On Thu, 23 Aug 2001 05:17:52 -0400 (EDT), aladdintracy@webtv.net wrote:

>Do IR Filters realy work with video? Or do they just take the color out?
>From photos I've see on the net, I would think that if I veiwed a
>recorded tape on the TV set and adjusted the color to black and white, I
>would probably gt the same results. I never used a IR Filter because you
>need nightsight or very good sunlight from what I understand.

Video CCDs are very sensitive to infrared, but normally
there is an IR-blocking filter in front of the CCDs
in the camcorder making their IR sensitivity very low.
Adding an IR-pass filter blocks visible light and
further reduces sensitivity of the system to the point
where the widest lens stop and a slow shutter speed
would be needed in bright light to get an image - hardly
worth it. The "nightshot" feature is a switch that
mechanically removes the IR-blocking filter, giving a
"tooth-paste green" colored image of high sensitivity
and IR characteristics. Adding a no. 87 IR-pass filter
slightly enhances the effect (a simple and cheap red or
orange filter has almost as much effect, and a polarizer
can also enhance the image, as can shooting IR in B&W
mode). Add "super nightshot" (just a name for slow
shutter speeds), and the cameras can operate in VERY
low light (or no visible light, with an IR light
source added). Of greatest interest to me is being able
to shoot IR in daylight (for examples of this, see:
http://www.David-Ruether-Photography.com/ir.htm), but Sony got
nervous about reports of "seeing through clothes"
with this feature (it doesn't work...;-), and
unfortunately disabled daylight-IR ability by forcing
the aperture wide open and limiting the shutter to
1/60th when "nightshot" is engaged. This can be bypassed,
but with camcorders that have a sharp image with the
lens wide open (PC100/110/120-TRV20/30), one can add
crossed linear polarizers and a 4X ND filter to block
enough light to make good daylight exposures possible.
As for the "look" of IR (in B&W), it is generally
quite different from panchromatic B&W - clear skies
and water turn near-black, foliage and skin turn
near-white, car headlights flash (an effect that
caused some people to think they saw gunfire in
aerial IR footage shot at Waco...) - there is a
pleasant "other-world" effect that is, I think, far
more interesting in video than it is in stills.
Most people who see my IR landscape video work really
like it! ;-) BTW, the IR effect can make somewhat
transparent single-layers of open-weave cloth (like
speaker grille cloth), but don't bother aiming the
camera at people with other than "good" intentions,
since people normally wear multiple layers of cloth,
which are totally opaque even with IR viewing...;-).
Also, one wonders why Sony got nervous about leaving
the daytime-IR effect useable, but not about the
nighttime-IR effect...;-)