A computer-controlled shutter for Polaroid packfilm cameras

[Georg] wanted to modify his old Polaroid land camera so he could have control over the exposure time. The resulting project is a neat hack, if we say so ourselves.

The stock electronics in Polaroid 100-series Packfilm cameras were a simple analog computer that integrates current through a light-sensitive resistor. This is a simple, low tech way to make sure the exposure time is correct. The usual mod would be to replace photoresistor with a potentiometer, but [Georg] had little success with this modification. After tearing the old hack out of the camera, [Georg] replaced the ancient electronics with a a PIC microcontroller, and is now able to control the shutter in increments down to 1/512th of a second.

Shutter timing is read by a PIC12F629 μC with a BCD encoder. [Georg] kept the shutter magnet setup, and also added a ‘BULB’ routine that holds the shutter open as long as the button is held down. The test photos are quite nice, even if from a 1960s Polaroid Land Camera. Check out the video of [Georg] running though the shutter settings after the break.

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StereoData Maker

So you got CHDK working on your camera, and the histograms, raw image files, variable shutter speeds and other added functions are amazing, but stereo imaging is what you really want. If you have two or more CHDK-ready cameras, it’s cheap and easy to run StereoData Maker, a system that synchronizes the shutter and flash of multiple cameras.

The first step in getting SDM to work is installing the software on your SD card. You’ll need to find the correct version for you camera; a list is available on the main SDM page. If you are running Windows XP or Vista, run the installer in the zip file. Otherwise, load the files on the SD card and run the installer directly from the camera. Then decide whether this will be the right or left camera and repeat the steps for your second camera.

Next, you’ll need to prepare a switch unit, essentially a set of synchronized USB remotes. There are many ready made commercial units available, but building one on your own shouldn’t be much trouble, and a few ideas are provided on the SDM instruction page.

You’re basically ready to start shooting stereo images, just take a few test shots to get used to it and to customize the configuration on the cameras.