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On Thursday 29 March 2007 08:56, Terry Hill wrote: > > filters created from unexposed but developed film does a good job at > > filtering white light (as is used in the conversion of webcams to stop > > the white light spectrum). > > I've been meaning to do this for ages - http://www.hoagieshouse.com/IR/ > > Have you made one yet? The guide indicates to me the film should be > overexposed colour film - eg the places where the negative is black. Yes, several times. The website is my brother in laws - we dreamed up the idea a few Christmases ago and began experimenting with simply filtering the light with different things to see what would work. Geoff (the BiL) then dismantled a cheap webcam to discover that the filter within the camera which blocks IR is simply a square of tinted glass in many cases. The film needs to be exposed but developed. We found that on many negatives, there is a small area at the start which is usually exactly what you want. As you say, it looks totally black. Thats the stuff you want - generally we find two squares of this filter is ideal. The hardest problem is finding an IR light source to test it with - although of course a remote control works fine for that. Geoff has converted a digital camera for the same purpose, but I haven't got a spare one myself to hack up! Think he bought his on ebay and once it worked in IR he did some more hacking on it - fiddling with long lenses etc. Mark -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html