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Waht scope is better?

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#1 jerry32

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Posted 05 December 2012 - 05:16 PM

So i have a co-worker who is debating between these 2 scopes.
http://www.celestron...c8-sgt-xlt.html
http://www.celestron...on-c10-ngt.html

The use would be AP and General observing in mildly Light polluted area.

#2 drewp

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Posted 05 December 2012 - 05:26 PM

for ap the c8 would be better on the cg5 mount than the giant wind sock called the c10n. the c10 on a cg5 is imo too much weight on that mount. the c10 would be better for visual.

#3 Bob Griffiths

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Posted 05 December 2012 - 05:59 PM

I agree with drewp... the C10 newt is one BIG scope and a Cg% mount just is not up to teh task even in a very slight breaze..

The difference visually is honestly not a heck of a lot..mostly the Newt would give you a brighter view and a wider FOV..both noticeable enough difference to come close to being a WOW what a difference BUT not

I admit that I am a Sct and Refractor guy and have now owned a Newt of any kind in over a decade..

Bob G

#4 Ed Whitney

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Posted 05 December 2012 - 06:06 PM

The C8 is better, but you will need a F/6.3 FR-FF for AP to correct for the serious field-curvature SCT's have.

But, this could be a tough choice for you because the 10in scope "can" reveal delicate pastel colors in Jupiter and details in Mars that the C-8 can't for visual. The 10in newt is perhaps the max weight the CG-5 can carry, but it will shake some. The other poster is right about the wind causing you some real aggrivation when taking pix.

The C-8 is better suited for AP with a CCD or DLSR camera, while the newt may be better with a web cam where you can stack pix and remove the unwanted frames.

Essentially, in MHO, a 10in dob is better suited for reflectors. The Alt-Az mount is rock solid holding the tube and it's more easily transported and set up than the C8 on a CG5.

Clear Skies! :)

#5 panhard

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Posted 05 December 2012 - 06:40 PM

The 8" is the way to go.

#6 jerry32

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Posted 05 December 2012 - 07:12 PM

ok so hes leaning towards the 8 inch but hes wondering if his camera
http://www.dpreview..../sony_dschx200v

can be used to do some AP? If it is what adapter will he need..

thanks all

#7 lamplight

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Posted 05 December 2012 - 07:18 PM

I have that 10",Reflector. First thing I had to do was spend a lot more$ on asturdier mount. Even for visual Weare talking 15+ seconds for it to stop shaking after a focus adjustment. WITHOUT any wind.

#8 panhard

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Posted 05 December 2012 - 07:26 PM

If you don't get a reply to the question about the camera and adapter soon ask that in one of the imaging forums. ok

#9 jerry32

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Posted 05 December 2012 - 07:37 PM

If you don't get a reply to the question about the camera and adapter soon ask that in one of the imaging forums. ok


thanks will do :D

#10 rdandrea

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Posted 05 December 2012 - 08:37 PM

"Better" is subjective. However, I think that a 10" steel-tube Newt might be pushing the CG-5. It will handle the weight (barely) but the moment arm of the big scope will make the mount a little fidgety. I have the C8-NGT and I would not want to go longer and/or heavier.

Also, even my 8" requires three trips out of the house to set up (four if you count a trip for my eyepiece case, flashlight, etc.) One for the mount, one for the counterweights, and one for the OTA. I think it might be easier to haul out the SGT, and the best scope is the one you use most often.

#11 S.Boerner

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Posted 05 December 2012 - 09:02 PM

I did a quick scan for the Sony camera manual and don't think it has a lens that can be removed. If he can't get the lens off the camera he's going to be stuck doing afocal if he wants to use his scope. Google afocal to get an idea of what that means.

IF he can get the lens off the camera he'll need a t-mount adapter for the camera and then either a 2" or 1.25" nose piece that will allow the camera to mount to the scope's focuser. Go to agenaastro.com and search for "nose piece" and you'll see what I mean.

#12 Erik30

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Posted 05 December 2012 - 09:07 PM

I have that Sony camera, the lens is not removable.

#13 Pharquart

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Posted 05 December 2012 - 09:09 PM

ok so hes leaning towards the 8 inch but hes wondering if his camera
http://www.dpreview..../sony_dschx200v

can be used to do some AP? If it is what adapter will he need..

thanks all


I wouldn't recommend that camera for AP. From what I can see, the lens on that camera is fixed. That is, you can't take it off and replace it with a different lens.

There are 2 types of astrophotography: prime focus and afocal. With prime focus, the camera itself doesn't have a lens, but rather uses the telescope as its lens. Instead of a lens, the camera gets an adapter that fits into the focuser of the telescope (the camera becomes an eyepiece). Most "good" astrophotographs are done this way.

Afocal photography can be done by anyone with any camera. In afocal mode, you simply hold the camera up to a regular eyepiece and take a picture. The camera replaces your eye at the eyepiece. It's very hard to hold the camera exactly in the right spot to get a good view with no vignetting (getting a smaller than normal view). There are adapaters like this one to help. These clamp onto the eyepiece and provide a mount for the camera. These work pretty well with basic point-and-shoot cameras. The particular camera you list looks fairly large. The weight might be a problem. Also, the lens on that camera sticks out a long ways, which might be out of the adjustment range of the mount.

For photography of planets, basic imagers use a webcam adapted to mount in the focuser. They then take videos (lots of pictures), select the ones that are sharp in focus (which varies from frame to frame due to atmospheric turbulence) and stack the frames to get a composite shot.

Brian






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