SaratogaSkies Jim Solomon's Astropics

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M57 (The Ring Nebula in Lyra)

Image Details:

Camera: Mofidied Canon Digital Rebel (300D): Hutech (no filter)
Mount: Celestron AS-GT
Scope: Celestron C8-N (8" f/5 Newtonian)
Configuration: Negative Projection (Barlowed)
Additional Optics: TeleVue 2x Barlow
Filter: None
Effective Focal Length: 2250mm
Effective Focal Ratio: f/11.1
Exposure: 30 x 1min @ ISO 1600
Total Exposure: 0hrs, 30min
Date: 6/5/2005 12:40:39 AM PDT (start)
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: Manual
Guiding: GuideDog via Philips ToUcam Pro II (840k) through Orion ST80 w/ Celestron 2x "Kit" Barlow

Processing:

  • IRIS: Dark subtraction, Flat field, Best frame selection, Registration, Gradient removal, Richardson-Lucy deconvolution, LRGB computation
  • JimP: RGB to Luminance conversion (NTSC weighting), Kappa-Sigma stacking, White balance, ASINH stretching
  • Photoshop: Levels, cropping, JPG conversion
  • Neat Image: noise reduction

Image Description:

This is the Ring Nebula, aka M57, a spectacular planetary nebula in the constellation of Lyra. I'm very proud of this image, as it was taken with a long focal length (2250mm) on a very windy night with horrid seeing. Don't believe me? — then check out this, that, and the other threads on the TAC mailing list describing the conditions in and around the Bay Area on the night of Saturday, 6/4/2005. Told ya!

I'm becoming convinced that the best way to image DSOs at long focal lengths — especially with modest equipment in lousy seeing — is to take a page out of the webcam approach to imaging planets. Namely, take a bunch of short exposures, toss out the bad ones, and stack the remaining ones. That's what I did here, selecting the best half of the 60 frames, and then applying a liberal dose of Richardson-Lucy deconvolution to the luminance channel.

For this image, I used fellow Saratogan Rich S.'s modified 300D, which I think helped to capture a bit more of the red in the outer reaches of the nebula. (Thanks Rich!) Check out my previous attempt at M57 for a comparison. This is the full-resolution image, cropped for display on the web. North is up.