CHOOSING A CAMERA FOR INFRARED CONVERSION
Updated: Aug 5, 2021
What is camera conversion?
Our regular camera is equipped with a filter in front of it's sensor, which cuts all infrared and ultraviolet radiation and allows only visible spectrum of light to reach the sensor. Removing this filter allows the sensor to record infrared radiation as well as ultraviolet radiation, in addition to visible spectrum of light. This modification is called as 'Full spectrum conversion".
This filter, also called as hot mirror, can be replaced with a filter which allows only infrared light to reach the sensor, and cuts all other radiation. Such conversion is called Infrared conversion.
Such modification makes infrared photography easier, but conversion itself has it's own problems. These problems vary depending upon types of cameras.
1) The cheapest option is conversion of 'point and shoot' cameras. They have single sensor, used for making images and for focusing as well. Even though most infrared filters are opaque for naked eyes, when they are fitted in front of the sensor, it is possible to compose, focus and view the actual image in electronic viewfinder and also on the back screen. Such cameras are very small and easy to carry around.
The problems with such small cameras is the small sensor and inability to add filters in front of the lens. Infrared images are inherently more noisy than normal images. Small sensors make this problem even worse. At the same time, small sensors tend to make images less colorful. Usually these cameras have fixed lenses, and most of the times the lenses do not have filter threads, making addition of different filters impossible.
2) Next type is DSLR cameras which are known for the ultimate image quality. Bigger the sensor, better the image quality. In the past these were the most preferred cameras for infrared conversion. They work flawlessly with the replaced infrared filters.
Problem starts when additional filter is attached in front of the lens. Since infrared filters are totally opaque to the naked eyes, nothing can be seen through the optical viewfinder. The solution is using live-view mode. The actual image that is going to be recorded can be seen on the camera's back screen. However, it is not very convenient when using camera outdoors in bright sunlight.
There is another problem. These cameras use two sensors. One for creating image and another for focusing. Infrared light focuses differently than normal light. Therefore, focus adjustment becomes a necessary part of infrared conversion and amount of focus adjustment depends upon the lens being used.
3) The most convenient cameras for conversion today are mirrorless cameras. They come with APS-C size sensors as well as full-frame sensors, therefore they can deliver excellent image quality. There is only one sensor, both for making the image and focusing, so no focus adjustment is required. It is very easy to add additional filters and easy to compose through electronic viewfinder. They are small and compact, so it is very easy to carry them around. Therefore, mirrorless cameras are highly recommended for infrared conversion, particularly if you are not tied with any DSLR system.