Originally posted by glasbak Who says, they are the same ?
Anyway, look at these diagrams,
FA100 and
DFA 100.
They appear similar, but not the same.
And even if they were the same. looking at the FA100 diagram, you will notice that there is a lot of opportunity to make the lensbarrel smaller.
I was conjecturing that they are all the same, since the PentaxForums lens database lists the DFA WR version as optically the same as the DA, and the DA as optically the same as the FA. Perhaps they're not, if the tests are wildly different.
The MZ-S does indeed support auto-aperture, but you're locked out of any mode that allows you to adjust the aperture. Essentially you only get Program or Tv, no Av or M. I use Av mode most often (and Manual when working with strobes/macro, which I plan to use extensively), so I settled on the FA version. The DFA was another possibility, but I really wanted the AF limiter for portraits.