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Old Feb 13, 2005, 10:45 PM   #1
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I'm just getting started with studio strobes, and took this picture earlier tonight. In the top left corner of the picture, you can see there's a bright cirle that I can't account for. Could this be a reflection off the CCD onto the rear element of the lens?

I'm using Canon's EOS 20D with the 17-85mm zoom at f8.0, ISO100 and 1/125s. Camera was straight on at about 8' away, and the strobes were at 45 degree angles, about 5' away from the backdrop. Both strobes, Photogenic AK320's, were at 1/4 power, shooting into white umbrellas (no reflectors) bouncing light back onto the background.



There is also a bigger view here if you want.
http://dev.mdmiller.com/gallery/mill...50213/img_8493

Speaking of backdrops ... what's the best way to keep them? Iron them smooth and somehow try to keep them from getting wrinkled, or wad them up in a duffle bag so they're evenly wrinkled?
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Old Feb 16, 2005, 9:08 PM   #2
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Did you use a lens shade?

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Old Feb 16, 2005, 9:23 PM   #3
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No. In fact, I don't have a shade for either of my shorter lenses. The 70-200ISL USM came with a shade, but I don't remember getting one for the 17-85, and I know my 50 f/1.4 didn't.

You think that could be it?

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Old Feb 17, 2005, 1:21 PM   #4
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The spot is lens flare caused by light reflecting off of your front glass. You can buy rubber aftermarket lens shades that will help eliminate it. You can also eliminate most of it by making sure the lights are not aimed towards the front of the camera.
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Old Feb 18, 2005, 6:57 PM   #5
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The 17-85 doesn't come with a hood, you have to buy it seperate.
You can buy an aftermarket one like kalypso said. Or if you want to buy one from Canon, the model number is: EW-73B

That should get rid of the spot, unless you have the lights pointed directly into the lens.

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Old Mar 16, 2005, 2:56 AM   #6
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Is this spot reproducable under different conditions. Shoot a blank wall with your lights definately aimed away from your camera. Use various f stops. If you have dust on your sensor you will see it as out of focus circles. Remember your sensor is small so the individual sensors are microscopic. Dust on/near these sensors looks huge in relation to the size of these sensors.

Another possibility: there was a bug or dust in the air. When the strobes popped this object was illuminated but since it was not near your background it appears way out of focus. Of course, this is not reproducable. Your tests will just show the blank wall.

Good luck.

Terry Thomas

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Old Mar 22, 2005, 9:04 PM   #7
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I have a Sony p150 and it had the same problem. I sent it back to Sony. I just received it back late last week. They did not write what the problem was though. It is gone. I will call them tomorrow and ask them and then reply. I usually saw this on my camera when there was little moe light than just indoors. Aiming the camera at the lights. Outside was most noticable and seemed worse wen I zoomed.

Rob




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Old Mar 24, 2005, 1:00 PM   #8
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I finally reached Sony. The CCD block had a small piece of dust on it. She blew it off and problem is gone. With you having a dslr you should be able to clean that without sending it back to mfg? Thatmaybe it. I read that the ccd sensor is prone to atracting dust. That is why Olympus incorporated a shaking device into their evolt 300 camera.

Good luck.

Rob


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Old Apr 9, 2005, 7:06 AM   #9
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yep, its important to cover up the body with a cap, or even better leave a lens on. the guy at the local camera shop showed me a good idea, when changing lens, aim the camera downwards so that no dust particals get into it.
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