3 ms·
Err, modern global shutters like those made by CMOSIS/ams are _much_ faster than that. Their fast one is an APS-C sensor with 4k*3k Px, a shutter closing time
by namibj 8y ago
Err, modern global shutters like those made by CMOSIS/ams are _much_ faster than that.
Their fast one is an APS-C sensor with 4k*3k Px, a shutter closing time of 1s/~120000 and a minimum shutter open time of ~1s/50000. The shutter closing time might be even faster, just reconstruction from frame overhead time values I remember, and adjusting for the share the row skew had. Check the datasheet if you like to.
If you know a mechanical shutter that can do such, I'd like to know.
This, by chance, allows laser-flash illumination of objects that are behind a close wall of fog, as you can keep the shutter closed while the light travels to the further away object of interest. You will have the blur, but no longer the massive constrast loss due to light pollution. If it's not as bad as fog, and just e.g. normal rainfall or such, you lack the reflection artifacts that would be common, and only retain the refraction artifacts from the light passing through it by necessity.
These sensors do lack a little dynamic range, but you can compensate with some slight trickery, see the datasheet, to get ~15 stops out of this particular device.
Rolling shutter has applications, but videos for users of low knowledge and high ambitions is not one of them.
- nickparker 8y agoCould you expand on or link the bit about time of flight trickery in fog or rain? c * 1 s / 50,000 is still kilometers, so I’m not sure I understand how this shutter can do what sounds like using time of flight to selectively illuminate stuff at a specific depth
- namibj 8y agoNo, the part that can solve this is the fast time from insensitive to sensitive, which is shorter than the time form sensitive to no longer sensitive. You will need a pulse with a short enough duration, e.g. a Q-switched Nd:YAG with frequency doubling giving you up to about a dozen Joules at up to a few hundred Hz with pulse durations of under 50 ns, and, while limited in some ways by breakdown peak power in components, a lower limit of about .5 ns. Most of the shutter time is used to copy the data to the shadow pixel, but just releasing the dark pull won't take long.
- Sharlin 8y agoYes, global shutters are a thing in expensive professional video cameras. But almost every camera in the world is a phone camera prone to rolling shutter effects both in stills and video shooting. Out of the rest, almost all have mechanical shutters for stills shooting and electronic rolling shutter for video. It’s going to be a while before global shutters become a thing in consumer cameras.
- namibj 8y agoWhich is sad, tbh. Because global shutter, white slightly more expensive in terms of area for a given SNR, can do things to both compensate and just generally do "weird" things.