SaratogaSkies Jim Solomon's Astropics


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Fire (Henry Coe State Park)

Mouse-over to see annotations. (Requires Javascript) Click to see high-res version.

Image Details:

Camera: Mofidied Canon Rebel XT (350D): Hutech Type I Filter Replacement
Mount: None
Scope: Canon EF 200mm f/2.8L II USM lens
Configuration: Prime Focus
Additional Optics: n/a (Prime)
Filter: None
Effective Focal Length: 200mm
Effective Focal Ratio: f/2.8
Exposure: 410 x 6sec @ ISO 200
Total Exposure: 0hrs, 41min
Date: 9/4/2007 10:30pm PDT
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: None
Guiding: None


  • IRIS: Dark subtraction, PIC to BMP Conversion
  • JimP: Flat field, White Balance, ASINH stretch
  • BMP2PNG: BMP to PNG conversion
  • Mencoder: PNG to AVI movie encoding
  • Photoshop: Image scale, JPG conversion

Image Description:

This is a photo and animation (5 MB) of what threatens to become one of the largest wildfires in Santa Clara County history, according to the San Jose Mercury News. The images were captured from my house in Saratoga, roughly 35miles west of Henry Coe State Park, where the fire is centered.

While not really an astrophoto per se, the acquisition and subsequent processing of these images use the exact same process I've been using for DSLR imaging of the universe, including calibration (dark subtraction, flat fielding) and subsequent processing in IRIS and home-brewed software tools. Note, for example, the complete absence of checkerboard “pattern noise” in the background, as well as a complete lack of vignetting. In addition, Coe is one of the sites frequented by Bay Area astronomers seeking dark skies.

The animation (5 MB) is a time lapse, consisting of 410 stills taken with the DSLR, each a 6 second exposure with 5 seconds between them for mirror lockup (to avoid vibration) and for time to save the image to compact flash. Total time span is about 1 hour and 15 minutes.

A higher resolution image is also available. The camera is looking almost due East in this picture, with San Jose between the camera and the fire, but off-camera to the left (North).