British Astronomical Association, Variable Star Section (BAA-VSS)
Thu, 08/03/2023 - 21:00

The scope I am buying has a field flattener with it.

I have seen that some are described as flattener/reducers, but this is not a reducer.

Is this this of any use in the photometry optical train?

American Association of Variable Star Observers (AAVSO)
Hello! I was looking at at…

Hello! I was looking at at field flatter when I was considering purchasing a 12" f3 scope with a wide field CMOS chip.

    What focal length will you be using and what FOV for your imaging system?

    Several folks here walked me through what the defocus for edge stars would be if focused on the center and what defocus would be if I focused halfway out the image. They'll probably weigh in once you give some parameters.

    Even then, it only became an issue for wide fields that had few comp stars when I needed a comp star at the edge of the field with the target in the center because there weren't any other comps available - a pretty rare occurrence with what I wanted to image. Even with a wide field image, my goal was to have multiple targets in the frame and use subframes that had the comps for each target. As a result, defocus for targets and comps in each subframe would be minimal. Best regards.


British Astronomical Association, Variable Star Section (BAA-VSS)

Thanks very much Mike

Very clear.

My proposed initial system will be: StellaMira 90mm ED triplet, FL 600mm, CMOS camera ZWO – AISI 1600

I plugged this into:

and it returned a FOV of 1.69 x 1.28 degrees

Long term I'd like a big jump to a Celestron C11