ADi, thanks for the data. They confirm that I was imagining the correct configuration. The key bits for me are 5X and NA 0.15, which establish the diffraction limits.
Again, by my calculations your computed MTF curve cannot possibly be correct because it is way better than diffraction permits. This means that your test protocol is not valid, which means that using it to compare configurations will be a waste of time.
So let's go back to things that might be causing the problem.
First, you should not be over-exposing the light background.
Background should be uniform light gray. To make this happen, just position the paper far back from the razor blade, so that it is completely out of focus. At 5X NA 0.15, placing the paper an inch or two behind the razor blade should be OK.
Second, it is critical that the small image that is fed to MTF mapper is constructed by
cropping without resizing. With your optics, MTF mapper at 100% should be showing that the edge transition takes place over a span of 2-3 pixels, as shown in your other thread at
http://www.photomacrography.net/forum/u ... _prg_1.jpg :
I suggest to try again, paying special attention to these issues.
--Rik