Re: [APML] the few, the proud, the insane...

[Chris1011@aol.com]

In a message dated 7/17/2002 9:21:24 AM Central Daylight Time, tonyhallas@foothill.net writes:


> The pros use narrow band filters and crunch numbers... I am not sure our images have much use to them... still, there are too many blue stars in M13...   : - )


The weather finally co-operated and I was able to capture some images of M13. Since my goal is high resolution, I usually work with LRGB. Adding a luminance layer dramatically decreases the noise and allows a bit of sharpening to bring out the most in the original image. However, this also kills the star colors, tuning most of the bright ones pure white. M13 has a lot of old yellow and red stars, as well as some fainter blue ones. To bring out these subtle colors, I added a color layer in Photoshop on top of the LRGB image using the RGB image as the color layer. The result is that the brighter stars returned to their pale yellow color. 

The image is at: http://groups.yahoo.com/group/ap-ug/files/Astro-Photos/M13CLRGB1.jpg

This image of M13 was taken with the AP10" Mak-Cass - LRGB 20/10/10/10 minutes exposure with SBIG ST10E and CFW. (P.S. the image is a mirror image because I shot through the AO7 module, but I did not use the AO7 for guiding).

I believe the same method can be used with film. By taking two exposures, one with color film, and another high resolution B&W using Tech Pan, one can make an LRGB image. The colors can then be added back in using layers in Photoshop. Anyone game to try?


Roland Christen