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Largest newton on CGE?

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#1 Frank

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Posted 14 March 2010 - 01:33 AM

I'm actually owning a CGE1400 - and I'm very happy with it. But for some objects, I do need a larger FOV. Therefore I'm considering to build a newton OTA - grinding the mirror myself. What's te largest newton for visual use on a CGE? 12"? 14"? 16"?

#2 Doug76

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Posted 14 March 2010 - 09:55 AM

Weight-wise, you could likely make any of those ride on it. But the length of the OTA is what is going to kill that idea. At best I see a 12" f/4.

#3 rmollise

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Posted 14 March 2010 - 10:01 AM

I'm actually owning a CGE1400 - and I'm very happy with it. But for some objects, I do need a larger FOV. Therefore I'm considering to build a newton OTA - grinding the mirror myself. What's te largest newton for visual use on a CGE? 12"? 14"? 16"?


A fig? Oh NewtonIAN! My bad. :lol:

Seriously, mostly this depends on the focal length of the scope, as the length/lever arm is more critical than just the weight.

I would not go beyond 10-inch f/6.

#4 Frank

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Posted 14 March 2010 - 10:09 AM

10"f/6? I was thinking about 12"f/4 or 14"f/4 or similar ...

#5 rmollise

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Posted 14 March 2010 - 11:55 AM

10"f/6? I was thinking about 12"f/4 or 14"f/4 or similar ...


You might get by with the 12-inch f/4. The 14-inch? Not So Much. Not given my experiences with the C14 on this mount, anyhow, and for picture takin' Less is always More. ;)

#6 mclewis1

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Posted 14 March 2010 - 02:22 PM

I'm actually owning a CGE1400 - and I'm very happy with it. But for some objects, I do need a larger FOV. Therefore I'm considering to build a newton OTA - grinding the mirror myself. What's te largest newton for visual use on a CGE? 12"? 14"? 16"?

Frank,

That answer also depends on the construction of the scope. An open truss type of construction method would offer two advantages, one is less weight and the other is less surface area for a breeze to act on. Truss type of construction is more complex and more costly than a simple solid tube so you'd have to gauge your capabilities accordingly. With truss type of construction you might be able to get away with a 14 or a really short focal length 16" scope on a CGE ... but that would IMHO be a lot of cost and effort for a second imaging scope.

But I think you might consider some other imaging options for wider field work (assuming you're looking for focal lengths shorter than that of a C14 with the F6.3 reducer). How about your C14 with a Hyperstar? With a Canon DSLR you'd have a fov of approximately 1 x 2° and a focal length of around 700mm.

#7 galacticphoto

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Posted 15 March 2010 - 07:25 AM

10" f/5 or f/6 of conventional design (w/ guidescope, mountings, and cams) if being used for AP. If used for visual only, try a 12". Anything bigger will require too much attention.

The CGE is a nice small mount, and will do a good job is not overloaded.

Robert






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