
This is about 4.5mm across the field. At this magnification, even f/8 is starting to get fuzzy from diffraction. We can pull out a bit more detail by cropping closer, but not much:

The setup for this was a bit cobbled together. It's the Olympus 38mm f/2.8 bellows rig that I use for stacking, but handheld and stopped down to f/8. Stopping down sacrifices some resolution compared to what the lens will do wide open (see the comparison here), but it gives more DOF in a single shot while still being sharp enough for the web.
Optically, the setup is similar to an MP-E 65 at maximum magnification. It's rather less convenient, but I already had this and I don't have an MP-E 65. Tradeoffs, tradeoffs...
--Rik
Canon 300D, Olympus 38mm f/2.8 bellows lens at f/8, crops from 5mm field width = 4.5X onto the sensor, strobe lighting.