This thread is a followup thread on "ArduCam OV5647 Camera Board w/ M12 Mount"
where I made global shutter videos with Arducam ov5647 camera. That camera is like v1 camera (both are based on ov5647), but with exposed FREX and STROBE pins, which I used for global shutter videos.
In thread "Re: pigpio C sub µs single pulse generation" I was able to generate 9× multi exposure frame of propeller rotating with 22000rpm (>35.5m/s at blade tips), with strobe pulse duration of 9µs, 116µs apart:
In old posting "Re: Is there any photo/video of flying rifle bullet done with v2 camera?"
viewtopic.php?f=43&t=234416&p=1443728&h ... e#p1441533
I described my at that point new airsoft pistol and measurements, which led to a potential calculated speed of 92.8m/s.
Today I did capture for the first time flying 6mm diamter yellow bullet in flight after being shot with that pistol. If I would have used the waveform fixed number of flash pulses technique from above posting, I would had to have a synchronization between shoot and video capturing. Instead I used PWM to generate the flashes this time. I moved all equipment from top of plexiglas on my Motor Test Station down to the flow. The camera was directed so that there was no obstacle before big black shelf 4m distant (in order to minimize unwanted light sources). And I switched to 20° lens. Then I calculated (on the wrong assumption of 92.8m/s) what frequency I would need. I ended up with 3kHz, and 2.5% duty cycle, which results in 8.33µs strobe pulse duration. In order to not affect AWB I did emit the PWM signal only for 2 seconds, and after having started the command and the 5000lm led with reflector emitted bright light, I triggered the shot (video was captured with raspivid and "-fps 1"):
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$ pigs hp 13 3000 25000; sleep 2; pigs hp 13 0 0
Below is not perfect, just the first capture of flying bullet, not sharp because lens was not adjusted well, but it is a prove that capturing (rifle) bullets in flight is possible with v1 camera!
Just later I realized that the frame allowed me to roughly estimate the bullet speed while flying through camera view! The bullet diameter is 6mm, and I used gimp to measure diameter of bullet as 357 pixel. The distance from left side of 2nd to left side of 3rd bullet in frame was 563 pixels. It tuned out that the bullet (at least in view of camera) speed was much lower than hoped for:
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(563/357*0.006)*3000 = 28.38m/s
There is no problem to get enough speed, a friend has three air rifles of different speeds, that will be done later, after having provided the needed tools for taking global shutter videos with v1 camera.
Here you can see the 2MP global shutter frame copied into 5MP photo of the setup on floor. I will have to reduced the setup so that it will become mobile and I can take it to friend with air rifles, or later to gun club for higher speed bullet capturing: