Digital Infrared

The best solution is to have a camera converted. This involves having the IR blocking filter removed and replaced with either plain glass ( for a full spectrum conversion ) or a filter of your choice. Popular filters are 550nm, 665nm, 720nm and 850nm. The 590nm and 665nm filters which cut off at a shorter wavelength will record some visible light as well as the IR and are used mainly to produce the false colour IR images. The 720.nm filter gives mainly a monochrome image with perhaps some blue in the sky and water, the 850nm filter gives a monochrome image similar to those from black and white infrared film. Having the filter inside the camera means that it is possible to see through the viewfinder and the camera can autofocus. As the camera is now fully sensitive to IR shutter speeds and apertures will be in the normal range, correction factors still need to be applied for accurate exposures.

With this type of conversion the range of filters available to use depends on which filter is fitted in the camera. If the 590nm filter is fitted it is possible use a 665nm, 720nm or 850nm on the lens to obtain the different effects available with these filters. However if the camera is fitted with 720nm filter only the 850nm could used on the lens as the 720nm filter in the camera would filter out the visible light being passed by either 590nm or 665nm filter and the false colour effects of these filters would be negated, the result would be just the same as 720nm filter alone. A larger range of filters is available with a full spectrum conversion. The best option for this type of conversion is a DSLR with live view or a mirroless camera. With a full spectrum conversion, in live view the autofocus and exposure are taken off the sensor, therefore the camera will autofocus and the exposure will be accurate and show exposure simulation on the viewing screen with any filter. Also using a colour correcting hot mirror filter on the lens allows a full spectrum camera to take normal pictures.

Since IR light looks red to digital camera sensors if the camera is just used with a daylight or automatic white balance all images would look very red. To achieve a correct white balance with IR it is necessary to set a custom white balance. For 720nm and 850nm filters this should be set using green foliage as the WB target as this reflects a lot of IR light. With the 590nm and 665nm filters it is usual to use a grey card for the target target as these filters also record some light in the visible spectrum. Unfortunately some camera models are incapable of setting a proper in camera WB in infrared because they were never meant to “see” IR light as they were designed for visible photography. I have used a Nikon D50, a Nikon D200 and I am currently using a Canon EOSM with a full spectrum conversion and I have not had any problems setting a Custom white balance with either of these cameras, I also believe that an IR custom white balance can be easily set with the Canon 450D. It may be worth a look on the lifepixel.com website as they did have list on there of cameras which would not set an IR custom white balance. With a custom white balance set jpeg files will be fine and can be further processed in photoshop. However, with raw files a correct custom white balance cannot be achieved in Adobe camera raw. Although Canon raw files will set an accurate white balance in canons digital Photo Professional and likewise Nikon raw files in Nikon capture. The way round this for Adobe camera raw is to download free from Adobe their DNG profile editor. To use this open your raw IR file in ACR, do not make any adjustments, select save and save the image as a DNG file. Then open this DNG file in the DNG profile editor and under the colour matrices tab adjust the white balance to a correct value using the sliders in the white balance calibration section. When you are satisfied with result save as a profile with the name of the IR filter used this will be saved under the camera calibration tab in ACR. Open an IR raw file made with this filter in ACR and select this profile which will give you a correct white balance.