> My initial thoughts were to create a Ross corrector combination.
> The optician friend of mine is a mirror pusher as well. We think
> that it might be doable.
The "original" Ross was a three element design. I guess that for such fast parabola you will need 3 elements too. For slower f-ratios (f/4 or so) you might get away with only 2 element corrector. Not bad idea if you cannot afford antireflection coatings.
Have you tried ray tracing ? Are you sure that even Ross will cover 35mm at 8" f/2.8 ?
> I would opt for the massive standard newt secondary. I haven't figured
> out the exact size though. I would imagine that it would be in the
> 3 - 4 inch range. It would most likely be designed so the tube
> would be very tight to the primary to minimize the distance the secondary
> would need to throw the light.
Don't squeeze it too much - you'll need some room not to vignette by front of the tube.
> Any thoughts about optical quality as seen on the film ?
I stopped figuring my Wright when I was sure that images are well below 10 microns. At f/2.8 this is some three times larger than a diffraction disc. I have never seen images on the film smaller than some 12 microns or thereabouts. Rutten & Venrooij accept anything smaller than 25 microns for an astrophotographic instrument. I find it a bit too loose - I can accept 30 microns in the very corners of 35mm, but I'd like it better at the center.
> A) Would a massive 40% - 45% central obstruction be that noticable ?
No.
> B) Think the primary will be a challange ? I love a challange.
Yes. It could be bigger challenge than you expect.
> The idea seems to be more appealing to me than having the curved single
> film idea of a Schmidt camera.
You are forgetting one simple fact : an 8" f/2.8 Newtonian will have EXACTLY THE SAME curvarure of the field as 8" f/2.8 Schmidt camera ! And at focal length of 560mm (sorry, 22 inch), it is far from insignificant. And yes, you can make field flattener for a Schmidt camera too.
> A Ross corrector leaves the film in the
> camera, ready to have a 50mm standard lens placed in front of it. This
> is very convenient.
Yes. That's why I opted for Wright. Another design well worth looking into is concentric Schmidt-Cassegrain. One of these days when I win a large Byers mount on a raffle ... Good luck,
Bratislav