I have an old camera which I know has a sluggish shutter speed, but just how slow? I tried a couple of techniques to estimate it, including video, but wanted a solution that had more accuracy. Video only has 1/30 or 1/60 frames per second, depending upon your device, and it's just too clumsy to use that method. Searching online, I found various solutions based upon using a photo sensor and the computer's sound card.
I decided on one of the more simple solutions, requiring just the parts seen in the photo, obtained at a local Radio Shack, except for the foam board, which I had purchased from an arts and crafts store. The foam board just gives it a cheap and stable base; a better solution would be to mount everything in a small box, but it may or may not make it easier to use.
Parts used to make the shutter tester project.
Basically, the idea is that you shine a light through the camera and when you engage the shutter, the photo receptor will respond. This response can be recorded on the computer as if it were an audio signal. Since the computer can record at high rates of speed, the shutter speed can be fairly easily determined. Note that the response from the photo receptor is a bit odd with this simple circuit, bouncing a bit as the light goes off, making it a bit more difficult to get a reading.
I'll leave it to the linked articles for the details of how to wire the project and how to interpret the recordings.
Through this process, I was able to test a camera I had just purchased, verifying that the shutter speeds were pretty accurate.
How to make an accurate shutter speed tester - Photo.net Large Format Forum
Test Equipment - Combination Shutter Speed-Curtain Speed Tester
Do not attempt this project unless you are familiar with working with electronic circuits. This is not a how-to guide, just information on what options are available.