OK, the plot thickens. I've been busy with PZ-1, two 50mm lenses, a tripod,
notebook and a standing lamp across the room.
I set both the 50/1.7 F lens and the 50/2.0 M lens at 2.8 for this, and made
comparisons with the spot area on three areas on and around the lamp. Results
are similar to those last night with my 50/1.7 F lens and 50/1.4 M lens and no
tripod (in a different room, with a different lamp).
For each position I made readings with each lens with the "spot" button
activated and unactivated. With the M lens, I only activated the spot button
with the Pentax Function set to SP. With the F lens, I tried it both with the
PF set to CE and to SP.
In each case, both last night and tonight, the camera showed me the same
shutter speed regardless of the "spot" button when using the M lens. Also in
each case, this shutter speed was the same as the F lens in SPOT mode. Not
centre-weighted, not multipattern, but SPOT mode.
