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Old December 3rd, 2003, 05:34 PM   #1
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Big Iron - Self-healing CCDs - sort of

If your large Sony has a bright pixel, Sony recommends you black balance the camera 3-6 times. This usually fixes the problem or dims the pixel quite a bit.

Since these cameras get quite warm if the've run for several hours, it pays to black balance after they get up to temperature anyway.
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Old December 3rd, 2003, 10:55 PM   #2
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Interesting. Hadn't thought of that, that temperature would affect settings.
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Old December 3rd, 2003, 11:13 PM   #3
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Especially in Ukiah in the summer!

Sony states that whenever significant temperature changes occur in the operating environment of the large cameras that the operator Black Balance them. I think that one has to wait until the internal temperature stabilizes.

BTW, I had a viewfinder on an EVW-300 go up in smoke because the summer sun raised the internal temp too high. I now use an umbrella or other sun shade when the camera will be in direct sunlight in hot weather.
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Old December 4th, 2003, 05:13 AM   #4
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Some cameras, especially those with FIT CCD's use a peltier element to help keep the chip cooler. Heat is one of the biggest causes of noise in the signal.
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Old December 4th, 2003, 09:48 AM   #5
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RE: Heat is one of the biggest causes of noise in the signal

Yeah - heat is a major problem, so much so that big (mirror diameters measured in meters) telescopes (I work for a bunch of astronomers in my day job) use liquid nitrogen to cool their CCDs so they can get the cleanest images out of them (exposure times in the hours at times to get views into deep space).
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Old December 4th, 2003, 06:47 PM   #6
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I've thought about using a group of Peltier junctions to cool an air stream and direct that onto the camera. The killer is always the undercooled theatre in the summer and a dark production.

It is quite possible to get to an external temperature in the summer that prevents one from operating any video camera.

Ice packs for cameras? Why not?
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Old December 4th, 2003, 08:45 PM   #7
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As far as I know, Peltier devices make one side hot and the other side cold. You put them in contact with whatever needs to be cooled and the Peltier device will draw heat out faster, but you still need some way of removing that heat. This usually involves moving air, water, or some other coolant over the Peltier device.

What I don't get is how you would cool a stream of air using Peltier cooling.... you're just making the air cooler and warmer.
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Old December 5th, 2003, 12:36 PM   #8
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The peltier junction doesn't have to directly contact a physically solid object to cool it. That side of the junction could have radiator fins attached to it over which you pass air, thereby cooling it.

You could split the stream of air from a fan and have one side supply the air stream for chilling and the other stream for removing heat from the Peltier device.
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