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Brian L
super member
Reged: 11/17/08
Posts: 119
Loc: The garden paradise of Pittsbu...
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I thought I'd just throw this out there:
Despite conventional wisdom that fast focal lengths don't do as well on planetary targets, I can always make out more detail on the disk of Jupiter and rings of Saturn using my 110 mm f/6.5 APO refractor than my 10" f/10 SCT at roughly the same magnification. I think that other factors like tube currents, imprecise collimation, etc. mitigate the advantages of the long focal length and larger aperture. Clearly the diffraction limit of the 10" SCT should be capable of resolving more detail than the 110 mm refractor. But, even side by side I've never found that to be the case.
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WO FLT-110 f/6.5, TEC optics
Losmandy G-11 Gemini
Meade 10" LX200 GPS/UHTC
Questar 3.5" Standard
Vixen VMC-110L
Canon 450D, unmodified
Assortment of TV Panoptic, TV Radian, Vixen LVW, and WO eyepieces
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 2297
Loc: Florida
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I had similar results with my original C8 f10 purchased in the 70's. My 6 inch RV6 f8 was more contrasty and sharper by an obvious margin showing better planetary detail. Theoretically this should not be true. So it begs the question, Why? My guess is poor quality control on the C8.
Bill
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
Tasco 10K 80mm/1200mm
Towa 339 Restored
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actionhac
professor emeritus
Reged: 08/09/08
Posts: 732
Loc: WA
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I had just about thrown in the towel on SCT's when one night when everything was just perfect (for the SCT), I could not believe my eyes. My LX200EMC 10" 2500mmfl showed me why these things cost so much.
It was mind blowing. Then I started getting silly and put in my shortest fl ep on Jupiter. At 658X I could still make out bands and the planet was gigantic.
I have not been able to repeat this performance but I know what the scope is capable of.
If this was my only scope I would make a point of finding out exactly what this thing needs to perform properly. I think is black majik mon.
Robert
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Brian L
super member
Reged: 11/17/08
Posts: 119
Loc: The garden paradise of Pittsbu...
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I too have had one or two of those zen experiences with my SCT, where the right combination of ambient temperature, humidity, and air turbulence yielded uncharacteristically sharp (but ephemeral) views. I've never figured out the secret formula...probably because its far easier to roll out the refractor and start observing in a few minutes.
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WO FLT-110 f/6.5, TEC optics
Losmandy G-11 Gemini
Meade 10" LX200 GPS/UHTC
Questar 3.5" Standard
Vixen VMC-110L
Canon 450D, unmodified
Assortment of TV Panoptic, TV Radian, Vixen LVW, and WO eyepieces
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rmollise
Post Laureate
Reged: 07/06/07
Posts: 4573
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Quote:
I had just about thrown in the towel on SCT's when one night when everything was just perfect (for the SCT), I could not believe my eyes. My LX200EMC 10" 2500mmfl showed me why these things cost so much.
Robert
"Cost so much"?! SCTs are dirt cheap and have been for a while considering what ya get. That's been one of Meade's and Celestron's ongoing problems. 
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Uncle Rod
Rod's New Book:
Choosing and Using a New CAT
Available now!
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Brian L
super member
Reged: 11/17/08
Posts: 119
Loc: The garden paradise of Pittsbu...
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If companies like AstroTech have figured out how to make 8-10" RC optics with quartz primaries for less than $1,500, it could be the beginning of the end for the SCT. I've been seriously considering hanging up my SCT for one of those AT8RC's.
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WO FLT-110 f/6.5, TEC optics
Losmandy G-11 Gemini
Meade 10" LX200 GPS/UHTC
Questar 3.5" Standard
Vixen VMC-110L
Canon 450D, unmodified
Assortment of TV Panoptic, TV Radian, Vixen LVW, and WO eyepieces
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Clive Gibbons
Mostly Harmless
Reged: 05/26/05
Posts: 13439
Loc: Oort Cloud
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Quote:
Okay... I pulled the trigger and bought one. It's a '67 standard model with the older Erfle eyepieces. Not sure whether or not the eyepiece barrel is compatible with the later Brandon design-- I seem to remember that the barrel is wider with these scopes. I guess I'll find out. It will be interesting to see how it stacks up against my TEC 110 on the targets that the Questar excels at.
Hi Brian.
Congrats on your vintage Q purchase. 
The "40x" ocular is a 3 element Konig design and the "80x" ocular is a 5 element Erfle.
To use the later Questar Brandon eyepieces in your scope, you'll need a different adapter.
Hope the ol' Q works out well for you.
My '62 vintage model is still chugging along and provides excellent views.
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A few telescopes of dubious value.
Understanding wife, two curious cats and one sadly departed.
"Semper ubi sub ubi"
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gschnelk
member
Reged: 12/11/08
Posts: 16
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To All
I bought a Questar several years ago. I could go on for hours (as we all can) but allow me to say this: I really wanted a small aperture refractor but could not find a mount that met my criteria of very light weight with the functions I required. I did not want a scope that would just sit and look pretty and that's what would have happened if I acquired an
excellent tube with something like a GM-8 mount. I would say "Maybe tomorrow night." I have a bad back so cannot lift 30 to 80 pounds without several weeks of pain. If I have to disassemble - same response. So... I bought a Questar. A final note: The Questar ia delightful in many respects and disappointing to me in a few respects.
Gary
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Erik Bakker
professor emeritus
Reged: 08/10/06
Posts: 532
Loc: Haren, The Netherlands, Europe
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Quote:
I thought I'd just throw this out there:
Despite conventional wisdom that fast focal lengths don't do as well on planetary targets, I can always make out more detail on the disk of Jupiter and rings of Saturn using my 110 mm f/6.5 APO refractor than my 10" f/10 SCT at roughly the same magnification. I think that other factors like tube currents, imprecise collimation, etc. mitigate the advantages of the long focal length and larger aperture. Clearly the diffraction limit of the 10" SCT should be capable of resolving more detail than the 110 mm refractor. But, even side by side I've never found that to be the case.
That 10" of yours must have not-so-good optics. My Q7 dwarfs my Astro-Physics 130mm f/6 on everything except widefields.
Clear skies,
Erik
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Visual astronomer, main instruments:
Fully mounted Questar 7 P-BB
Celestron C 102F f/8.8 fluorite
Vixen FL 70S f/8 fluorite
Celestron C 55F f/8 fluorite
Sets of Zeiss, TeleVue and Brandon eyepieces
Zeiss 7x50 Marine B/GA
Zeiss TM german equatorial
Gitzo 224 with Manfrotto 501 fluid head
Unitron alt-az mount
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Brian L
super member
Reged: 11/17/08
Posts: 119
Loc: The garden paradise of Pittsbu...
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Erik-
That's what I thought, but I did a lot of star testing with an artificial star and there were not any obvious optical defects. Collimation is good.
I am not saying that the 10" is bad- I've looked through other people's SCT's and the high magnification views aren't any better. I think the limiting factors for both scopes under usual observing conditions here in W. PA are atmospheric. It's just that the 4" TEC optics seem to perform better under those conditions.
--------------------
WO FLT-110 f/6.5, TEC optics
Losmandy G-11 Gemini
Meade 10" LX200 GPS/UHTC
Questar 3.5" Standard
Vixen VMC-110L
Canon 450D, unmodified
Assortment of TV Panoptic, TV Radian, Vixen LVW, and WO eyepieces
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