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Old 23-09-2019, 10:36 PM
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billdan (Bill)
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This is taken from the Starizona website - Note there is no distinction made between Mono or OSC.


Quantum Efficiency
As photons of light hit a CCD chip they are converted into electrons which are stored and then read out at the end of the exposure. But not every photon that hits the chip is converted into an electron. How many photons are converted depends on the camera's quantum efficiency, or QE. QE is expressed as a percentage of the number of photons converted.
If all the photons produced electrons, the QE would be 100%. Most amateur CCD cameras have QEs in the range of 25-50%. More advanced "back-illuminated" CCDs have QEs around 85%. Supercooled professional CCDs used at observatories have QEs closer to 98%. Compare this to film, which has a typical QE of around 2%.
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