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Electronic Flash artifacts

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Bob Cole
Electronic Flash artifacts
on Aug 5, 2009 at 6:17:06 pm

When shooting a graduation ceremony with an EX3, I noticed that when a photographer set off an electronic flash, often only part of the video frame was brightened. This happened repeatedly. The result is a frame with two horizontally-demarcated sections, one with the characteristic overexposed flash look, the other normal.

Is there anything I could have done to make the whole frame light up or is this inherent to the design of the EX3?

Bob C

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Craig Seeman
Re: Electronic Flash artifacts
on Aug 5, 2009 at 6:25:01 pm

This is related to how the CMOS chips are scanned. Often referred to as "Rolling Shutter." The flash happened mid scan so part lands on one frame and part lands on the next.

While it's "different" that what one would get with CCD, I'm not sure if "different" automatically makes it worse. None of my clients has ever commented on it. I'm sure they notice it but I suspect they don't see it as any more annoying than a flash.

I've seen much debate over how the look is impacted by frame rate and shutter speed. They don't impact the scan rate of the chips themselves but can impact how the image looks on a given frame. Changing frame rate and shutter speed have other aesthetic impacts though that one has to consider.

BTW I've shot fireworks many times and there's no visible artifacts. The issue becomes obvious when the flash (or other strobe . . . like the flashing light of a police car bubble) fills most or all of the frame which makes the split scan more likely.

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Noah Kadner
Re: Electronic Flash artifacts
on Aug 5, 2009 at 7:19:13 pm

You'll see them if you really look for them, especially frame by frame, but the average layman wouldn't notice or care if they did.


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