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If you're still curious, PM me an address I can e-mail a sketch to. |
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Another way of thinking of it is to think of what happens to the circle of confusion of an out of focus point source as you obstruct half the lens. One half goes away, so the nett result is the remainder is smaller and it's AVERAGE position is shifted relative to the unobstructed image. |
I think the effect is not totally dissimilar to crescent shadows during a solar eclipse, in which case the edge of the moon causes a lensing effect on sunlight.
http://www.astrospace.co.uk/gallery/...-crescents.jpg The bokeh is essentially distorted back in to (or towards) focus as it bends around the edge of the foreground object, atleast thats how I like to think about it. Particles... Waves... magic? ;0) Dave. |
What effect exactly are you all looking at? The only thing I see is a brief flash which could be attributed to the taxi turning slightly and having something reflect off its side - a few frames later it's clear the taxi is moving.
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I guess you and I have both very similar concept, but I also guess that you and me are trying to explain the same thing in a different way. One more thing I wan't to say is that the DOF and the aperture relationship is also based on the diffraction. The 'ray tracing theory' has nothing to say to this relationship. |
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Hope you don't mind me posting the grab Kaku !? |
Thanks Dave - yes, it's the difference between this frame and the one before that best demonstrates what's being referred to. Going back a frame, the unobscured "89" is still out of focus, but the now partly obscured "39" is sharper and darker.
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The sharpening effect on the 39 (partial bokeh) seems to me to be caused by the foreground 'man with bag' object as it moves past, almost as a halo effect. I'd call this diffraction = light bending around the edge of an object.
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My bad!
David and Serena, I'm sorry, I was wrong.
I re-tested it with my cams, and I realized that the image at the focus does not move. Only the images out-of-focus moves with the obstacle moving. Maybe the 'diffraction model' can precisely describe these, but now I agree with the David's explanation. It's enough to explain all these. Thanks. |
Posted this on another thread but applicable here. imho
I used to use an A1U and it had "Rolling Shutter" I looked for the footage but was not able to find it. Simulate the footage by selecting the highest shutter speed, 1/10,000 for A1U. Drive down the interstate in the fast lane at or just above the speed limit, 75MPH or so. Frame the oncoming traffic fast lane perpendicular to the flow of traffic. A box truck or semi-trailer would be noticeably slanted. I found it disturbing. Would be nice to see someone with an EX1 do this trick. Maybe shooting out the window of the driver's side backseat would be wise. |
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