Automated testing of focal plane shutters

In this video I show you how I test the shutter speeds of my old analog cameras for accuracy with a DSLR. This method also allows you to see shutter bounce, shutter capping and uneven shutter speed.



After I do a series of exposures on all shutter speeds, the resulting images look something like this:

I then process these files with a Photoshop action which does the following:

• cut out a part of the center of the image
• apply a gaussian blur with a high radius to the cut out image
• reduce the resolution and save the image

After these steps, I use the eyedropper tool in Photoshop on the thumbnails of the resulting images to quickly compare the luminosity between the reference images and the test images.

I believe this is much more accurate than using photodiodes or photodetectors. When you use a photodiode on a shutter slit width of 1mm and the diode itself has a width of 4mm, you are measuring with an error of 400%: you will think your 1/1000s speed is only 1/250.