|
Its interesting looking at the data. The larger 1 1/8 inch chip has a Well Depth of 14,000 e- vs the Well Depth 40,000 e- of the 640x480 chip, so the smaller chip can hold more charge or photons. Generally, the higher the number of photons, the better your signal to noise ratio so the images look rich and full as opposed to thin and grainy.
Bert explained in an older post that small pixels in consumer ccds are analogous to fine grain film – they require a lot of light to ensure that you have plenty of signal to keep noise (or grain) to a minimum.
The 640x480 chip can operate at 60 FPS due to the relatively small number of pixels to be read and downloaded, whereas I note the 1616 x1232 chip spec is 12 FPS.
Somewhere there is a formula which you can use to calculate the optimum pixel size for your focal length. If you have “too many” pixels then you are over sampling and wasting data. If you have “too few” pixels your stars will look blocky. I’ll post it when I find it.
Cheers
Dennis
|