M8 and M20 APS-C 200mm widefield

[Rowland]

This one I took almost 3 years ago. At the time I had just discovered dithering and set up a mechanism on my manual GEM to manipulate the hand controller keys to shift RA and DEC. The whole thing is coordinated with image capture. I don't know what happended to the calibration frames and as you can see the camera was not modified (Canon 1000D).

I've always liked the potential of this image but never sat down with it for some serious processing. Enter StarTools. Yes it was stacked manually in that other program - not DSS. There was no batch script at the time. It's a bit blocky because of binning.

I am curious about the star colours because I have gone to great lengths with my widefields to find settings that show off the wide variety of colours. I'm pretty sure this was taken at ISO 400 and 3 or 3.5 minute exposures f5.6 and about 40 subs/lights. The Colour Scientific Setting was used - I have not seen the oranges and blues before - more dynamic range than I thought, or am I just imagining things.

Anyway, with no time to do any imaging, here is one of my first teeth cutting efforts.

[admin]

Very nice!

Colors look spot-on for the nebolsity and the right part of the image. I'm indeed not sure about the left part, which is very biased towards yellow. Could it be a gradient issue?

[Rowland]

I think it is gradient. This image linear has a very rich green cast, which is very difficult to remove, unless I follow up with the PI colour noise reduction tool, but if I understand your point in another thread, these tools effectively reduce brightness data - tried a more aggressive Wipe setting with slight improvement, but how aggressive can/should I go?

[admin]

I think it is gradient. This image linear has a very rich green cast, which is very difficult to remove, unless I follow up with the PI colour noise reduction tool, but if I understand your point in another thread, these tools effectively reduce brightness data - tried a more aggressive Wipe setting with slight improvement, but how aggressive can/should I go?

Have you tried the Vignetting preset with a slightly less aggressive 'Corner Aggressiveness' than the preset value (which is 100%)?

[Rowland]

Vignetting as described worked well. As suspected there was no calibration of lights, evidenced by black spots.