Tuesday, 26 July 2016

Infrared Video in Daylight using Sony Night Shot

Sony’s infrared NIGHT SHOT setting on their camcorders is useful for nocturnal wildlife forays, both for the wildlife itself when a visible light source cannot be used and for videoing cutaways of the watchers and drivers in the pitch dark. It is said to operate by moving the filter from the sensor thereby allowing near infrared and infrared wavelengths to be recorded. I wondered if it would be possible to use Night Shot in daylight to turn the camcorder (AX33) into an infrared camera by putting suitable cutoff filters over the lens.

Unfortunately, life is not that simple. Even with an 850 nm IR filter, there was massive overexposure on the Auto setting—the only setting permitted since in Night Shot mode manual exposure adjustment is blocked. So I started stacking neutral density filters over the 850 filter. Eventually with an ND8 plus ND4 (i.e. 5 stops) I could get a reasonably exposed image even in bright sunlight. I return to this set up below.

I also tried a 720 nm filter to see if I could generate faux colour infrared footage. Using the technique in Final Cut Pro X I have used with my 720 nm infrared-modified Nikon D7100, I could get a weak blue in the sky but nothing really worthwhile.

In trying to find out whether or not anybody had attempted to use Night Shot by day I came across a small Flickr group. Members of that have used a 2003 model Sony still camera (DSC-V1) which has Night Shot. Again an IR filter plus ND filters were the answer.

The original footage has the usual weak green hue. I did a simple black-and-white conversion. Noise, always a problem with infrared photography using cameras with small sensors, was evident. Therefore, I used Neat Video for noise reduction but there is a downside in that rendering times are increased markedly—very markedly.

To try the set-up out I tried a few hand-held shots in the village. You will see from the footage that at the shorter focal lengths there was peripheral unsharpness. I do not know the cause. At longer focal lengths, however, that fuzziness disappeared.

While not as convenient or versatile as a modern infrared-converted DSLR, the use of Night Shot does provide owners of Sony camcorders with the capability of taking infrared footage with the simple addition of cheap filters.