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Javier
sage
Reged: 05/03/09
Posts: 434
Loc: New Jersey
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I've narrowed down my choice of CATS to either a Celestron C8-A or a C9.25-A. In a CAT does 1.25 inches of extra aperture make that much of a difference? I'm just wondering if the extra 1.25" is worth the extra 400.00 bucks.
Thanks
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mcoren
Pooh-Bah
Reged: 01/11/06
Posts: 1176
Loc: Northern Virginia, USA
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I owned a C9.25 for about 1-1/2 years, and I really enjoyed the scope. Both scopes have loyal followings. In terms of additional light grasp, the extra 1.25" equates to about 1/3 more area. I never did a side-by-side comparison with a C8 so I don't know how much of a difference it makes (you need 2.5x area to get one more magnitude).
I think one of the things about the C9.25 is that, because it uses a slightly different optical formula than the other Celestron SCTs (longer focal ratio primary), it provides a flatter field. That's important if you're going to be doing imaging, not so much for visual.
The other thing to consider is that although the C9.25 is only 1.25" more in aperture, the OTA weight goes from 12.5 lbs to 20 lbs. Aside from the different diameter, the C9.25 has a disproportionately longer tube, about the same length as a C11. As a result, you will need a beefier mount to get good steady views, particularly if you want to do imaging.
I used an Orion SkyView Pro with mine and it was fine at moderate powers for DSO viewing, but was definitely pushing it for high-powers (a lot of shaking at 470x). I didn't use it for photography.
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Mike
Orion SkyQuest XT10
Suburban Washington DC
Edited by mcoren (11/01/09 10:17 PM)
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stevew
Pooh-Bah
Reged: 03/03/06
Posts: 1148
Loc: Vancouver
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I recently sold a C9.25.
I owned it for 4 years. Many people may tell you that there is not much differece. However I had it next to a few C8's over the years, and although the C9.25 is not in another league as far as targets go, there is a difference.
Is the small difference worth an extra $400?
I suppose that's up to you.........
Steve
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TV Genesis SDF
Meade 127ED
Antares 152
Celestron C5
Celestron C8
Celestron C11
Coulter Odyssey 8
16 Dobsonian
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LarsZ
super member
Reged: 01/12/08
Posts: 115
Loc: Sweden
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I had both a C8 and a C9.25 for a few months. As already has been said, the C8 is shorter and much lighter than the 9.25. However, when imaging, the C8 showed a lot more coma to the edges than the C9.25 when I used the Celestron 0.63 FR/FF (I didn't test without the FR/FF). The views on-axis were the same as far as I could see.
If I only would use the scope for visual, I would have kept the C8. When doing visual, I don't care about coma I try to keep the object in the center anyway.
It is probably one of the best grab-and-go scope there is concerning weight and light grasp.
However, since I spend more time with imaging than visual, I sold the C8 and kept the C9.25.
/Lars
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Rebel XSi, IDAS LPS, CGE 9.25, Orion SSAG, Starblast 4.5
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pogobbler
member
Reged: 09/30/08
Posts: 31
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I had an 8" in the past and got a 9.25" to replace it. It's a mixed bag, I think. The 9.25" will be, I found, a noticeable difference, but not a particularly large difference, as far as light gathering issues. Planetary, again, I'd give a slight nod to the 9.25", though if it was an optically mediocre 9.25" against a very good 8", I'd bet on the 8". The difference is there, to my eyes, but not huge by any means. To me, the larger difference is in the size and weight of the scope, with the 9.25" feeling considerably more hefty-- though still very manageable-- as compared to the 8". I, personally, like the handle on the mirror end of the 9.25" and like the metal end cap. That said, the 8", compared to the 9.25", feels very lightweight and will tax a mount considerably less, though both worked fine for me on a CG5 (with an improved tripod than the original) and my current ASGT mount. Another consideration, depending on what accessories you have or might eventually want, the Celestron 8" SCT has more backfocus than the 9.25" SCT, which will most likely only be important if you try to use a .63x reducer/corrector with a 2" visual back and 2" eyepiece or use a binoviewer with a reducer. I know the latter can be done, but with more trouble than if you had just a touch more backfocus. Just another consideration for you.
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Bob Griffiths
Postmaster
Reged: 10/10/05
Posts: 6592
Loc: Frederick Maryland
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Get the 9.25 IF you do not already own an 8"....
BUT if you have an 8" do not upgrade to the 9.25...
Seriously when I upgraded my 8" scope the 9.25 just was not enough improvement to be worth the expense (close to $2000 for an extra 1.25 inches)
so I passed over it and purchased a 11" ...the price per inch was just more affordable..and the visual difference was apparent wheras the difference in the 9.25 was not "exciting" in my opinion...
Bob G.
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CPC1100
Nexstar 8i + GPS & Rays Brackets
Denk S1 power switch
Orion 100 mm Refractor
Meade LXD 55 ...AR-5 127 mm Refractor
Exploradome Observatory S.I.E. (Smiling Irish Eyes)
Gerbring Heated Motorcycle clothing in the winter
39*21'03" N
77*28'12" W
The sky over my head....
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watcher
sage
Reged: 11/21/07
Posts: 406
Loc: NJ
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It really depends on your mount, and your portabilty requirements. If it were me, I'd get the 8". The 9.25 is bigger and heavier enough, that I would skip to the 11" if I had a mount that could handle it. If your mount can't handle an 11", then you're probably going to be better off with an 8" on that mount anyway.
Joe
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(quote)"That does it! Next Big Bang, someone has got to rethink this gettin' old business!" Joe Daugert
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1986 Celestron c-8 (retired)
Celestron Omni XLT 120
Celestron Astromaster 70 AZ
Vixen GP2 mount on Omni XLT tripod (soon to be driven by iOptron GOTO Nova)
Meade 16x50 binoculars
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bluedandelion
super member
Reged: 08/17/07
Posts: 197
Loc: Auburn, WA, U.S.A
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I went from a Meade LX10 fork mount to a C9.25 on an Atlas GEM. Never had a C8. Visually I found the images in the 9.25 to be brighter have more contrast (didn't do a side by side comparison so that could be the brain playing a trick). Love it for imaging. On an Atlas with a guidescope, DSLR, guide camera etc., I am probably pushing the limits, but very satisfied with the results.
I agree with what's been said here. A couple of useful links:
CN Reviews - C9.25 a good scope...
Uncle Rod has something to say here.
Scroll down to SCT Mythology at Unle ROds blog at this link
That's my bias based on my limited experience.
- Ajay
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Ajay Narayanan
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dscarpa
sage
Reged: 03/15/08
Posts: 257
Loc: San Diego Ca.
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I had to get a Lumicon shorty visual back to reach focus with my Nagler 22 and Ethos 13 when useing a reducer with my C 9.25. Much as I like my C 9.25 I find myself useing my IM 715 mak more. The IM on the WO EZ is about 2/3 of the weight of the C 9.25 on the Giro. David
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Erik Bakker
professor emeritus
Reged: 08/10/06
Posts: 534
Loc: Haren, The Netherlands, Europe
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Quote:
I've narrowed down my choice of CATS to either a Celestron C8-A or a C9.25-A. In a CAT does 1.25 inches of extra aperture make that much of a difference? I'm just wondering if the extra 1.25" is worth the extra 400.00 bucks.
Thanks
I don't think the 1.25" is too big of a deal. The difference in weight is. Pleae note that the sample-sample differences in optics can have perhaps a bigger impact on what you see and how In)sensitve your scope is to seeing conditions.
Personally, I have a weak spot for the C11 on a forkmount.
Good luck in choosing.
CS,
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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sang33ta
scholastic sledgehammer
Reged: 07/08/08
Posts: 767
Loc: UK
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extra weight is a hassel, too much focal length is a hassel.
8" f/10 fl=2000 seems to be the sweet spot IMHO 
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Hioptic 152mm f12.5 Maksutov, CG5-AGT, Meade Super Plossl Set, Casio QV-2900UX
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