Posted by Spex on 09/07/06 16:31

Richard Crowley wrote:
> Acurajustin1978 wrote ...
>> I know what a CCD is... but when I see the sizes listed it will say
>> something like 1/6 or 1/7.5.
>> What does this mean? One sixth of an inch?
>> Obviously I'm guessing bigger is better.
>
> It is the *diagonal* measurement of the imaging surface,
> measured in inches (for better or for worse). It is measured
> diagonally because lenses are round and that is the *diameter*
> of the image that must be delivered by the lens.
>
> Bigger means more sensitive imaging devices (because
> there are more photons hitting each "pixel" to turn into
> an electrical signal). However, bigger also means larger
> (and significantly more expensive) lenses to deliver an
> appropriate image to the chip.
>
>
That's not strictly correct. One has to factor in the resolution of the
CCD. A large high resolution CCD can be and often is less sensitive
that a smaller low resolution CCD.

A Pedant.

[Back to original message]