[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Leader Strike Photo



Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Terry,

I think the thing that modern CCD detectors bring is larger chip area, lower noise, and perhaps higher efficiency. Given a fixed size pixel bin, you want to get as much photon to charge conversion in the bin as possible (without filling up the bin of course) within the exposure time. This requires a larger lens aperature without increasing the focal distance. Otherwords, you need a lower fstop lens. If you increase the aperature and leave the fstop unchanged the focal length will increase proportionally which in turn will increase the image scale (or lower it, I never can remember its proper definition). In any case, the image will be larger on the focal plane so the image brightness (per unit area) at the focal plane will not increase unless the fstop is lowered.

Gerry R.



Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

At 10,000 RPM my camera very easily does 300,000 m/s. Leaders travel at about 20,000 m/s which is well within the range. But the leaders like to normally propagate at angles. So is the angle just were it happened to go, or due to slow propagation across the screen... Very hard to tell... Streamers are pretty fast at 100,000 to 10,000,000 m/s but they also tend to be very dim and they are just barely detectable at "slow" speeds. So we have most of the speed and your idea about the image intensifier is very interesting! I am wondering if modern CCDs are significantly better than those of a few years back for camera light gathering... I am not sure it is just a software or RAW file thing.