Interesting thread. I will have to add some of my own images. Till then, since I have to say something regardless of rather I know what I am talking about or not, there are 2 points I want to make. 1. If I take a simple color image, say a plain leaf against a solid blue sky, I get a much smaller file size than if I take a many colored busy shot. Very much smaller. If the file size is smaller, how can there be as much information in one file as there is in the other? I guess to really test this, I would need to go to tif instead of jpg, I may try that and see what happens. But, if I do and find that the b/w file is smaller than the same color file, can we assume that there is less information. So, if I take a white ball on a black background in color and the same shot as b/w and one file is smaller than the other, then the actual number of light pixels captured is less and thus the definition would, I suppose, be less? 2. Never underestimate the software element. There may actually be very different approaches in how one camera handles greyscale .vs. another and that difference may yeild significant results. Of course the final result and judgment is based on the output device. As you point out a monitor is using rgb to produce shades of black and white and differnet monitors will do that with different results. Same is true with printers or any other output device. I actually read somewhere that taking a color photo as a negative and then converting it on the computer later produced better results than taking it the normal way. I still haven't figured that one out either.