John wrote:
> I believe the 35mm sensor remains in the new Leaf ProDigital6, which
> leads me back to my after-thought question: Is there any distinct
> advantage to a larger format size (large vs. medium vs. 35mm) for
> digital image production. Specifically, will one get more image
> information from a medium format camera with a digital back than with a
> (smaller, lighter, more transportable and less intrusive) 35mm digital
> camera of equal resolution?
Assuming that two sensors have the same number of pixels, a larger sensor
will have larger pixels. The primary advantage of larger pixels is the
greater ability to collect photons. This translates into lower noise and
greater resistance to overloading for any given bias (sensitivity) -- in
other words, for any given EI, the larger sensor has lower noise and
greater dynamic range.
There may be secondary effects, as well. For example, sensor chips have
color-separation filters, [spatial] lowpass filters, and sometimes lens
arrays in front of the pixel wells that may be easier to apply or align
accurately with larger pixels. Also, the portion of the frame covered with
conductors and other non-pixel well structures will be a smaller portion of
the whole.
There's at least one secondary effect that depends only on image size. For
any given lens coverage angle, the smaller format will have greater depth
of field at a given aperture.
So, yes, there is a difference. Whether you can see it or not in most
real-world situations is another matter.
On the other hand, a larger size chip also allows more of the same size
pixels. Since the 11Mp Canon 1Ds seems to have perfectly adequate pixels,
I'm waiting for a 44Mp x 16 bits/color 6x7 cm sensor. Or, better yet, a
4x5" sensor with 176Mp at 16 bits/color. With a Digic 3 processor to
match! (Note that the chips don't have to be as big as the deployed
sensors -- some cameras made for telescope imaging use arrays of chips very
successfully.)
Best regards,
etienne
Received on Wed Apr 7 20:20:54 2004
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