Difference between revisions of "March 8, 2006"

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(Created page with "__NOTOC__ =Two To One= <div class="post" id="post-132"> <div class="storycontent"> <p>Crescent and earthlight<br /> <em>image by [mailto:pete.l...")
 
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<p>[[File:LPOD-Mar8.jpg|Crescent and earthlight]]<br />
 
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<p>[[File:LPOD-Mar8.jpg|Crescent and earthlight]]<br />
 
 
<em>image by [mailto:pete.lawrence@digitalsky.org.uk  Pete Lawrence]</em></p>
 
<em>image by [mailto:pete.lawrence@digitalsky.org.uk  Pete Lawrence]</em></p>
 
<p>Pete Lawrence writes: <i>I&#8217;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!</i></p>
 
<p>Pete Lawrence writes: <i>I&#8217;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!</i></p>
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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&#8217;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.</p>
 
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&#8217;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.</p>
 
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===COMMENTS?===  
 
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Revision as of 17:35, 4 January 2015

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.

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