Slit Scan with the OM4 the “Coffee grinder”

I don’t like to waste things and in particular cameras. This Olympus OM4 had questionable electronics so was of otherwise little use. One thing about the OM4 though is that although it requires batteries and electronics for normal operation that isn’t true for bulb mode. With that in mind I set out to modify it into a slit scan camera. Before I go into that though here is a little description of what that is.

Normally the intention when capturing a picture is to record the entire scene in one exposure. With a slit scan camera what you are doing is recording the same small slice of space in front of the camera over time. You achieve this by moving the film behind a vertical aperture or ‘slit’. This is the principle behind finish line cameras.

To do this with the “Coffee Grinder” I replaced the rewind lever with a larger system that would allow me to crank in a smoother motion without shaking the camera. I also made a mask from some thin opaque instant film backing leaving approximately a 0.5mm slit for light to come through.

Loading the film is a matter of taking all the film out of the canister onto the take up spool. I did this by covering the lens with a cap and advancing the film all the way out one frame at a time.

Then in preparation for taking an exposure what you do is set the camera to Bulb mode, cock the shutter and press the rewind button. Now you are ready. For smooth even operation a tripod is a must.

When you want to capture something you press and hold the bulb button while cranking the lever in the rewind direction. As you are in a sense just capturing the same sliver of a scene over and over again if nothing changes then what you get is streaks like this.

It gets more interesting when something is moving in front of the camera during the exposure. Things that are moving from left to right are stretched over time and things that are moving right to left are shrunken all the while the background is the same so results in just streaks.

The March

Some things I learned from this experiment that will allow me to improve the next iteration. I ended up cranking too fast in most cases which used more film than was necessary and resulted in too much stretching of time. I compensated for this by squeezing the scanned images horizontally. If I am to slow the cranking then I will need to reduce the size of the slit or stop down the aperture more so I don’t over expose the film. Also as smoothly as I tried to crank you can see the vertical banding that results from variations in speed. Removing the human element and replacing it with a motor would be the best way to deal with that but considering that this was a one afternoon project I’m not unhappy with the results.


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