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How to Build Your Own Lens IR Filter

Generally, a camera picks up visible light as well as normally invisible infrared (IR) light. The natural infrared wavelengths are not noticeable in the final photograph unless the photographer places a specialized filter in the lens to single out this wavelength above all others. This results in a picture that displays the heat signatures, radiating in infrared light, of a scene. Commercial IR filters for cameras can cost thousands of dollars, which make IR photography prohibitively expensive for amateur and some professional photographers. You can make your own IR filter, although it will not create a flawless professional result, if that is required.

Things You'll Need

Unexposed slide film
Developing fees
Masking tape

Instructions

- 1
  Buy unexposed slide film. It doesn't matter whether this is expired or still in date, as it is the darkness and transparency of the film sheet that will stop the visible light wavelengths from entering the camera lens.
- 2
  Get the film developed without exposing it. This will make the film dark and suitable as a filter. E6 film is a suitable type and size 120 film is large enough to fit a variety of lenses.
- 3
  Cover the camera lens with the unexposed but developed film and attach it securely to the sides of the lens with masking tape. Do not attach the film directly to the lens as this can damage it.
- 4
  Take a picture with the film-covered lens. If the camera produces a picture that reflects an infrared heat pattern, the lens works.
- 5
  Dismantle the lens if the external IR filter placement does not work. Be aware, however, that this process could damage the equipment and should only be done with obsolete or very cheap equipment. Taking off the lens typically requires the removal of small screws. Some camera lenses, such as those found in webcams, contain tiny glass filters to block IR light from getting to the sensor mechanism. Typically, these filters are placed behind the lens and in front of the sensor and circuit board.
- 6
  Remove this IR blocker, reassemble the camera and place the homemade IR filter on the outside of the lens in the same manner as in the previous steps.

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