It is easy to rely on the ratings marked on different tools, whether it is a power supply, scale, or*speedometer. However calibration is essential for any part that is relied upon either professionally or for a hobby. [Jeremy] wanted to see if his Lomography*camera shutter really was only open for 1/100ths of a second when set to that. In order to test his rig, he set up an LED on one side of the shutter, and a high speed phototransistor to gauge the time spent open, using an*oscilloscope*to measure the time the reference point was pulled low. In his case, when the camera was set to 1/100, the shutter was actually open for closer to 1/150th of a second (the mean was 1/148ths of a second, with a standard deviation of 417 uSecs). This difference can make a large difference in picture brightness.
Be sure to check his blog for more pictures of the setup, as well as some useful part references and circuit diagrams.
Filed under: digital cameras hacks, peripherals hacks
