IR filter shenanigans

There’s a question we’ve been asked very frequently about the camera board. A number of you want to use it for night-time photography, and ask if we can remove the IR filter. Notably, London Zoo are planning to deploy the camera board and Pi in a number of camera traps in Africa, where they’ll be looking for nocturnal animals and for poachers. The problem is, we source the sensor/lens package as a sealed unit from Sunny, so we don’t have the option to remove the infra-red (IR) filter, which is sandwiched inside that unit. This causes trouble for those of you who want to take low-light pictures of wildlife, or for security or astronomy.

Over at Reading Hackspace, Gary Fletcher (also attached to London Zoo, and planning to use a Pi camera in his role at the Horniman Museum aquarium for detecting the night time spawning of corals, which he hopes to deploy in Guam in just over a month’s time) mailed us to ask about the filter. Eben didn’t hold out much hope for manual removal of the filter, but suggested that some very careful scalpel work might achieve results. If you attempt this, be aware that it’s not really a supported option, and that if you try you may break your camera board. (Gary, Barnaby and team did break the first board they attempted this with.) Also, be careful around IR sources if you’re playing with IR photography – the human eye doesn’t have a look-away or blink reflex associated with IR, and you can damage your eyes if you stare at a very bright IR light.

We think the results are worth it, though. Here’s some instruction and illustration from Reading Hackspace, with special thanks to Barnaby Shearer. First of all, here’s a howto video.

This video demonstrates IR pickup: you can watch the tip of a soldering iron change colour as it heats up.

Another demonstration, this time of night vision. The scene is illuminated with the IR from a television remote control.

Finally, here’s a demonstration of the pattern of light from a Kinect, filmed with the filter-less camera board.

The usual warnings apply, but if you do decide to try this yourself, we’d love to see the results. A huge thanks to Gary, Barnaby, and all at Reading Hackspace for being prepared to imperil a camera board, and for all the helpful video!

Edit to add: Gary has just left a comment below with more tips and instructions. Check it out if you’re planning to try this at home.