[Placidus (Mike and Trish)]

Thanks everyone for sensible and helpful comments extensions and advice. I'm learning.

Originally Posted by Shiraz

I suppose that the other thing that could be said is that, if you can get the same (or better) result from much shorter subs, there is no need for deep wells.

That had vaguely occurred to me too. A good point.

Originally Posted by Shiraz

M&T, the other issue that should be noted is that current CMOS chips have small pixels - they do not match well with long fl scopes, so let's hope that someone eventually brings out a mono CMOS full frame camera with large pixels.

Another very good point, not just for CMOS but in general.

Originally Posted by Shiraz

FWIW, suggest that the equation for sky limited imaging is:

SNR = N*Q*T*P / sqrt(N*Q*T*P + N*Q*T*S + N*T*D + N*RN*RN)

where S is the sky signal and D the dark current ... ... ...

Thanks, Ray, that's excellent. You've written the equation in a way that is clear unambiguous and intuitive. It'll take me a while to scrape together the relevant numbers and plug them in.

Originally Posted by Atmos

Here is a camera for you MnT
A little over 2e- RN, 350k e- wells and pixel sizes that really suit your long FL

It is a great discussion in this thread btw

Wow! That is a big beast. Some of the 60x60 mm real estate would be wasted on us mere mortals with 50 mm filters.