March 8, 2006

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Two to One

Crescent and earthlight
image by Pete Lawrence

Pete Lawrence writes: I’ve been trying to get a good shot of the crescent Moon showing Earthshine for ages but have always failed due to the extreme dynamic range required - something the human eye manages exquisitely of course. The problem is that a shot correctly exposed to show the Earthshine will overexpose the crescent. This causes the terminator to expand into the dark half of the Moon. Matching a crescent shot to an Earthshine shot is therefore very difficult indeed. However, if you take the shots a few days apart - i.e. Earthshine on one day and Crescent a couple of days later, you have a bit of overlap to play with and can finally merge the two images together to create a composite that almost resembles what you can see visually through a small telescope. Well, it works for me!

Chuck Wood

Technical Details:
March 1 (left) and 4 (middle), 2006. Skywatcher 80ED Pro + Meade 0.63x focal reducer. Camera - Canon 20Da DSLR. Exposures - Earthshine 1/2s @ ISO1600, Crescent 1/1600s @ ISO800. Camera sensitivity was kept high as the telescope was undriven, mounted on a standard photographer’s tripod. The star to the right of the Moon is TYC2-1641-1, a mag +6.2 star in Pisces. CAW note: You might have to tip your monitor to see the right image properly illuminated - I do.

Yesterday's LPOD: On the Limb Again

Tomorrow's LPOD: Unbelievable Image


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