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?

Thanks,
--j

At the pixel level, given the same number of pixels between the
two cameras, the larger camera has larger pixels which collect
more light giving a higher signal-to-noise ratio and larger
dynamic range, See:

Digital Cameras: Does Pixel Size Matter?
Factors in Choosing a Digital Camera
http://www.clarkvision.com/imagedeta...el.size.matter

Larger pixels also are more forgiving regarding lens
aberrations, and diffraction. Its a quality win win situation
at the cost of bulk, weight, and cost of the larger camera.

The D200 has 6.1 micron pixel pitch and the 5D has 8.2. Both are
working in the sweet spot for great imaging (6 to 9 micron range)
which gives great signal-to-noise and large enough pixels that
lens performance is great. The 5D, having more pixels and
that are slightly larger has theoretically better numbers (but I
don't know for sure because the full well capacity and read noise
have yet to be published). In any case both should be great
cameras, given good lenses. Some more info with digital camera
specs:

The Signal-to-Noise of Digital Camera images
and Comparison to Film
http://www.clarkvision.com/imagedeta...ignal.to.noise

Roger
photos at: http://www.clarkvision.com