View Single Post
Old 29-06-2015, 11:03 AM
gregbradley's Avatar
Registered User

gregbradley is offline
Join Date: Feb 2006
Location: Sydney
Posts: 15,409
Good point Rally.

Pixels with microlenses are sensitive to the angle of incidence of the light rays. So most camera sensors require light to strike the pixel within a certain angle.

So faster scopes with light rays at a steeper angle may tend to vignette more.

Centre sharpness, corner performance, vignetting,varying spot sizes over the field of view would come into it. Some scopes have greater vignetting than others. Some have a bit of a bright spot in the centre and vignette out at the corners more.

Some sensors will cope with steeper rays than others. Some filters are less effective with steeper rays.

I recall with Planewave that the designer has a few parameters they can play with but they are conflicting. F ratio, vignetting, corner correction may be conflicting targets.

Gapless microlenses, no cover slip glass affect QE.

A lot of scopes barely cover a 16803 chip. That's where Tak FSQ, BRC250 and AP scopes are so good. AP in particular have huge illuminated corrected circles. Something like 100mm. Massive and would handle a Medium Format camera.

You are not going to be able to use a full frame or above sensor on anything with less than a 3.5 inch focuser so that is a more practical aspect of the comparison sheet results. Which of those combinations can actually handle that sort of sensor?

Reply With Quote