John Francis wrote:
Not all FA lenses are zoom lenses, but they still get the FA name.
I think that the FA lenses were the first ones to include MTF data
in the ROM chip. That's only important if you use that feature by
selecting the appropriate program line. It's also possible that
there is some other lens-to-body communication (focus distance?)
that is used in multi-segment metering and/or flash compensation;
Pentax have remained silent on the detailed differences.
Some years ago I've been confirmed by a Pentax designer that FA lenses have
more advanced electronics, telling the camera the focusing distance (among
other things). That's the reason for having FA-series prime lenses.
Dario
