Some dumb questions I have been wondering about

Started Mar 28, 2013 | Discussions thread
jonikon Veteran Member • Posts: 6,078
Re: Some dumb questions I have been wondering about

Wellington100 wrote:

1) Why are camera sensors not square? Surely a square sensor is the most efficient way to get the best out of a lens?

It's the aesthetics. How many paintings have you seen that are square?

2) Does using a Polarising filter reduce the Dynamic Range of an image taken in sunlight with a digital camera?

Not directly, but indirectly they can. The reason is that a typical polarizing filter reduces the light hitting the sensor by about two stops. If the ISO is raised to compensate for the reduction in light, then the dynamic range will be reduced. (With present day sensors, as the ISO goes up, dynamic range goes down.) An alternative would be to increase the exposure, typically with a longer shutter time which will sometimes require use of  a tripod.

3) Why do most cameras have IQ reducing AA filters when the few cameras that don't have them jump in IQ and moire is nowhere to be seen in 99.99% of the images?

An AA filter is not necessary once the spacing of the photosites gets very small and therefore a 6 MP APS-C  sensor will be prone to moire, while a 24MP sensor will not. Because of the density of their photosites, the small sensor P&S cameras shed their AA filters some time ago, and now DSLRs are doing the same.

4) What is the optimum resolution for small camera sensors? High resolution sensors seem to add significant file size for little discernible improvement in resolution, so what is the cut off for a functional and well rounded small sensor?

Years ago I read a well reasoned article on web that made a case for a maximum of 6 MP for small sensor camera. Based on my experience with P&S cameras, I believe this may be a bit conservative, but certainly not very far off. The P&S camera that gives me the best image quality and most accurate colors is the 6MP  Fujifilm F31FD. To this day there is no better tiny sensor for high ISOs.

"Pay no attention to that man behind the curtain! The Great Oz has spoken!"

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- Jon

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