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Open Cluster M46 and Planetary Nebula NGC 2438

The two-day old waxing crescent Moon is seen with Earthshine in this high-dynamic-range (HDR) image.

Eight different exposures were composited together to capture the entire brightness range of both the brilliant directly-illuminated sunlit crescent portion as well as the dark side of the Moon illuminated by Earthshine - sunlight reflected off the Earth.

A 1/30th-second exposure at f/8 at ISO 400 was required for the crescent, and a 4-second exposure was required for the Earthshine. Other exposures, one-stop apart, were used to record detail across this entire brightness range.

The human eye is capable of viewing a scene with this much difference in brightness and seeing detail in both the bright and dark parts at the same time. However, a single photograph usually cannot capture this kind of range of contrast. With the HDR technique, different exposures can be used to record the all parts of the brightness range and produce an image that more closely approximates what the scene actually looked like to the eye.

Exposure Data
  • Lens: Astro-Physics 130EDT f/8 Triplet Apochromatic Refractor
  • Focal Length: 1,040 mm
  • Focal Ratio: f/8
  • Exposure: 1/30, 1/15, 1/8, 1/4, 1/2, 1, 2, and 4 second exposures
  • Mount: Losmandy GM100-EQ German Equatorial Mount
  • Guiding: Unguided
  • Camera: Modified Canon EOS 1000D (Digital Rebel XS) DSLR
  • Mode: Raw
  • ISO: 400
  • White Balance: Custom
  • In-Camera Noise Reduction: Off
  • Filter: None
  • Date: March 17, 2010
  • Start Time: 7:52 p.m. EDT
  • Location: Coyle Field, NJ
  • Calibration: None
  • Processing: HDR, adjusted and enhanced in Photoshop CS5





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