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IR Photography with the Sigma SD10

Removing the Hot Mirror

by Gisle Hannemyr

On the Sigma SD10, the IR blocking filter (hot mirror) can be removed in less than a minute. Without the hot mirror, the Sigma SD10 has an infrared sensitivity only one stop below visible light.

To "modify" a Sigma SD10 for infrared, you just remove its dust protector with a small screwdriver. The dust protector in the SD10 doubles as the IR-blocking hot mirror. It is an easy operation, and is described in the Sigma manual (see images below) - so ulike other hot mirror removals, doing it will not void the guarantee.

SD10: Loosen screw SD10: Remove assembly
Loosen screw Remove dust protector/hot mirror

Note: Unlike the Sigma SD10, the Sigma SD9 dust protector is not a hot mirror, so removing it will have no effect on IR sensitivity.

Usage notes

Below are some notes on using a Sigma SD10 for infrared photography, loosely based on my own experience and exchanges with Champa and Dominic Groß in various DPreview forums:

  1. Keep a screwdriver in the camera bag and a filter box to store the dust protector in. Whenever a scene suitable for IR show up, remove the dust protector/hot mirror as described in the SD10 manual.
  2. Use an infrared filter. The SD10 works fine above 780 nm (Wratten #87), but for an even stronger IR-effect, a filter with a 830 nm cutoff (Wratten #87C) can be used.
  3. The viewfinder will be dark, so you need to use an accessory viewfinder. Autofocus may still work, but if you have to resort to manual focus, make sure you apply the appopriate focus shift.
  4. Turn on the histogram during the review to check exposure.
  5. Use monochrome WB in Sigma Photo Pro (SPP) to process the shoots.

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