M57 and its outer shell

This image was taken on two separate evenings. On the first I captured the RGB colour data with total exposure times of thirty minutes for each  filter . however on the second evening I used a total exposure time of three hours using an Astronomik H Alpha filter . The sky conditions were fairly clear with stars visible down to magnitude 4.5 . I captured five-minute sub-frames with matching dark-frames and combined them with flat field frames to reduce the effect of vignetting in the final image . The telescope I was using was a ten inch f/ 4.8 reflector on a Vixen Atlux mount, PHD auto guiding and an Atik 383L mono CCD camera. Notice the galaxy IC1296 near by M57.

RGB

RGB + H-alpha

RGB + H-alpha cropped