Part Of M42, Nothing Fancy...

[Ian McCallum]

I did some imaging of part of M42, this evening.  The setup was the usual SW ST120 achro, with a ZWO ASI224MC camera (fitted with Baader Contrast Booster and IR/UV cut filters).  I took 20 x 10sec subs and the same number of darks, at the same exposure and gain settings, etc.  There is more detail in the image, but I'm not great with teasing out the best details...😕

[Ian McCallum]

This was done in Unity gain, would it be better in zero gain, therefore better dynamic range? 

[Phillyo]

It looks like your focus is slightly off, I'd work on getting accurate focus first. Leave gain and offset to defaults, not much to be gained by changing them really.

[Ian McCallum]

23 hours ago, Phillyo said:

It looks like your focus is slightly off, I'd work on getting accurate focus first. Leave gain and offset to defaults, not much to be gained by changing them really.

There were some passing clouds during the exposure, could that have caused the problem? 

[Phillyo]

Possibly, but you should have removed those frames from the set before stacking the data no?

[Ian McCallum]

19 minutes ago, Phillyo said:

Possibly, but you should have removed those frames from the set before stacking the data no?

I'll recheck the subs later. The stacking was done in DSS. 

[Padraic M]

Definitely check on focus. I find that adequate focus is hard to achieve without an electronic focuser (others disagree) but either way, sharp focus makes a big difference. Cloud tends to reduce overall contrast, rather than sharpness.

Do you need those filters at all? Less glass between you and the target tends to be better, unless you have a specific reason. And, of course, once you have your setup dialled in, many times more subs will be required!

[Ian McCallum]

1 hour ago, Padraic M said:

Definitely check on focus. I find that adequate focus is hard to achieve without an electronic focuser (others disagree) but either way, sharp focus makes a big difference. Cloud tends to reduce overall contrast, rather than sharpness.

Do you need those filters at all? Less glass between you and the target tends to be better, unless you have a specific reason. And, of course, once you have your setup dialled in, many times more subs will be required!

I didn't get a nice bright star to use the Bahtinov mask on, that night.  I need the Contrast Booster filter, due to the chromatic aberration of the achromat.