Quote:
Originally Posted by bkm2304
Hi Andrew,
High contrast seems the go here. I also read there were probs with astigmatism because the light is off axis like a Herschellian.
What about an F20 mirror with a prime focus camera out on the end?
Richard
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That's a pretty good idea - the ZWO cameras are smaller than the secondary on most 20" newt, so you'd have 'better' contrast from secondary obstruction. Since mounting a 20"f20 would be reasonably expensive, maybe a 20" flat sidereostat in front of the 20"f20, with a small hole in the flat and the camera behind the flat, sort of like an inverse newtonian?