I recently learned that almost all digital cameras can actually see infra-red light. You can easily prove this to yourself by pressing buttons on your remote control while pointing it at a digital camera. For example, here is my remote control:

Animated gif of a remote control emitting IR light
Animated gif of a remote control emitting IR light

This suggests that given a suitable filter it would be possible to do IR photography with a normal digital camera! Luckily most houses do contain such a thing in the form of the negatives that used to be supplied with developed photos.  At the end of the negatives there is often a small black section. This is film that has been completely exposed and then developed.

Image of over-exposed film
Image of over-exposed film

This bit of the negative blocks out almost all visible light, but lets through IR. To completely block visible light you need two layers of this stuff, which you can then sellotape onto the front of a camera to create a cheap IR viewing device!

Image of over-exposed film taped to the front of a camera
Image of over-exposed film taped to the front of a camera

I found that in order to get good photographs the camera needed long exposure times (and therefore needed to be supported on a solid base to avoid blurring. Foliage, in particular, looks ghostly since leaves reflect strongly in the IR. Here are a few of my pictures:

IR photograph from my garden IR photograph from my garden IR photograph from my garden

Unfortunately light was slipping in from both sides of the filter and I didn’t notice this until it was too late!

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