On Thu, 23 Aug 2001 14:52:18 -0230, "Chris"
>"Neuman - Ruether"
>news:3b850de6.1972671@newsstand.cit.cornell.edu...
>> 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...;-)
>http://www.kaya-optics.com/products/overview.htm
>
>Not only do they sell the nessacary filters, but they also give instructions
>on how to "repair" modified sony's, and turn other, regular (Meaning with
>the IR blocking filters) CCD camera's into IR cameras.
Definitely not for the "faint-o'-heart" - I would not
disassemble *my* camcorder to do this...! ;-) Also,
their $138 filter is essentially a no. 87, which is
relatively cheap purchased as a Kodak gel (well under
$20, as I recall - and it can be cut to size to drop
in under a UV filter [and this filter is not really
needed, since a cheap red or orange filter will cut
out enough visible light to make the IR-effects
show]). The site also indicates wondrous things that
you can see as a result - but, as I point out above,
you *will* be disappointed if you believe this...! ;-)