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Old 28-08-2007, 12:12 PM
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Geoff45 (Geoff)
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Join Date: Jul 2006
Location: Sydney
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Quote:
Originally Posted by robin View Post
Assuming you're shooting on manual, then at 10 seconds, a exposure using f4 will definetely show more detail tahn a 10 second f16 exp.
I jumped in there without thinking too carefully.
You are right of course, because with the f16 exposure, the lens gets stopped down, so it has a smaller aperture than at f4. However the point I was trying to make it is the aperture that makes the difference, not the f ratio. A 50mm diameter lens at f4 will show the same limiting magnitude as a 50mm diameter lens at f16 for the same exposure.
Geoff
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