Which ASI camera for solar?

merlin66

I use both for my solar observing.

The ASI 174MM although it seems to suffer from Newton Rings (fixed by using the T2 tilter) I think performs better (due to the pixel size) on systems >1500mm fl.

The ASI 183MM doesn't seem to show NR and I think is better at focal lengths less than 1000mm.

Just my experience.

merlin66

The Quark has a built in x4 telecentric, so the final focal length is much higher.

I'd try the ASI 174.

Any frame rate will be always be secondary to the chosen exposure time, but around 20-30 fps will effectively "freeze" some of the poor seeing.

(On the spectroheliograph I use, where I only record the spectra line of H alpha, I can get up to 400 fps)

The NR are caused by interference (when using very narrow band filters - like the H alpha etalons) between the surface of the CMOS chip and the glass cover plate. Not all cameras are affected. The ASI 183 has an AR coated cover plate which I think may help.

For me, the T2 tilter works.

Hope this helps

merlin66

The action of the tilter is to effectively cause a slight increase the spacing between the glass plates, and hence reduce the NR.

In my case the amount of tilt on an ASI 174 worked out to be about 1 degree.

The tilter can be easily adjusted just by noting the NR on the computer screen during recording and making the adjustment until no NR are seen.

100_3362.JPG

12_11_39_no tilt.jpg

12_17_35_tilted.jpg

merlin66

Hmmm

I haven't seen an issue like that before.......

I'm not sure the tilter would fix the problem.

Is it related to the acquisition software? I use FireCapture V2.6

Best I can offer would be to upload those images to the Solar Chat forum and ask the question.

https://solarchatforum.com/

merlin66

The solar disk is only 1/2 degree in diameter.....

This size doesn't require any flattener etc, and it's best not to include too many added optics.

I regularly use a x2.5 Powermate to record surface detail/ proms.

Support@ZWO

nice shot!