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Old July 23rd, 2004, 10:02 AM   #1
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Need for IR filtration

I'm going to be shooting soon at a hot spring area and in a slightly warm volcano crater. During the autumn I'll also shoot around a campfire.

Do you think I need infrared filtration for my camcorder?

I allready have an UV+IR combo, but I've just upgraded to larger filter size (to allow stacking of two-three filters). Should I get a larger UV(0) filter or a larger UV(0)+IR combo?

They want to sell me a plain UV(0) filter. Because "digital cameras allready compensate for IR and thus there is no need to filter it anymore". Is that true? I'm a bit skeptic. Sales people very seldom know...
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Old July 23rd, 2004, 11:28 AM   #2
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I cannot really answer your question well, but at least chip in with a little bit of info. Video cameras are definately sensitive to IR. I use mine to troubleshoot IR based remote controls. If they work, the signal shows up as bright white on my Canon XM2 anyway.

Thus I figure that IR filtering might be of interest if you are shooting molten lava or something like that, but if you shoot stuff at pretty much ambient temperature, I cannot really see why an IR filter would be needed.

Remember that IR radiation frequency depends solely on the surface temperature of the object in question.

Hope that was useful.
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Old July 23rd, 2004, 02:08 PM   #3
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Cameras have an IR filter built in. It is normally a small piece of bulk-dyed blue glass.

Night shot is created by removing the IR filter.

Silicon-based detectors have much more sensitivity to IR than they do to visible light. The sensitivity curve has a peak right beyond the red end of the visible spectrum.
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Old July 23rd, 2004, 02:47 PM   #4
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...and where is the limit?

So modern camcorders do not need IR filtration in casual shooting situations like boiling water, bright sunshine etc?

How effective is the built-in IR filtration? If I can sense the direction of the heat radiation with my hand, then will the built-in filtration be effective enough? Maybe I should protect the lens and the rest of the filters?

I guess that after a certain point some added protection would be good and finally stepping back and zooming in might help too.
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Old July 24th, 2004, 12:27 PM   #5
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Re: ...and where is the limit?

<<<-- Originally posted by Ralf Strandell : So modern camcorders do not need IR filtration in casual shooting situations like boiling water, bright sunshine etc?
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Correct
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How effective is the built-in IR filtration? If I can sense the direction of the heat radiation with my hand, then will the built-in filtration be effective enough? Maybe I should protect the lens and the rest of the filters?
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It would help if you were imaging an iron foundry, perhaps, or arc welding. I've done both without additional filtering. Remember, the CCD turns the IR into visibile light in the viewfinder and on the tape.
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I guess that after a certain point some added protection would be good and finally stepping back and zooming in might help too.
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Although the focus point for IR is different than that for visible light and therefore the IR is somewhat out of focus, the bulk filter in the camera does a pretty good job.
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-->>>
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Old July 24th, 2004, 12:33 PM   #6
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Quote:
Although the focus point for IR is different than that for visible light and therefore the IR is somewhat out of focus, the bulk filter in the camera does a pretty good job.
The Depth of Field will cover most focusing errors unless your doing a lot of close-ups.
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Old July 25th, 2004, 02:48 PM   #7
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Thanks. A lot of money saved :)
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