Re: Digital IR

[Andrew Davidhazy <ANDPPH@xxxxxxxxxxxxxxxxxx>]

> Can someone explain how people take IR photos digitally?

Holly,

There are various ways of doing this. Most electronic cameras that use CCD
sensors or "chips" are sensitive to infrared and manufacturers go to great
lengths to eliminate such "unwanted" sensitivity, typically using filters that
block the IR from reaching the sensor.

Some cameras (especially B&W surveilance cameras - some not CCD equipped but
still IR sensitive) , however, still exhibit high IR sensitivity and simply
placing a light blocking filter (a red 25, 29 or opaque 87, 87C, etc.) is all
that is required and if lots of IR is present they provide you with an image
that can then be "frame grabbed" and inputed to a computer where it is now a
"digital" image.
 
Another, "usual",ploy is to simply remove the IR barrier filter from in front
of the sensor and some people have done this with (sometimes)run-of-the-mill 
camcorder cameras. This is not often a very easy thing to do. At least one
camera line (Sony w/nightshot feature) has this feature built-in and makes the
process of imaging IR  rather easy. After taping in IR the images are again
frame grabbed and placed in a computer.

In a similar fashion, digital cameras often also exhibit at least residual IR
sensitivity and some people have taken advantage of this by shooting with the
digital cameras through a red or even IR filter and gotten passable results.
As a result of some controversy about this subject I tried out myself making IR
digital photos with an Agfa 1280 and the technique did work ... as long as the
sun was real bright!

Some high end cameras, both 35mm camera size as well as studio size, are
supplied with filters that operators place in front or behind the lens of the
system to remove IR for accurate color reproduction ... but some photographers
have simply not done that and placed a IR transmitting, light blocking, filter
in those positions and shot IR digitally directly. This is typically the
highest quality IR digital photography available. Also the most expensive.

I have been intrigued with making my own digital camera of sorts and recently
took the sensor out of a small, inexpensive, hand driven scanner and installed
it in the back of a "junk" mechanical SLR camera. I made a cable to connect the
sensor to the scanner assembly and have been making low-budget 360 degree
panoramic IR digital photographs for a few days now. 

I don't believe this is a new thing or application or endeavor but it was new
for me!
                                                              
regards,

Andy  o o  0 0 o . o  Davidhazy, Imaging and Photo Tech
       \/\/\/\/\/\/          http://www.rit.edu/~andpph
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