Image circle for Eyepiece projection

[rally]

Just wondering if anyone knows a method to calculate the image circle diameter in a system using eyepiece projection ?

Can't seem to find any references to this anywhere :(.

In this case the EP's are Abbe Orthoscopic 2.8 or 5mm on a f7.3 refractor, 1100mm and the exercise is to attempt to calculate the largest CCD chip possible.

Thanks

Rally

[Paul Haese]

Why would'nt you use a barlow over the EP projection method? EP projection is rarely ever as good as barlow and CCD.

[rally]

Paul,

Its a question of what I have in my box and also the 'X' times factor.
I would like a lot more than 2-5x.

The chip I would ideally like to illuminate needs about a 35mm image circle, which I don't think will work, but it led to exploring about how to calculate it and I wasn't able to find anything on the search engines.

So I was hoping the Borg collective might have had some insight !

Cheers

Rally

[frolinmod]

This is not an answer to your question, just me inserting opinion where it is probably not appreciated and probably doesn't belong, but...

In my experience Eyepiece Projection is the most time wasting, frustrating, difficult and touchy form of photography there is, bar none. It's just plain EVIL! It is trivial by comparison to get good results using a barlow. I gave up on Eyepiece Projection over 30 years ago and never looked back. I don't know anyone who still uses it since the advent of good barlows. Good luck! :eyepop:

[rally]

Thanks Steve,

Some interesting stuff there and useful, but not quite what I was after.

Frolinmod,

Opinions always appreciated !
I agree - I am not expecting a quality result, but at this stage its still much cheaper and easier to explore this with eyepiece projection than a 100mm diameter chunk of customised precision optics to trial an idea !

Cheers

Rally