ZD 8mm question

Can anyone tell me what is the critical sharpness of ZD 8mm?

\- I presume ZD 8mm is the best at F5.6, like most other ZD pro lens, but I don't know how good is that "best".

Anyone mind posting a few ORFs @ ISO100 or 200 for me to test a bit?

\- I would also like to see what can I do about CAs and distortions. Online JPEG samples aren't good enough.

I have an opportunity to get this lens for relatively good price, but it is not sharp enough I doesn't make much sense getting it.

Thanks a lot in a advance!