[H. J. Simpson]

But the (modern) primes are of course nonexistent, apart from the 55/1.4 which is a "secretly FF" lens.

 

In prime land the following are FF, 31/1.8, 35/2.4, 35/2, 43/1.9, 50/1.8, 50/1.4, 50/2.8 (macro), 55/1.4

Strangely, the dpreview article mentions 55/1.4 compatibility as "stopped-down" only, and not "fully functional". I wonder what that means exactly. I was thinking about buying that lens, but only if it'll work on FF body with no issues. If it's not usable wide-open on K1, then it's not worth it (it's not exactly cheap for what it is, most 50/1.4 from other companies are cheaper).