Resolution with Infrared


Today’s Question: If I have a camera body which has been converted to infrared capture and the sensor filter that was installed allows only black & white. Am I only getting use of 1/3 of the RGB pixel sites? If so, would I be better off converting a camera body with an overall resolution of 45 megapixels or getting an infrared (IR) filter conversion that allowed color IR for a 24-megapixel body?

Tim’s Quick Answer: You are indeed getting the full resolution of your image sensor when a camera is converted for digital infrared. The only thing that is changing is the range of light wavelengths that are recorded by the image sensor.

More Detail: Converting a digital camera to infrared capture generally involves two steps. The first is to remove the infrared cutoff filter that is installed in front of the actual image sensor on most cameras. This filter ensures that the sensor will not record infrared light, which could cause artifacts and other issues with a color photo. In other word, the camera is only able to capture light within the visible spectrum based on human vision.

Once the infrared cutoff filter is removed, the image sensor is capable of capturing light within the visible spectrum as well as the infrared spectrum. For infrared photography, you generally don’t want the visible spectrum included in your captures. Therefore, an infrared filter needs to be added for infrared photography.

Some infrared conversions include the addition of an infrared filter to the front of the image sensor, so that the camera is only capable of infrared photography. Alternately, that infrared filter might be left off, which would then require that you use an infrared filter on your lens in order to capture infrared photos. The benefit of the latter approach is that you could use the camera for both color and infrared photography.

As noted above, however, all of the pixels (photo sites) on the image sensor are still being used to capture the infrared information. Therefore, you should select a camera for infrared conversion based on the resolution you want available for the final file size. If you’ll be producing large prints, for example, you’ll want to opt for a camera with a relatively high resolution, all other things being even.