RobertOToole wrote:Then I processed both files with the same settings and as a last step I downsized the infinity image to the same size as the short focus image using the normal default PS CS bicubic sharper (reduction) command as I would normally to reduce an image in size.
When I compared these at 100% view in PS, I do see more detail in the short focus image when compared with the infinity focus image.
There is, of course, a complementary test: upsample the lower mag image and compare that to the original higher mag image. My expectation is that when you do that, you'll again see that the resampled image does not compare well against the non-resampled one.
So my personal preference would be to go with a short focus past infinity image for the maximum amount of details and sharpness.
I think the preference depends on whether you're making an image in general, or an image of something in particular. If you don't mind widening the FOV, then I agree that you can get a sharper image, with more details in frame, by using a short tube lens or a short focus setup in order to pack as much detail as possible onto the sensor. But if you're interested in some particular FOV, then my own recommendation is to use whatever tube lens and/or focus tweak is needed to fill the sensor with that FOV. The resulting image will not look as sharp at actual pixels, but it will probably reveal more detail on subject.
As an example, if I'm OK with shooting 4 mm FOV, then the sharpest 5X in my arsenal is Mitutoyo M Plan Apo 10X NA 0.28 on 100 mm tube lens. You know, 5X NA 0.28 is hard to beat! But if my subject is really only 2 mm long, I'm better off to use that 10X on a normal length tube lens, giving around 10X magnification. That will certainly show more detail on subject than the 5X configuration does, even though the 10X image does not look as sharp at 100% pixels.