Re: Intermediate ATM project

[epabcc@epa.ericsson.se (Bratislav Curcic)]

> What is the shortest F ratio you would recommend 

It all depends on what do you want. I was personally thinking about
something around f/15 to f/20 (planetary scope). Making one at f/10 
is feasible, but field of view gets rather narrow.

> what is the best way to go about making and testing a large ellipse primary?

Conjugate foci testing (null test). If that's not feasible, Ross null test.

> Would the OTA be roughly half the focal length?

It depends on what secondary magnification do you choose. But yes, it
will be less than primary's focal length.

> Does anyone have a source/recommendation of good info on this design?

As usual R & vV has enough infomation for starting the evaluation.
Also, as usual, a good ray tracing program and few hours spent in front
of a computer will help a lot too. Keep in mind that images on the
computes screen often look much worse than in reality (especially if
coma is involved). In other words, do final ray tracing with enough
rays to see the 'real' light distribution in the image.

Bratislav