Originally Posted by Peter Ericsson
Taking an image with the same lens using both the 40D and the 50D. Cropping it and resizing it to let's say 800 x 600. Which camera produces least noise?
Peter, this isn't the question you should be asking.
Suppose you take a shot of a bird that takes up one-fifth the height of your image. On a 40D you could crop that from 2592 pixels high to 600 pixels high and you'd have the bird (518 pixels high) contained in your cropped image.
But on the 50D the bird would take up 3168/5 = 634 pixels. If you cropped that image to 600 pixels high then you'd be cropping part of the bird.
The question you really want answering is -
Taking an image with the same lens using both the 40D and the 50D. Cropping it and resizing it to let's say one-fifth the linear dimensions. Which camera produces least noise?
And I'd bet money that the answer would be - they're about the same.