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After a few unsuccesful attempts to modify an old camera for infrared photography, I modified one of the two cheap cameras ($40 USD) that I’ve got some time ago. Those cameras are cheap and tiny, usually came embedded inside pens or keychains.
Due to their size it is quite common to modify or attach those cameras to a variety of places; think, for example, to attach the camera to ballons for aerial video, radio controlled planes, helicopters or other vehicules, or seal it inside an empty bottle for underwater photography, just to mention some random uses that came to mind.
It was on a RC forum thread where I first read about removing the infrared filter in those cameras, along with a lot of useful information.
The infrared filter is a thin circular element located on the rear of the lens. It was needed to carefully remove the glue around lens thread, but the overall process of removing the filter was much easier than expected, specially in comparison with any other camera I’ve tried before. Colors are distorted without its infrared filter, but in return it recieves more light, sensitivity improves, and it can be used as a “night vision” camera.
Once assembled and refocused, the first test was quite simple: let’s see the infrared light of a remote controller. The modified camera captures the light, while it is invisible to the other (as our eyes).
Next step was to block the entire visible spectrum, in order to capture infrared exclusively; that is, the inverse effect than the one performed by camera’s internal infrared block filter. I’ve used a filter designed for infrared photography, a piece of glass that looks black and completely opaque to our eyes, but not to the modified camera which can see through it.
The quality of the pictures straight from the camera is far from great. I’ve done the following:
- Recorded a video (1280×720), saved several frames, selected the center area of each frame to avoid the (quite noticeable) vignetting and blurring in the corners.
- Constructed a large panorama using all pieces.
- Applied a heavy noise reduction algorithm. Images loose detail, but noise levels were very high and ugly in the originals. As a side effect, the image enhances its artistic painting appearance, not so bad after all.
The original has a red or pink tone because the filter allows some deep red to pass through it. A deeper infrared filter should produce black and white images and only purely invisible light would be recorded, supposing that camera’s automatic white balance won’t become crazy, this is something I want to test later.
A common effect for infrared photography is to switch red and blue channels (if the filter allows some red to pass), or just modify color channels and give a fake set of new colors to the image.
Infrared photos tend to look surrealistic. We normally can’t see the infrared light reflected by things, hence the strange appearance. Sky becomes dark (blue is easily removed by the filter), clouds are bright and prominent; green trees and grass reflect a lot of infrared light and become very bright, while dry plants remain darker.
Unless otherwise stated, articles and their accompanying pictures are licensed under a Creative Commons Attribution 3.0 Spain License.
Roberto Gordo Saez
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