Quote Originally Posted by Jon Ruyle
<span>John, if you'll excuse my saying so- and I mean this in the nicest way possible- you're being silly. You are comparing taking pictures with different sized subjects (by subject size I mean the linear size of the focal plane).

Jon, forgive me, but I have to say that I don't find it 'silly' at all. If you're taking a picture of an insect, you frame appropriately, and for one bug there's one 'size' to work with. Not all subjects are such that there is one appropriate size for the image. Here are a few examples:





In all four of those cases, a looser or a tighter framing would work. No, it wouldn't be "the same picture" but with a repetitive pattern that just means more or fewer repetitions are included in the framing, and with an amorphous subject, same idea. A reasonable approach with a standard macro lens is to simply shoot at 1:1 (or whatever mag is desired) - at least, reasonable to me, and I often shoot in just that manner - manually set focus at the MFD, then move camera+lens closer to the subject until a pleasing focal plane is acheived, and shoot. In that case, sensor size does matter, because at a fixed distance, the larger sensor delivers a deeper DoF and less diffraction - to me, those are often advantages.