whats wrong with my star colors?
Posted 10 December 2012 - 01:31 PM
Posted 10 December 2012 - 01:36 PM
Posted 10 December 2012 - 01:48 PM
Assuming the filters were in the correct positions for what the software expected:
Did you G2V balance your filters and sky conditions or just accept what the filters gave you? The latter rarely works. The E series from Astrodon is a better match to that camera than the I series but no where near perfect. Then too where an object is in the sky will alter color balance significantly with blue being lost as the object gets away from the zenith. Smoke, water vapor, dust and other factors will change the color balance as well.
Or if you have plate solve software use eXcalibrator for even better color balance -- especially when imaging in an area covered by the SDSS. NOMAD data is less reliable but usually better than G2V I've found.
Posted 11 December 2012 - 02:35 AM
Mike: It does look better indeed, but the stars still have that orange look.
The globular BTW is NGC104 (47 Tucanae).
I got the folowing image on Google just to get a perspective on the colors of NGC104. The image shows a lot more blue and white stars.
Posted 11 December 2012 - 10:26 AM
Also, here you say you have a pollution filter. Well, recently i tried M13 with a DSIc (color ccd) and the orion Skyglow filter. I didn't process anything but if I had to do it, (after extracting the RGB from the CMY since it's a color chip) I would have assumed that I needed to boost the green channel (since the orion skyglow fliter removes lots of green, see: http://www.telescope...s/125-Orion-...
But to my greatest surprise, the picture of my DSIc+Skyglow came out completely green before any kind of processing.
Boosting the green for processing would have made it worse! How come it came out green when the filter already removes green? I don't know. The output was directly in jpeg, maybe that was the problem but anyways, now i have mixed feelings about skyglow filters and color ccd chips. Definitively i should not have used it here. It's probably only good for a luminance channel on a black and white ccd.