"Joseph Meehan" wrote:
rafe b wrote:
On 7 Jan 2006 01:20:47 -0800, "John" wrote:

What is the main difference between a full size sensor (EOS 5d) and
a smaller sensor size (Nikon D200). Is a smaller sensor worse in
getting light/resolution compared to a full size sensor? Why is a full
size sensor more preferable?

In the same way that bigger film formats
are better than small ones.

Not exactly. But in a way yes.

A larger sensor is just that a larger sensor. Assuming the same number
of pixels and equivalent lens focal length and aperture you may expect at
least one difference and that would be a reduce DOF of the larger sensor
system.

With the larger sensor, you just stop down one more stop and use a higher
ISO. The smaller system gets bitten by diffraction earlier than the larger
one, so can't be stopped down as far, and the larger pixels in the larger
sensor mean that you get the same image quality (noise) at the higher ISO
that the smaller sensor gets at the lower ISO. The larger format gives you
the option of using a lower ISO (with better noise) at a slower shutter
speed, of course.

That's assuming the pixel count is the same. With a higher pixel count,
things are a tad more complicated. Then it's more like film, where you have
to work harder with the larger format to get the full advantage of that
larger format.

However other dynamics come into play and usually full size sensors
(same number of pixels) will produce a better result do to physical
constraints. However a larger sensor will often have more pixels so it
will be recording more information.

The best way to answer this question is to actually work with both
combinations and see what works best for you. It is the same sort of
questions about using 4x5 or 2¼ and using a faster film speed in the 4x5
or not etc. Much of the difference is very difficult to describe or
quantify.

It looks to me that larger formats are even more of an improvement in
digital than they are in film. In film, larger formats have worse film
flatness problems, both at capture and during projection printing or
scanning, and lenses are often funkier. But digital resolutions are so low
that providing adequate contrast at the max resolution of the sensor usually
isn't terribly difficult.

David J. Littleboy
Tokyo, Japan