Didn't do this on purpose, but after uploaded the pictures noticed the two were taken at aproximate effective apertures and 4x to 5x magnification with Canon MP-E 65mm
Fly portrait by
Gustavo Mazzarollo, on Flickr
Focus stack of 2 pictures with Canon MP-E @ 5x and f/5.6, manual stack in GIMP.
Effective aperture of f/33.6 Theoretical DOF of
0.095mm each photo
fly2 by
Gustavo Mazzarollo, on Flickr
MP-E @ 4x and focus stacked from two frames at f/7.1, zerene stacker.
Effective aperture of f/35.5 Theoretical DOF of about
0.15mm each photo.
I think this time the DOF expansion of the lower magnification resulted in even more detail considering these photos are stacks, the magnification increased the size, but not the detail of the eyes.