by Rolland Elliot
I had time during the holidays to disassemble my JVC GRDV1 digital camcorder. It's been eating up tapes towards the end ocassionally, so I didn't feel that bad if I were to break it while experimenting on it.
This camcorder is very small (about the size of a small paperback novel) and is sensitive to IR light, but only to a very slight degree. One has to set the camcorder to it's highest gain up level and also set the shutter speed to 1/4 of a second, which gives moving objects a very blurry look (kind of neat, but it gets old quick). In addition the camcorder needs bright sunlight to record IR light.
After fiddling with the camcorder for a long time, I managed to get to the heart of the machine, the CCD (it's the sensor which actually records the light, I think it stands for Charged Coupled Device), After removing the CCD from the lens assembly, I found exactly what I wanted: a small blue green IR blocking filter. This filter is quite a bit darker than the IR blocking filter made by B&W filter company in Germany.
Anyways, I removed the IR blocking filter and reassembled the camcorder. Unfortunately, I couldn't get the camcorder to focus. I immediately remembered that a focus correction is needed for IR light. So I again disassembled the camcorder and added a small paper spacer between the lens assembly and the CCD; I thought IR light focuses farther away than visible light so I thought I would need to move the CCD farther back from the lens. After putting the camcorder back together a second time, it still wouldn't focus properly.
So I opened it up a 3rd time and took out the paper spacer (about 0.5mm thick) and I also REMOVED an aluminum spacer in the camcorder to make the CCD about 1 mm closer to the lens. Then I put the camcorder back together for a third time ( I was getting pretty good at taking it apart by now). Focusing worked great! Finally! It still seems to me that the CCD should have been moved farther away, perhaps someone can explain IR focusing correction to me so I understand it better.
By removing the IR blocking filter the camcorder works great now for IR movie making. I set it to sepia or black and white mode with an 87 filter over the lens and I can easily record under normal light levels (for example inside using a 60W tungsten light bulb).
I realize that Sony makes NIGHT SHOT camcorders with IR sensitivity, but I always thought the green tint made these IR pictures rather ugly. It is really neat to preview an IR scene in Sepia tone using my camcorder. I spent a couple of days just looking around stuff in my house; here are some surprising/interesting observations:
The neat thing about this experiment, is that these digital camcorders can be had on ebay for around $500 dollars. The sony digital camcorders with night shot mode all cost over $1000. So one can save a lot of money.
The down side is that one has to dedicate the camcorder to IR film making since the IR blocking filter is not easily removed and reattached and the postion of the CCD has to be altered.
If you try this conversion method yourself please let me know.
Last Updated: Saturday, January 29, 2000
Part of the Infrared FAQ located at CoCam Photo.