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Posted by Rick Merrill on 09/07/06 18:12
Richard Crowley wrote:
> "Rick Merrill" <rick0.merrill@NOSPAM.gmail.com> wrote in message
> news:rL-dnRtQBKQ53p3YnZ2dnUVZ_oKdnZ2d@comcast.com...
>
>>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.
>>
>>Mmmm, I think you are on to something: the round lense image must
>>fit INSIDE the square CCD; therefore it would make more sense for
>>the CCD to be measured along it's edge: the diameter of the round image
>>that would just fit.
>>
>>So I think CCD is measured square, not diagonal like the big screens.
>
>
> I think you have it backwards. The diagonal of the chip
> must fit inside the circle image produced by the lens.
You're saying that it's more important to use all the pixels of
the chip than to use all the circle of the lense. Sounds good to me.
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