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ryanr256
member
Reged: 04/21/09
Posts: 30
Loc: Southwest Ohio
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Before I plunk down the funds for the Meade 3.3 Focal Reducer I would like some reassurance that it will work (be focusable) with my C8 and DSI Pro II.
Is anyone currently using, or has anyone in the past used, this combo for their imaging? I am planning on attaching the FR directly to the C8 and then attaching the DSI to the FR. No diagonal or other item in the optical path, except for the variable adapter that comes with the 3.3 FR.
Thanks,
-Bob
Edited by ryanr256 (11/03/09 08:09 PM)
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jgraham
Postmaster
Reged: 12/02/04
Posts: 6764
Loc: Dayton, Ohio
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I've used an f/3.3 focal reducer on my LXD75 SC8 and my old DSI Pro without any problems. If I recall right the best results were with the camera attached directly to the focal reducer or with a very short extension tube (from ScopeStuff). I made a simple step-down ring to hold the IR pre-filter just in front of the filter slide.
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-John
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Homebuilt scopes from 4.25-16.5"
Meade LXD75-N6/SN6/SC8, DSX-90, ETX-60BB, ETX-125PE, DS-2130
Orion StarBlast, BinoViewers, Coronado PST
Rebel XT/XTi, DSI Pro (I, II, & III), DSI, LPI, Electronic Eyepiece, Phillips SPC900NC
Tasco 60mm Refractors
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antimorris
sage
Reged: 08/16/09
Posts: 245
Loc: San Antonio-ish, TX
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I just attempted this . . . and just sold my 3.3 FR . . . It is doable if you use the DSI with its built in filter slide, but I have a filter wheel attached so the CCD was too far and therefore had alot of coma, even with no tube and just an adapter to adjust the threads. If you have something like I did (the filter wheel), I wouldnt recommend it, otherwise, it is doable.
edit: I did try it by reinstalling the original filter slide and I did not get the coma with that setup but I didnt want to change the filter set up everytime I wanted to use it. Either way it was focusable - just got the coma with it on the filter wheel
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Anna
CPC 800 XLT w/FeatherTouch micro-focuser
Orion EON 80ED
unmodded Nikon D40
Meade DSI II Pro with ATIK Filter Wheel & Outback Razorback Cooler
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Morris Astronomy
My Astro Blog
"sic itur ad astra"
Edited by antimorris (11/03/09 10:30 PM)
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AlanT
sage
Reged: 08/20/07
Posts: 488
Loc: 122º36' W, 47º37' N, WA USA
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I don't have a C-8, but I have used the 3.3 on my C-6. I'm pretty sure you'll be able to reach focus. However, I've got some cautions for you.
I think you'll have some vignetting if you use it at the design distance to get f/3.3. You can see some samples of how the 3.3 works on this site: http://www.isomedia.com/homes/cvedeler/scope/focal_reducers.htm
(Note that the ST-7 camera has nearly the same size chip as the DSI 2.)
Note that the amount of reduction you get is dependent on CCD face to focal reducer distance so remember to take the distance due to the filter slide into consideration. This calculator may be helpful: http://timosastro.1g.fi/tools/focalreducer.html
Personally I like to use the reducer set closer to get less reduction.
al
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al
Meade 80mm APO
Celestron 6" SCT
CGE, GM-8, & CG-5 GT
ST-2000xcm, DSI Pro II, DSI Pro
( www.alberts-astro.com/astro )
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ryanr256
member
Reged: 04/21/09
Posts: 30
Loc: Southwest Ohio
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Thanks for the quick replies.
Would I be better off with the 6.3 FR instead of the 3.3? My initial impression was the the 3.3 would be more versatile but it may have issues which would negate the versatility.
I know I'll need an FR to image with the C8 and DSI Pro II, maybe the 6.3 is the better option?
Thanks,
-Bob
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Meade ETX60AT-BB
Celestron C8-SGT Advanced
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jgraham
Postmaster
Reged: 12/02/04
Posts: 6764
Loc: Dayton, Ohio
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I think you'll be much happier with the f/6.3 reducer. I use my f/6.3 all the time whereas I rarely use the f/3.3 reducer. You can also use the f/6.3 reducer visually.
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-John
================================================
Homebuilt scopes from 4.25-16.5"
Meade LXD75-N6/SN6/SC8, DSX-90, ETX-60BB, ETX-125PE, DS-2130
Orion StarBlast, BinoViewers, Coronado PST
Rebel XT/XTi, DSI Pro (I, II, & III), DSI, LPI, Electronic Eyepiece, Phillips SPC900NC
Tasco 60mm Refractors
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ryanr256
member
Reged: 04/21/09
Posts: 30
Loc: Southwest Ohio
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And there just happens to be one (Celestron 6.3) in the S&S.
Thanks for all the advice. It's nice to have helping hands when you are just starting out.
-Bob
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Meade ETX60AT-BB
Celestron C8-SGT Advanced
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rice224534
member
Reged: 06/29/08
Posts: 31
Loc: Tokyo
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I currently use this combo(C8+Meade 3.3FR +DSI ProII). With this, focusing is not problem even using longer spacer but a coma is a big problem. Nevertheless, I use 3.3FR because I get wider FOV than using 6.3FR. The spacing between 3.3FR and DSI Pro II is a critical for obtained focal ratio and coma. The longer spacer I use, the shorter focal ratio image I get but the much more bad coma. So I examined a compromise of coma and FOV wanted. I replaced the original filter holder on DSI Pro II with very low profile adapter from ScopeStuff. When using 20-30mm spacer, I can get wide FOV with nearly F3.3 but with a ton of coma so that I cannot endure to look this bad image. My compromise with FOV and coma is with using addtional 10-15mm spacer althogh I still see a few of coma in the edge and get only f4-f4.5.
According to the web site by Chris Vedeler indicated above, the combo with Meade 10" + Meade 3.3FR +30mm spacer+ ST-7E obtains excellent image with F3.3 FOV and no coma. I checked the collimation on C8 and added the IR-block filter on DSI Pro II. I dont know why my combo cannot obtain F3.3 FOV with no coma. I wonder if there is the critical difference in mirror between Meade and Celestron or in the quality of camera between SBIG and Meade.
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NS8GPS / Orbit Wedge
DSI Pro II / Outback Cooler Razorback
12.5" FRP Dob (Kasai Ninja-320)
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Al Miller
sage
Reged: 08/25/08
Posts: 415
Loc: San Antonio, Texas
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I think you may be happier with the f/6.3 reducer as well. I have both reducers and have never seemed to be able to get the f/3.3 to work for my C8 XLT. Vignetting was horrible no matter how I set it up. I have the f/6.3 reducer installed and just leave it there (unless I use the C8 to view and image planets). It's a better setup for me.
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Meade 10" LX200 Classic
Celestron C8 XLT OTA
Orion XT8 Classic Dob.
Meade AR-5, f/9.3 refractor OTA (LXD55 version)
Antares 4.1", f/12.4 refractor w/EQ5
Orion 110ED, f/7 refractor OTA
Orion ST120, f/5 refractor OTA
Orion ST80, f/5 refractor OTA (guidescope)
Meade DSIc, DSI IIc and DSI II Pro
Celestron NexImage (x2)
Orion StarShoot autoguider
Atlas EQ-G mount
Edited by Al Miller (11/04/09 11:09 AM)
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ryanr256
member
Reged: 04/21/09
Posts: 30
Loc: Southwest Ohio
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Cool. Thanks to everyone for the help. I just picked up the Celestron 6.3 from the S&S. My package from Astronomics came today. In it is the IR cut filter.
Soon I will be able to post some "noobie" images. 
-Bob
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Meade ETX60AT-BB
Celestron C8-SGT Advanced
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