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01-28-2010, 07:32 PM   #1
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Side effect of stabilisation?

I have a photo I took of a building in Tokyo with the blue moon of new year above it. I took the photo hand held. The building is quite sharp - yet the moon is elongated diagonally. How is this possible? I would have expected that either the whole image would be blurred or none would be blurred. Why would the moon'd image be different from that of the building?




Last edited by RobG; 01-28-2010 at 07:54 PM.
01-28-2010, 07:36 PM   #2
Damn Brit
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Loading up the picture would help.

Without seeing it I would say it has nothing to do with SR and is more than likely a case of over exposure.
01-28-2010, 07:51 PM   #3
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I'm going to throw an idea out here (and I've seen similar things happen with astrophotography)...

The moon was probably a fair bit brighter than the building.

If you got a little shake at some point during a long exposure, it could be sufficient to cause the brighter objects (i.e. moon) to blur, while the movement was too short to visible affect the lower lit objects.

I see similar things when doing astrophotography, where if I say bump the tripod during a long exposure, I get blurring of the brighter stars in the final image, while the weaker ones don't show any visible blurring.

e.g. if you have a 1/2 second exposure, and you for some reason got movement during 1/60 second, if the object is bright enough that 1/60 second will suffice for causing some smearing, while fainter objects won't record much light during that brief moment.

Hope that makes sense.
01-28-2010, 07:56 PM   #4
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QuoteOriginally posted by pingflood Quote
If you got a little shake at some point during a long exposure, it could be sufficient to cause the brighter objects (i.e. moon) to blur, while the movement was too short to visible affect the lower lit objects.
Ah, that makes sense. The stabilisation over the longer exposure made the building sharp but a brief bump registered on the image of the moon. Bizarre but I can see how that could happen.

01-28-2010, 07:57 PM   #5
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QuoteOriginally posted by RobG Quote
I have a photo I took of a building in Tokyo with the blue moon of new year above it. I took the photo hand held. The building is quite sharp - yet the moon is elongated diagonally. How is this possible? I would have expected that either the whole image would be blurred or none would be blurred. Why would the moon'd image be different from that of the building?
The moon "moves".
01-28-2010, 07:57 PM   #6
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QuoteOriginally posted by Damn Brit Quote
Loading up the picture would help.
Done

QuoteQuote:
Without seeing it I would say it has nothing to do with SR and is more than likely a case of over exposure.
I don't think so - over exposure might make the moon appear bigger but not elongated.
01-28-2010, 08:20 PM   #7
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It looks like what we in AP call a "foot and nose binary" -- I would guess that SR didn't kick in immediately and you got some blurring because of that.

Wheatfield: the moon does move, but unless the guy was shooting a multi-second exposure it wouldnt really be noticeable and since he was using SR I'm assuming it was no slower than 1/2-1 second.

If you shot in RAW, I'd be curious to see if you get any "ghosting" of the building if you really crank up the exposure in post processing... the moon's way way overexposed so even a 1/100 second or so delay before SR kicked in might've been enough.
01-29-2010, 12:23 AM   #8
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QuoteOriginally posted by RobG Quote


I don't think so - over exposure might make the moon appear bigger but not elongated.
I was confused because you said you hand held and yes it is possible to appear elongated with over exposure. All it takes is for one half to be slightly brighter than the other.

01-29-2010, 12:39 AM   #9
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How about a lens aberration?
The moon is close to the edge of the frame where some aberrations can be prominent.
01-29-2010, 08:00 AM   #10
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yeah i'd say its astigmatism effect of the lens - not of the sr....
01-29-2010, 05:39 PM   #11
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Distortion and Astigmatism

The top (as we see it) is blue and the bottom is green.

Does that tell us something, particularly about the lens? (It doesn't tell me anything because I'm pig ignorant - not having worked with anything optical since a classical physics class taken during the latter part of the Enlightenment.)
01-29-2010, 10:40 PM   #12
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Whats the shuttle speed on your picture? I would have thought if the shuttle is slow, the moon will "move", but your buildings stay.. so you get those effect instead.
01-29-2010, 10:59 PM   #13
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Don't forget that the movement of the camera is magnified as distance is increased. And buildings move also. The taller they are the more they sway. Most tall buildings actually have counterweights on the roof to counteract it but they still move.
01-30-2010, 01:24 AM   #14
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QuoteOriginally posted by mcjm78 Quote
Whats the shuttle speed on your picture? I would have thought if the shuttle is slow, the moon will "move", but your buildings stay.. so you get those effect instead.
From the exif data;

f2.8, 1/10s
Pentax K200D with SMC DA 35mm f2.8 macro limited.

Unless it was a long zoom, the movement of the moon due to the earth's rotation wouldn't be noticeable until a multi-second exposure. This was hand held (I was actually standing in the street so no time for tripods even if I'd had one).

I don't buy the suggestion that it's lens abberation as someone else suggested; there's no noticeable abberation elsewhere.

Thanks for all the suggestions!

Last edited by RobG; 02-01-2010 at 01:19 AM. Reason: corrected lens details
01-30-2010, 04:06 AM   #15
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It's easy to test it, take a similar shot once with SR, once without and compare. Whatever the reason though, the consensus seems to be that this phenomenon was optical, not mechanical.
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