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Old Mar 10, 2006, 10:32 PM   #1
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Hi folks,The following two photos were taken on a Canon 350D, with a Sigma 70-300mm APO DG macro lens. Both shots were taken ISO 100, focal length of 300mm, f 5.6. The first was taken with an exposure of 1 second; the other at 1/250 second. I'm curious to see if anyone's got an explanation for the artefact seen in the 1 second shot. I quite like it; it's just not what I was expecting! FWIW, I took a series of shots with the same settings except for exposure: this ranged from 1 second to 1/1250 second. The "second moon" was last seen at 1/8 second. Cheers,PaulĀ*!Cheers,Paul
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Old Mar 10, 2006, 10:33 PM   #2
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For some reason, only one file got up there; here's the second file. Paul
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Old Mar 12, 2006, 5:01 AM   #3
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Hi. My first posting. The artefact is a mirror image of the moon but at reduced brightness, caused by internal refraction in the lens. Obviously this only showed up with a dark background and a 1 second exposure. Regards Gary
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Old Mar 12, 2006, 5:56 AM   #4
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Internal reflection will show up as 'flare' with multiple images...

IMHO this could come either from the filter up front (if any) or are you shooting behind a window pane?
-> Clearly the moon is 180 degree out of phase and not on the same plane which can only resulted from a reflection :idea:
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Old Mar 12, 2006, 2:20 PM   #5
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Hi NHL -- you might have it! There is a UV filter on the front of the lens (and here was me thinking that I'd managed to document *everything*...). I was outside for shooting. Cheers,Paul
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Old Mar 12, 2006, 2:30 PM   #6
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Liegroupoid,

How do you like this lens? I like the price and less weight. Is it sharp, fast to focus? What do you lose by paying so little?

Are there other similar price and weight lenses which may be better quality by other manufacturers? Thanks!
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Old Mar 12, 2006, 8:17 PM   #7
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Harana, I like this lens: as I said in another thread, I'm more than happy with the output from it. With regard you your specific questions, the AF does hunt a little in very low light conditions, otherwise it's fine. I like the sharpness achieved with this lens. I recently took a photo which showed pronounced vignetting at 300mm -- this is the first time I've seen this in over a thousand shots with this lens (see attached file). What do I lose by paying so little? More like, what do I gain: marital harmony Cheers, Paul
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Old Mar 13, 2006, 12:52 AM   #8
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Liegroupoid, Thank you for the infomation. I find this forumveryhelpful. Yours and other members' responses have helped me immensely in understading whatwill be best suitedfor my interests in photography and, of course, my pocket book.
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