A set of 15 light frames of M15 along with 20 dark, 20 flat, 20 flat dark, and 20 bias frames all in raw CR2 format from a Canon 50D were collected using a 203mm TMB APO at F9. The light, dark, and bias frames were all ISO 200 and 10 minutes each. Flat and flat dark frames were 1/25th second exposures at ISO 200. The flat frames were taken during the day using a uniform gray or blue part of the sky. Detailed processing of the initial light, flat, dark, flat dark, and bias image set is demonstrated by the DSLR Automatic Image Set Processing example.

The goal is to enhance the stacked image for display on the web.

Initial stacked image

Step 1

Digital Development brightness and contrast increase.

Step 2

Digital Development color adjustment.

Step 3

Neutralize background and andjust color.

Step 4

Adjust Color Balance.

Step 5

3 iterations of background smoothing.

Step 6

Smooth finest detail and sharpen fine detail.

Step 7

Increase color saturation.

Step 8

Scale the image by 0.5 for display on the web.

Final image of M15. Stack of 9 x 10 minute ISO 200 with Canon 50D and 203mm TMB APO at F9.

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