Almost all digital cameras are sensitive to both visible light and infrared light. To prevent images to be contaminated with IR-light camera makers install an infrared blocking filter in front of the sensor in their cameras. The filter blocks out almost all IR-light but since it doesn’t filter out 100% of the IR light it is possible IR photographs with a normal digital camera. This is done by using another filter that blocks out as much visible light as possible but lets IR-light through and then shooting with long exposure time to let enough IR light though to go through the IR-blocking filter and be registered by the cameras sensor. The IR-images looks almost like a black and white shots and often has a ghostly feel to them. Since I like to experiment with what I have I decided to build my own IR filter using the magic substance Sugru (like play-dough that sets and becomes rubber in 24 hours) and some old film and I got some decent results I think.
Making the IR-filter
I started by making a frame for the filter that would fit on the camera lens of my Panasonic Lumix LX-3. This camera normally has no filter threads so I molded the frame with Sugru and let it set over night.
The material that make up the actual filter is old celluloid film that has been exposed to light and developed. The end bits of old rolls usually become exposed to light when you insert it in the camera. To block enough light is it not enough with just one layer, I used three layers.
After stacking the sheets of celluloid on top of each other I fixated them in place by applying some more Sugru, I also improved the fit of the filter on the camera lens with some more sugru on the camera side of the filter frame.
To prevent the Sugru from sticking to the camera lens during the fitting of the filter I used some wrap to create a barrier between them, I removed the wrap after I had finished fitting the filter to prevent the Sugru from sticking to it while setting.
The finished product does its job as can be seen on the spectrum photo below. It is by far not as good as a commercial IR filter but it is good enough to play around with and it is practically free. A big disadvantage with using celluloid as filter is that is is sensitive to moisture, at least one side of it is. I now have some permanent water drops engraved in my filter after dropping it in the snow, learning by doing.
jenslabs 
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