great SCT with superior optics which is properly collimated and
properly equalized will eat a 3" refractor for lunch.
Barry Simon
W. Snell
twice the light grasp of the refractor. Why would a 15-25% loss of
light outweigh a 100% advantage?
As for the long thread you mentioned, I will leave it alone and simply
say that for serious deep-sky observing I would recommend something
considerably larger than a 150mm Mak or refractor. I would also make
the same recommendation for serious planetary observing. Of course
many others have already said that, but sometimes it seems to need
repeating. :)
Thanks for your reply.
"DGM Optics" <dgmo...@erols.com> wrote in message news:<augm39$33e$1...@bob.news.rcn.net>...
Barry Simon
> We have several quite recent SCTs that come regularly to our public Star
> Watches. The optics seem quite reasonable, and I think comparisons made a
> quarter of a century ago are no longer meaningful.
>
> Clear skies, Alan
Alan,
What is it different about the optics in let's say a 1977 Celestron
C-8 and a 2002 Celestron 8 beyond perhaps better coatings that make
the 2002 model better optically?
Barry Simon
DGM Optics
> Again, using your numbers, 6.8 and 4.8, the result is that the SCT has
> twice the light grasp of the refractor. Why would a 15-25% loss of
> light outweigh a 100% advantage?
I would submit that doubling the light gathering power does not equal a 100%
advantage. Especially if the instrument with the *100%* advantage has a
limited actual FOV, significantly greater scattering, and lower contrast. I
know the new generation of SCT`s are markedly superior to the same of a few
years ago, I just continue to be underwhelmed by the views I have seen with
them. (Don`t like the focusing mechanism/method at all. Can never really
"nail" the focal point.)
> As for the long thread you mentioned, I will leave it alone and simply
> say that for serious deep-sky observing I would recommend something
> considerably larger than a 150mm Mak or refractor. I would also make
> the same recommendation for serious planetary observing. Of course
> many others have already said that, but sometimes it seems to need
> repeating. :)
Well, yes. At Stellafane a few years ago I thought the view of NGC 7331 thru
a 32" dob looked more like the view of M31 thru a 4-5 inch scope, but what
has also been stated by some, on this and other threads, is that bigger is
not always better for a variety of reasons.
It`s the never ending debate that can best be summed up with "different
scopes for different folks".
Thank you also!
Clear Skies
Rod Mollise
>C-8 and a 2002 Celestron 8 beyond perhaps better coatings that make
>the 2002 model better optically?
>
>
Hi Barry:
Far better consistency.
Better correction, usually, than the best of the old ones.
The coatings make a noticeable difference--I can tell the difference easily
between the 1995 Ultima 8 with Starbright here and the '73 Orange Tube.
Rod Mollise
>The Meade 4" refractor (available in the late 70's) is truly a
>different scope than the 4" Meade. The tube hardware and mount have
>major differences, and these are obvious when the scopes are viewed
>side by side.
Hi Barry:
I'm a little dense this morning. Are you saying the hardware on the 70s Meade
we have here is indeed the same as on the Unitrons?
One interesting feature of this scope, which I think some Unitrons may have
shared too, is that the big wooden tripod's legs _fold_ up.
Quite a few SCTs are not collimated. I'm working to change that. Optically,
though, quite frankly it's rare to find a bad one these days. The Bad Old Days
for SCTs? 1986 - 1990. Halley Time. Prior to that, both Meade and Celestron
turned out some good ones. Some very good ones. But some D-O-G-S too. They are
much more consistent now. To both companies' credit, they really did clean up
their optical act in the late 80s - early 1990s. Any late 80s SCT of any model
of any manufacturer is suspect, however.
Alan French
up to 36". The driveway and bird feeders are dug out. Still have to dig
out for telescopes.
Clear skies, Alan
"DGM Optics" <dgmo...@erols.com> wrote in message
news:augmfu$44d$1...@bob.news.rcn.net...
Alan French
My impression is that the overall optical quality is better. They seem to
be doing a much better job figuring them and they seem to be more
consistant.
Clear skies, Alan
"Barry Simon" <bsim...@aol.com> wrote in message
news:989139d7.02122...@posting.google.com...
>
Chris1011
Better correction, usually, than the best of the old ones.>>
Spherical correction is only one attribute of a good mirror. I'll bet that the
surface roughness is still the same as the old SCTs. Try comparing one of the
new SCTs to a Zambuto mirror with a knife edge test and see what the surface
quality difference might be.
Good spherical correction will get you similar inside/outside Fresnel rings in
the out-of-focus star test, but good surface smoothness is the main criteria
for high planetary contrast. I doubt that modern SCT manufacture using high
speed equipment has improved on the old tried and true low speed pitch process
when it comes to surface smoothness.
Roland Christen
DGM Optics
Funny little O.T. local story;
A Worcester electronics store had a 3 day after Thankingsgiving sales promo
where they would give a full refund to all merchandise purchased within a 5
hour window each day, *IF* Worcester regional airport recorded 6+ snow on
Christmas day.
Oops, 13.5" fell! The kicker is that they took out insurance on the deal
(What would you call that? Sales Promotion Gambling Insurance?).
Statistically it would seem to have been a good bet though as the previous
record was a mere 5.8"
Dan
"Alan French" <adfrenchre...@nycap.rr.com> wrote in message
news:4U_O9.23648$eq2.5...@twister.nyroc.rr.com...
Mirabulous
sort of scope that on some nights, the atmosphere will be such that an 8" may
show no more detail than a 3".. bad seeing is a common limiter of both
resolution and magnification regardless of size, optical quality, collimation,
or thermal equilibrium. This can be a contributing factor in how a smaller
scope can often be pushed to higher "per inch" magnifications, too, with
respect to a larger scope. If an 8" and a 3" top out at 200x on a given night,
it may not be due to quality differences between them. But the person with the
3" can say "well, mine was up to 66x per inch, yours only made it to 25x per
inch so my scope just blows your away optically". Misleading, at best. So,
basically, a quick comparison on a single or even a couple of nights, doesn't
necessarily tell you much at all about optical quality differences. To really
ascertain the differences in quality, tests under controlled conditions or
long-term use of the scopes under real-world conditions would be necessary.
Without that, it's really just boasting.
Amy
Barry Simon
> >
> >The Meade 4" refractor (available in the late 70's) is truly a
> >different scope than the 4" Meade. The tube hardware and mount have
> >major differences, and these are obvious when the scopes are viewed
> >side by side.
>
> Hi Barry:
>
> I'm a little dense this morning. Are you saying the hardware on the 70s Meade
> we have here is indeed the same as on the Unitrons?
Oops! Typo on my part, the second "Meade" should have read ..."than
the 4" Unitron."
> One interesting feature of this scope, which I think some Unitrons may have
> shared too, is that the big wooden tripod's legs _fold_ up.
On the 4" Unitron the legs neither retracted or folded so there was no
height adjustment, but they were less prone to be a "weak link" this
way. The 3" and 2.4" Unitrons did have legs that folded in and up for
transport. They too were not adjustable. Earlier 2.4" Unitrons did
have legs which retracted. With their sharply pointed black painted
metal ground spikes, Unitron legs look like giant pencils.
Barry Simon
Siegfried Gonzi
> Even when well collimated and equalized, I have found that the typical
> 8" Schmidt-Cass cannot hold more than 40x per inch very well. Often
> the limit is closer to 30x per inch and this is with excellent
> collimation and after the scope has settled down. So a 3" refractor
> which often performs very well at 80x to 100x per inch and an 8"
> Schmidt-Cassegrain are often maxed out at very close to the same upper
> magnification.
[Please: do not become offenden and insulted but sometimes I cannot resist]
I use exclusively my bicycle, because most of the time a car driver is
caught in a jam.
The refractor fever strikes back again.
In the meantime: Pepsi and a desert (instead of Coca Cola and a desert).
It is time again for me to cease and desist for a few month, because I
went sour of all this: Refractor fewer has wreaked havoc in my brain and
my dead brain seeks desperately explanations why my small finder scope
can stack up against the well known 8" SC; I cannot sleep any longer: I
need any explanations why my overprized device is not overprized and
overhyped yet.
Wasn't the waiting time of 5 years not long enough? Or did you pray
every free minute: please God do not make my Astrophysics entry void.
If you find a person drunken in a desert: that is me.
S. Gonzi
Alan French
commercial mirror. There was never a night when the 60mm came close to the
8" in terms of planetary detail.
We now have scopes from 92mm to 14.5" aperture, and often have two scopes in
the 92mm to 10" range out at the same time. I have not yet seen a night
when there were not moments to minutes when the larger scope would reveal
more detail than the smaller, and on many nights the larger simply does
better all the time. I think that folks are making a mistake when the
select a 3" to 4" scope with the idea that it will show all that can be seen
because of seeing limitations. (There are other issues that may the smaller
a better choice for some folks.)
Clear skies, Alan
"Mirabulous" <mirab...@aol.com> wrote in message
news:20021227153655...@mb-mg.aol.com...
> We can't forget that with regards to comparisons of different apertures of
any
> sort of scope that on some nights, the atmosphere will be such that an 8"
may
> show no more detail than a 3".. bad seeing is a common limiter of both
> resolution and magnification regardless of size, optical quality,
collimation,
> or thermal equilibrium. [SNIP]
Barry Simon
> My first scopes was a 60mm Unitron. I then made an 8" Newtonian with a
> commercial mirror. There was never a night when the 60mm came close to the
> 8" in terms of planetary detail.
Alan,
I think you will agree that part of the appeal of any telescope is the
joy in simply using it. Sometimes the appreciation for a telescope, a
car, a favorite fishing rod or shotgun goes beyond the qualities
intrinsic to the particular item. I guess I am talking about
nostalgia. Many amateur astronomers of my vintage (I am 50) and a bit
older, were bombarded for years by the Unitron, Questar, Cave and
Criterion ads in SKY & TELESCOPE. Now that we can afford these scopes
or have many years of cherished memories using these scopes it does
not really matter if something a bit more sophisticated can do
something a tiny bit better.
I had a Triumph TR6, by today's standards it is considered a dinosaur,
but it sure was a lot of fun to drive. If my old Triumph and a brand
new Mazda Miata suddenly materialized in my driveway, the Triumph
would be the one I would want to take out for a country drive.
When it comes to using a telescope at night, for me, there is just
something about using a classical refractor that pushes it past other
telescopes that may have greater aperture or more sophistication. I
am not out discovering supernova or cataloging and recording my
observations of faint variable stars, I am just out to have a good
time under the night sky. For me a refractor is the best vehicle for
helping me achieve that goal.
Barry Simon
Alan French
Folks should use whatever scope they enjoy. I understand what you say about
nostalgia, and I am of that era. I bought the 60mm Unitron because I had
seen the ads gracing the back cover of S&T for years. (If I had known a
little more, however, I probably would have gotten an RV-6.) I guess I am
somewhat ambivalent about telescope nostalgia. My 60mm Unitron went to the
Stellfane swap table several years ago. I did own a Questar for several
years, but it is also no longer here. I picked up a very nice RV-6 a while
ago and it still resides downstairs, but will probably not be here much
longer. We can only house and use so many scopes.
Clear skies and happy holidays, Alan
"Barry Simon" <bsim...@aol.com> wrote in message
news:989139d7.02122...@posting.google.com...
> "Alan French" <adfrenchre...@nycap.rr.com> wrote in message
news:<y06P9.148051$Vz2.35...@twister.nyroc.rr.com>...
> > My first scopes was a 60mm Unitron. I then made an 8" Newtonian with a
> > commercial mirror. There was never a night when the 60mm came close to
the
> > 8" in terms of planetary detail.
>
> I think you will agree that part of the appeal of any telescope is the
> joy in simply using it. Sometimes the appreciation for a telescope, a
> car, a favorite fishing rod or shotgun goes beyond the qualities
> intrinsic to the particular item. I guess I am talking about
> nostalgia. Many amateur astronomers of my vintage (I am 50) and a bit
> older, were bombarded for years by the Unitron, Questar, Cave and
> Criterion ads in SKY & TELESCOPE. Now that we can afford these scopes
> or have many years of cherished memories using these scopes it does
> not really matter if something a bit more sophisticated can do
> something a tiny bit better.
> [SNIP]
Rod Mollise
>somewhat ambivalent about telescope nostalgia.
HI Alan:
Me too. It's wonderful in theory...but...:-)
I still remember the first really premium scope I was able to buy...in '75...a
Cave 8. Man how I'd dreamed about it for 10 years...from the time I saw that
first ad in Sky and Telescope! However, after using it for a few months
(particularly, one cold Winter when I wrestled it into my compact car and into
the Ozark Mountains numerous times, I was quite glad to sell it for the much
more practical and user friendly (for me) but less "legendary" C8! ;-)
Richard P. Johnson
Rod Mollise wrote:
>
> I still remember the first really premium scope I was able to buy...in '75...a
> Cave 8. Man how I'd dreamed about it for 10 years...from the time I saw that
> first ad in Sky and Telescope! However, after using it for a few months
> (particularly, one cold Winter when I wrestled it into my compact car and into
> the Ozark Mountains numerous times, I was quite glad to sell it for the much
> more practical and user friendly (for me) but less "legendary" C8! ;-)
>
Gee, then you wouldn't have liked to wrestle my '62 vintage 10" f/8 Cave Astrola
into your car. You didn't say what f ratio that 8 was but even 80" vs 64" plus
the bigger mount is BIG difference. Nearly 50 years later and I'm still doing
it! That's why I still have a 70's vintage station wagon, only vehicle short of a
semi that can carry it. The finder is a 10 x 40mm Unitron. The only Unitron I
ever owned. The Cave is a superb planetary scope.
Rick
Rod Mollise
>Astrola
Hi Rick:
I can still recall how cold it was at 4am, whimpering when it came time to pack
up. :-)
D Stoke
I saw a high end Meade refractor in 1977 issue of Sky and Telescope.
Douglas
Rod Mollise
>I saw a high end Meade refractor in 1977 issue of Sky and Telescope.
Hi:
I believe they are long since out of business.
CHASLX200
>From: "Richard P. Johnson" wa0...@inetnebr.com
>Date: 12/28/02 5:24 PM Eastern Standard Time
>Message-id: <3E0E24DD...@inetnebr.com>
>
>
>Gee, then you wouldn't have liked to wrestle my '62 vintage 10" f/8 Cave
>Astrola
>into your car. You didn't say what f ratio that 8 was but even 80" vs 64"
>plus
>the bigger mount is BIG difference. Nearly 50 years later and I'm still
>doing
>it! That's why I still have a 70's vintage station wagon, only vehicle short
>of a
>semi that can carry it. The finder is a 10 x 40mm Unitron. The only Unitron
>I
>ever owned. The Cave is a superb planetary scope.
>
>Rick
*******************
You should try to wrestle a 14.5" F7.5 Newt, that weighed 140lbs out the back
door! Thank god the mount stayed out side, it weighed 450lbs...
Chas P.
Richard P. Johnson
CHASLX200 wrote:
> You should try to wrestle a 14.5" F7.5 Newt, that weighed 140lbs out the back
> door! Thank god the mount stayed out side, it weighed 450lbs...
>
> Chas P.
You win! We have one member with a 30" obsession he hauls fully assembled in a
huge trailer. I'm too old for this any more. The 10" sits in the garage with
heavy duty double castors I found someplace. I just roll it out crank down the
pads that lift it off the castors and start viewing. Have the driveway marked
where those pads go so it is in good polar alignment when the pads hit the mark.
Cuts down the hassle part. But when it comes to taking it to a star party then my
back says it is too old. I'll still climb a 10' ladder to look in that 30"
however.
Rick
CHASLX200
>Message-id: <3E0F7E76...@inetnebr.com>
>
>You win! We have one member with a 30" obsession he hauls fully assembled in
>a
>huge trailer. I'm too old for this any more. The 10" sits in the garage
>with
>heavy duty double castors I found someplace. I just roll it out crank down
>the
>pads that lift it off the castors and start viewing. Have the driveway
>marked
>where those pads go so it is in good polar alignment when the pads hit the
>mark.
>Cuts down the hassle part. But when it comes to taking it to a star party
>then my
>back says it is too old. I'll still climb a 10' ladder to look in that 30"
>however.
>
>Rick
*******************
My big Newt days are over! My back can't take it.
I would love to buy the new Meade 14" LX-200, but if it wont break down, then
i can forget that!
There is no way i am gonna lift a 120lb scope...
Chas P.
jerry warner
good. I think your assessment of the schmidt-cass's is accurate
as well and well-said. I was pouring through my old Unitron catalogs and could find no f/7 (f/6.7) and was about to post this
but then found your post. Im glad I read before posting.
I think newtonians filled the needs of one era, so to speak, and
schmidt-cass's have filled a similar need to the present, while during this period thanks to people like Roland C. the
refractor
has come into its own and maks have made a stunning statement. Compared to where things were in 1940, that's some distance to
have travelled for the average person wanting to participate in astronomy.
I have no idea what the next 50 years will produce. Thanks for your illuminating posts -
-Jerry
Barry Simon wrote:
> "Alan French" <adfrenchre...@nycap.rr.com> wrote in message news:<IsvO9.14068$eq2.3...@twister.nyroc.rr.com>...
> > Barry,
>
> > From your description it seems your Meade SCT dates prior to 1986. In that
> > era I would not and did not recommend SCTs. They have come a long way since
> > then.
>
> Alan,
>
> My 2080 was one of the early ones. It was purchased in July, 1982.
> Yes, I have seen some outstanding optics on some Schmidt-Cass scopes.
> A friend has a 8" Celestron dating from the late 70's/early 80's which
> is the best I have ever seen. If I could be assured that I could get
> an optical tube assembly of that quality I would snatch it up in a
> second.
>
> This leads us to the whole question of quality control and consistency
> in any optical layout we may consider. It has often been said that
> the Schmidt-Cassegrain is a great idea, but when executed for the
> masses at a price point that the typical consumer is willing to pay,
> some shortcuts are taken. Takahashi made a schmidt-cass about a
> decade ago, the TSC 225; for tube assembly alone it was close to
> $4000, the price you pay for a very well executed and virtually
> optically perfect design. More importantly it was consistently
> excellent. Unfortunately at it's price point not many have been able
> to see what a truly excellent schmidt-cassegrain is able to do, only
> 100 were made.
>
> Same thing applies to the current invasion of Chinese made refractors
> whether they be 6" f/8 or short tube 80mm scopes. Some happen to be
> very good performers especially considering their acquisition cost,
> others are pretty bad. The consistency is lousy at that price point.
> I think many would be willing to pay a fair amount more for the 6"
> refractor if they could be assured that it would be an optically good
> instrument with out the need for a pair of "corrective eye glasses"
> for the telescope to cancel out the over-correction or the
> under-correction that is quite common but not predictable from scope
> to scope.
>
> When Peter Cerravalo was testing all manner of telescopes for people
> at the 1992 Texas Star Party it was appalling to hear all the reports
> of 1/2 wave, 1/3 wave, rough spots, zones, etc. that he was finding in
> many of the schmidt-cassegrains that he tested. A 1/4 wave or better
> American made schmidt-cass was a very rare bird. If Celestron or
> Meade can ever get their optics up to a 1/6 wave or 1/8 wave final
> correction on a consistent basis I believe many more amateurs will
> give them another try. Until then I think at least part of the appeal
> of scopes from Takahashi, TeleVue, AstroPhysics, TMB and yes, even
> Questar, is the assurance that you are getting a quality telescope
> with optics guaranteed to perform at a testable high level.
>
> Barry Simon
jerry warner
a man who has never lived. I kept all of my rollout Cave mounts.
Sure they only track for visual but that's what I want and they have worked reliably
for 40+ years. No muss - no fuss - and
lots of pinpoint "noteworthy" views.
-Jerry
Richard P. Johnson
> A man without a good larger newtonian with good optics is
> a man who has never lived. I kept all of my rollout Cave mounts.
> Sure they only track for visual but that's what I want and they have worked reliably
> for 40+ years. No muss - no fuss - and
> lots of pinpoint "noteworthy" views.
> -Jerry
>
I replaced the drive in my 10" mount with a Byer's drive so it now has excellent
tracking as well as optics. The periodic error in the drives of that era was simply
amazing!
Rick
http://www.hydeobservatory.info/
http://www.prairieastronomyclub.org/
W. Snell
need a wide field of view, you should use a telescope with a short
focal length and long focal length eyepieces with large apparent
fields of view.
As for the actual performance of a "newer" SCT please refer to the
November 1997 issue of Sky and Telescope, for an interesting, although
short, comparison of an SCT and a 5-inch APO used in viewing Mars (low
contrast detail.) The SCT wins.
As for comparing a 32-inch Dob with a 5-inch telescope, of course the
32-inch wins. So would a 15-inch and apparently very often even a
relatively cheap 8-inch. Limitations in finances, storage and
schedule mean that many must settle for smaller telescopes. However,
as good as the 5-inch refractor might be, the money needed to purchase
it could easily buy a small portable telescope, a good example of an
SCT and a larger Dobsonian that together will cover most observing
situations.
"DGM Optics" <dgmo...@erols.com> wrote in message news:<auhpae$cdi$1...@bob.news.rcn.net>...