How to measure frame rate of a CCD camera

[Brian@Channel]

I have a CCD camera with a built in frame grabber. The camera transfers the image data to a PC via a custom PCI card. The software does not provide a tool to measure frame rate. Anyone have a suggestion on how we may confirm frame rate. It is rated at 30 fps, but we are skeptical. Maybe take images of a moving target or clock with 100 ms resolution?

[BruceAmmons]

Brian,

One possibility would be timing how long it takes to acquire a large number of images. For example, start a timer, acquire 300 images, and stop the timer. If it is 30 fps, your timer will indicate 10 seconds. This requires the ability to acquire a fixed sequence of images, and a reasonable knowledge of when the acquisition starts and ends.

Another possibility is recording a slowly rotating (or oscillating) object with a known frequency around 1-5 Hz or so. You could count how many images it takes for each revolution. Counting 10 or 50 revolutions would be even more accurate. It would be fairly easy to measure the frequency of your rotating object with a stopwatch.

I wouldn't try digital clocks or timers. Even if they have 100 ms accuracy, th
ey don't usually update that fast. The results would probably be very confusing. However, it would work if you did the long sequence and figured out the total time and divided by the number of frames minus one.

Bruce

[Jonathan P]

i wanted to attack exactly the same problem a couple of weeks ago and was about to make up a fast LED timer, which i could image. At the last second i realised that my camera had an exposure out connector which provided a TTL pulse whenever the CCD was being exposed. Does your have something similar. Alternatively i have imaged a small LCD stopwatch before which gave me 50ms resolution. I could not properly image each frame but, say 1 in every 10 frames showed a readable number on the stopwatch and therefore i could get the frame rate that way.