APOD: Sunrise, Moonrise (2011 Jan 06)

Comments and questions about the APOD on the main view screen.
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Chris Peterson
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Re: APOD: Sunrise, Moonrise (2011 Jan 06)

Post by Chris Peterson » Sat Jan 08, 2011 4:47 pm

NoelC wrote:
Chris Peterson wrote:Alright, it is almost always smaller near the horizon. <g>
Image
Exactly. Your image shows what the Sun looks like in most cases when it's near the horizon- quite a bit smaller in area than it is when higher.
Chris

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eaglekepr
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Re: APOD: Sunrise, Moonrise (2011 Jan 06)

Post by eaglekepr » Sat Jan 08, 2011 5:05 pm

Chris Peterson wrote:I suspect that the zoom lens shifted (or was misadjusted) slightly between exposures, resulting in the actual Sun images being made at something other than exactly the same focal lengths.
Agreed... although I wouldn't try to use an artistic compilation of manipulated images taken with an imprecise consumer kit lens (aka "cheap" Canon EF-S 18-55mm by the look of it) to make factual scientific judgments on measurements in any case :lol:

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Chris Peterson
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Re: APOD: Sunrise, Moonrise (2011 Jan 06)

Post by Chris Peterson » Sat Jan 08, 2011 5:16 pm

eaglekepr wrote:Agreed... although I wouldn't try to use an artistic compilation of manipulated images taken with an imprecise consumer kit lens (aka "cheap" Canon EF-S 18-55mm by the look of it) to make factual scientific judgments on measurements in any case :lol:
Right. Actually, this case is just the opposite: we know on solid scientific grounds that the Sun's apparent diameter isn't changing. We can therefore use the Sun as a scale reference, and make some deductions about the equipment and method used to produce the image. What we know about the Sun and atmospheric optics informs us about the image, not the other way around.
Chris

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