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CGEM and 10" Newt

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#1 wsuriano

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Posted 19 June 2009 - 06:53 AM

Can a CGEM handle a 10", 27 pound (+ rings and dovetail), 47 inch Newt? I'm thinking of the Newt for visual use only, so I guess I'm worried more about handling the length than the weight.

Bill

#2 chollman

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Posted 19 June 2009 - 08:31 AM

I think yes. My CGEM easily handles my 70" long 8" F/8 with 80mm guide scope, finder and DSLR which total about 30lbs. I believe it could take even more. You will need an extra counterweight. The tripod is too high for newtonians, so I removed the original tubing and replaced with shorter and heavier tubing from the local hardware store. A very simple fix. See picture...
Charlie

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#3 tim53

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Posted 19 June 2009 - 10:25 AM

Charlie:

That's a nice looking scope!

I've been thinking of doing something similar with my NJP mount. its' got the tall tripod, so it's way too tall for Newts, but it's such a great mount, it seems a shame to not have a set of squat tripod legs for my newts.

-Tim.

#4 chollman

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Posted 19 June 2009 - 11:40 AM

Thanks Tim. The cost wast just 35.00 to switch out the legs. They are basically half the length of the originals. Way easier to use the newt now. Although a pier would be a better choice since the tube can hit the legs near the zenith. The CGEM can counteract this by programming limits into the hand control. I keep it about 12 degrees from the zenith and it does not hit the legs. Great feature. So far a great mount with some unique features. Charlie

#5 NHRob

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Posted 19 June 2009 - 12:57 PM

Charlie,
Very nice. Do you find you need rotating tube rings with the newt?

Rob

#6 chollman

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Posted 19 June 2009 - 01:16 PM

Thanks Rob. If I loosen the rings I can use the handles I installed to rotate. I find that if I initially set in the right place I really don't need to rotate very much. Rotating rings would be nice, but they are very expensive and look like they weigh a lot. I try to keep the weight down. My tube assembly is very light, about 17 or 18 lbs. The Protostar tubing is light and easy to work with. And their flocking by the way is excellent. Highly recommended for those wanting to make an 8" or 10" Newt. Charlie

#7 NHRob

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Posted 19 June 2009 - 06:33 PM

Hi Charlie. Nice. I've considered using the Protostar tubing before. For now I am taking a sabbatical from scope making and treating myself to a TEC-140. I may just build a planetary newt 7-8" someday and try that.
Your newt must be great on planets.

Rob

#8 chollman

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Posted 19 June 2009 - 09:01 PM

Rob, I just resurrected my mirror recently. I made it when I was 15 and had it refigured by Cave in 1971. It lasted for a few years into the 1980's then fell into disrepair and I was only able to save the mirror. In the last year I sent it in to be recoated and tested. It tested at better than 1/25 wave and .99 Strehl. Wow! What a surprise! I knew I just had to build it into a nice scope. The views are great. I just installed an Antares Optics 1.3", 1/30 wave secondary to match the mirror. Contrast is the best I have seen. Very sharp images too! I have the primary adjustable to move it closer to the secondary which enables me to prime focus and webcam. Still in the getting to know the scope and mount phase however. I hope to have great success and enjoyment with this scope. Jupiter is next. The moon is fantastic through this scope. Sounds like you are not lacking either with your TEC-140. I bet the views are tremendous. I have heard a lot of good about that one. Enjoy!...Charlie

#9 Luigi

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Posted 20 June 2009 - 07:53 AM

I've used a 10" Newt on an Atlas and it was unacceptably wobbly. IMO much of it was due to flex in the Vixen style dovetail spanning between the tube rings. The CGEM uses a much beefier dovetail and saddle so should be better in this regard.

#10 dvb

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Posted 20 June 2009 - 12:14 PM

I have a 10" Newt on an Atlas, with rotating rings, and I'm very pleased - but it was necessary to upgrade the saddle to a Losmandy-type ADM.

#11 Steen27

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Posted 21 June 2009 - 08:35 PM

Hi Charlie,

Great lookin scope!

Question on the BlackLite Tube... Do you think it would be strong enough for a 10" scope (12" BlackLite tube) with a feathertouch focuser and a dslr hanging on the front end?

It looks like you have a dual speed frocuser on there with a dslr on yuor 8 inch - did you have to reinforce the tube at the focuser or is it rigid enough?

Thank you for your time,

Jim

#12 chollman

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Posted 22 June 2009 - 01:13 AM

Hi Jim. No, I do not reinforce the tube. It is plenty strong. I am not sure about a 10". I would give it a try. If it works out, you would have a light weight 10" newt that would ride well on the CGEM. What focal length are you talking about. Anything F/5 or less would definitely work out in my opinion. Charlie

#13 PhilCo126

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Posted 22 June 2009 - 04:25 AM

Also noticed the orange ADMaccessoires knobs & saddle...
:D

#14 Steen27

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Posted 22 June 2009 - 10:07 AM

Charlie,

Thank you for your opinion on the BlackLite Tube... I think that is the direction I will go with when the time is right to finsih building my 10" f6... Plans are to build it to use as a dob for now - then later when the funds are there - buy a mount for it (dreaming of AP but budget will keep me at a CGE price point).

Bill - hope I didn't side track your thread too much...

#15 chollman

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Posted 22 June 2009 - 12:51 PM

You're quite welcome Jim. I guess I'm guilty also for taking over Bill's thread. But then again, he only posted that one time. I hope this has been helpful for Bill or anyone else considering a CGEM for their newtonian. Charlie

#16 wsuriano

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Posted 22 June 2009 - 05:08 PM

Charlie:

No problem. I got the answer - if I'm going to do this make sure I use a Losmandy dovetail - and got to see a cool scope as well!

Bill






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