This HaRGB was taken in two different periods. The Ha layer was taken in July 2011, and the colour data in May 2012. The Ha was the third image taken with the new scope from inner Melbourne on a favourable winter's evening (5 x 20min subs). The colour data was then captured in May 2012 in central Victoria under clear dark skies (7 x 300sec subs per channel).
Luminance layer added to star field [previously just bin2x2 data in star field] Half Size [2.0mb] Updated version Full Size [4.5mb] Updated version
Slightly cropped due to difference between the two FOV's - Ha & RGB
Instrument: Planewave CDK 12.5 / Focal Ratio: F8
Camera: STL-11000 + MOAG + AOL
Camera Sensitivity: Ha BIN 1x1, RGB BIN 2X2
Exposure Details: Ha 1200sec x 5 + RGB 300 x 7 [each]
Mount: AP900GTO / Autoguider: SBIG Remote Head
Date: 27 July 2011 [Ha] + 20 May 2012 [RGB]
Viewing Location: Melbourne [Ha] + Heathcote [RGB], Victoria.
Software Enchancements: CCDStack2, PS CS3
Comments: Clear Nights, Very good Conditions
Seeing conditions: 8/10
I continue to find HaRGB processing very difficult, combining the tight star data of the Ha layer to the larger star data of the RGB. In PS when completing the colour layering of the Ha as a luminance layer, and the RGB as the colour layer, I note the larger stars of the RGB Layer causes those dark rings, exactly like strong deconvolution causes. The issue that followed was a struggle for me to remove the unsightly problem. I’ve also noticed that the Ha data doesn't treat all coloured stars equally, in that some coloured stars don't even show up in the layer. I noticed this was a problem especially in the darker areas of my Ha with a lack of star density that was present in the RGB data.
To correct the star difference in size, I found using the Ha layer as the basis of a mask to the RGB data the best. I also used the minimize filter, but you have to be especially careful not to loose smaller coloured stars from the RGB altogether. So it became a ridiculous balancing act between minimizing stars to the Ha data star size, and being careful for the RGB data not to loose colour in the areas of the smaller stars [like the central region of the M16]. Eventually, I pasted over the top of the image those central smaller stars in the nebula, as it became just too hard in the end. To avoid divorce, I simply gave up on processing the outer stars in the darker regions, using a minimize filter just to resized them to and equivalent size to the Ha star sizes [some now look a little strange shaped]. At least this resolved the problem of the lack of star density in these areas of the Ha data.
Hope the above wasn't too much waffle!
Bye
Steve
Last edited by stevous67; 28-05-2012 at 08:32 AM.
Reason: Edited following comments - thanks for the feed back
You are really getting some tidy results there Steve. I must admit I miss the MOAG +AOL setup I had with the STL...sadly no AO-X seems to be in the SBIG skunk works for now...
Thanks again for the feedback. David and Dave were correct, using just the bin 2x2 data in the star fields wasn't a good idea. I've put back the luminance layer there at the expense of loosing some additional stars.
