This is smallest object i've ever captured (except for tiny snowflakes from this ice dust collection). But for pollen this is very big grains (i've tried several other flower species, but all of them have so tiny grains that my macro setup simply cannot get acceptable picture: magnification is too low). Even on these "big" grains you can easily see my optics limitations, though i've tried my best to squezze maximum details from available source shots.
For two grains in focus i used averaged stacks of 64 identical RAWs (128 shots total). Two grains captured separately and combined in one picture (two unfocused grains taken from first series and averaged along with focused one). Thanks to tiny size of grains, they fit completely in DOF, even with their spherical shape: no focus stacking needed.
Gear: my usual "snowflake" macro setup (i described it in article about snowflake macro photography). Daylight from left side, diffused through white plastic bag. Background: black glass plate.
Here is comparison table of cropped grain in 1:1 scale: single JPEG and RAW, unprocessed and post-processed averaged stack:
Here you'll find another photo: stamen of Field Scabious with pink pollen grains: