Back Focus Issues

[Ghost_Returns (Richard)]

I have a newbie question

I tried my first shoot of the full moon last night through my scope C10-NGT Computerized Telescope, I connected my Canon 40D with my T-piece and then to my 1.25" eyepiece, and found that I could not focus in on the moon.

What length extension tube do I require to achieve this focus?

I then used my Baader Hyperion 8-24 zoom and hooked it up to my camera and was able to achieve enough focus with it to take photo's.
However they were not super sharp, so I guess further experimentaion there.
Basically I was using my Baader Hyperion at 24mm, and can see approx 3/4 of the moon for photographing.

Any ideas, thoughts would be greatly appreciated !!!

[bmitchell82 (Brendan)]

well one of the quickest ways is to hold the camera with no T thread and slowly move it back untill you see the moon focus (considering you have something like live view this will be easy) and then once it has moved though the focal point and blurs again that should be the aproximate distance you need.! good luck cheif you have some really nice dark skies where you are i should know im a born and bread NT man myself.! that lived out on the stations!

[Merlin66 (Ken)]

It's more normal to use the DSLR with a T2 adaptor and a 1.25" nosepiece with a Barlow if needed than to use eyepiece projection. For eyepiece projection, you need a special adaptor which holds the eyepiece and allows the camera body to be fitted behind ( This may be what you're saying?) The distance between the eyepiece and the CCD chip is important. The further the distance the greater the magnification. You'll need at least a 25mm or greater focal length eyepiece to get reasonable FOV. The camera body is 55mm deep so the connection should be as close to the rear of the eyepiece lens as possible, this will give approx. x2 magnification.