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Author Topic: Motion blur vs. camera shake vs. focus error  (Read 2517 times)
BobTrips
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« on: August 07, 2003, 12:57:26 AM »
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Well, there should be something in the frame that isn't a jumping girl.  A tree, a chair, a rock, something....

Look to see if it's in focus and/or if it's moving.  (In the latter case you, perhaps, photographed an earthquake - or a large mass of jumping girls. ;O)
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Eric Anderson
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« Reply #1 on: August 07, 2003, 10:06:05 PM »
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There's actually very little else in the scene, it was taken against a bright pink stucco wall, with the stucco small enough that it's at the resolution limit of the camera, and a little bit of base-board.  I suspect that X-Re was partially correct that I may have been slightly following the jumping, the base board looks about half a pixel more blurred than in the posed shot.  I'll have to think about how to avoid doing that in the future.  Any suggestions?

I also hadn't realized how little depth of field I had to keep the circle of confusion within a half pixel.   My calculations say that I only had 1.74 feet of depth of field for that level of accuracy, which is pretty tight given there were two layers of the girls. I cared about the high level of detail because I printed it at about 30" x 70" which does an amazing job at showing every possible flaw in the original image.

Thanks for the help.
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Eric Anderson
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« Reply #2 on: August 07, 2003, 12:43:56 AM »
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I got a chance to photograph a bunch of young girls for a technology camp, and I thought it would be nice to make a nice poster for them of a group picture. I got the standard posed group shot, but I was so amused at watching them follow directions (I don't think I was nearly so well behaved when I was that age), I asked if I could get a picture of them jumping up and down.

From an aesthetic perspective, the jumping shots are much better, everyone is smiling more, they look less serious and more like they are having fun. From a technical perspective the jumping shots are much worse, at 100% they look just a little blurry.

The two pictures were with the canon 16-35mm zoom on a D60 both at 1/125 s, F4, ISO 400; the posed shot at 17mm, the jumping at 16mm.

I'm trying to figure out whether I just got motion blur (I did ask them to jump up and down), it I just screwed up and wiggled the camera while I took the picture, or if I screwed up and got the focus wrong somehow.

What should I be looking for to tell the difference between these three possibilities?

Thanks,
   -Eric
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X-Re
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« Reply #3 on: August 07, 2003, 08:58:27 AM »
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The two pictures were with the canon 16-35mm zoom on a D60 both at 1/125 s, F4, ISO 400; the posed shot at 17mm, the jumping at 16mm.
1/125 might not have been quite quick enough, depending on how vigorously they were jumping - Bob's suggestion should at least tell you if you had the focus right, or not. There's gotta be *something* in the frame in the same area of focus that should tell you whether or not you had the focus right and/or held the camera steady enough.

     At 1/125 and 16mm, you should've been able to avoid normal camera shake effects (at least, by the 1/focal length rule) - of course, if you were "following" along with the jumping....
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