[Brightcolours]

"Only" 21mm f/2.8? Sounds pretty good by me. Besides, it's probably optimized for IQ, and outright compactness was probably not on the agenda. Compare the performance of the ZF 21mm and the Color-Skopar 20mm - they were both tested here in the Zone - and you'll see why. But I'm sure you already know it all.

The 20mm f3.5 tests badly at PZ MFT distances, but performs better at normal "infinity" distances. And you are right, corrections make a lens bigger.

I meant the "only" as in 21mm f2.8 is not spectacular, so the lens is not remarkably small. But the lens sounds good to me too.  B)