Horsehead and Flame

Well this is my first attempt at RGB processing so take it easy on me 8) . Although I have some fairly good data I'm getting huge reflections in the blue channel which destroys an otherwise OK image. Its not from chromatic abberation in the OTA. There is something going on between the CCD cover slip, or cover glass and the filters. Not to sure if they can be processed out or not, especially the gigantic blue cloud around Zeta which turns purple when blended with the R. Thanks for looking, Vince

Borg 77ED ST-2000XM
HaRGB 360:90:90:90
Used the Ha for Luminance at only 25% weight. To realize the full potential of the Ha without messing up the color I may have to try a blend of Ha+R for the red channel.

Attached Image:

Hi Vincent,

Very well done! As you have found out this is a very hard region to process due to Zeta Orionis and other stars. The halos are internal reflections generally from light reflecting off the CCD chip -- back to the coverslip -- then back to the CCD chip. Here is an excellent review by Don Goldman:

http://www.astrodon.com/documentation/documentation.cfm?DocID=3

The halos can be processed out but really don't distract from a well done image. The only way to not get halos is buy a camera that doesn't have a CCD coverslip such as made by FLI or Trifid. All SBIG cameras have coverslips.

Best,

Tom

That is, indeed, most excellent, Vincent.
I'd show you my first RGB, but I destroyed all copies to avoid embarrassment and to avoid blackmail.
As you can see, the long RGB exposures provide rich color.
As Tom indicated, this area is a minefield for reflections and most imagers just leave them in.
Congratulations on a fine image.

dan kowall
photonhunter.com

I think it is fantastic! The reflections don't detract at all.

Thanks for the kind comments guys. The RGB processing is alot more challenging than I expected. Its interesting that if you stare at an image with messed up color long enough, it starts to look good to your eye. Then you walk away from the screen and when you come back....WHOA! how did it get that messed up?? 8O

Vince,
I like the shot a lot. Nice color, nice Horsehead. I guess the ST-200XM anti-blooming works good for you. Imagine the processing you would have gone through with an ST10.

I believe I too am struggling with some glass interface reflections. I think I'm going to go through a range of trial shots to see which glass causes the most problem - it will be interesting to see.

Very, very nice for a first attempt at RGB imaging. Thomas' explanation is correct--you do have a problem with refelection from the CCD back and forth with the coverslip. However, you also do have some slight CA in there, too. That Borg is not a perfect apochromat, and the halos around even the dimmer stars show that. All but the absolute best APOs will have that problem and you can just process it out. Takes a little extra work, that's all.

Great first RGB--one to be proud of.

Jeff