Originally posted by Wheatfield Well, not quite.
Technically, the lens cannot transmit data, since it doesn't have the necessary electronics.
Pretty sure I mentioned that. The older lenses transmitted data via the aperture cam follower, which is how the meters in the LX, M and K series cameras knew what aperture you were shooting at, even wide open.
Wait, though, I think I got it backwards with the A series lenses. They don't transmit any data, per se, to camera. With the lens set to the "A" on the aperture ring, it's stopped down all the way. When the shutter's fired, the camera lets the lens stop down, and (by measuring the resistance of a variable resistor connect to the aperture?) and when it detects the correct aperture it prevents the lens stopping down any further.
I agree, Pentax should've kept the KAF2 and not messed with a good thing. Trouble is, with the digitals being so densely packed and small, I'm wondering if there's any room left for the aperture cam follower.
Man, if we get that Pro Pentax soon (yes, I know the current iterations are perfectly fine for "pro" use, and that it's not the gear that maketh the photog, I'm speaking from a marketing perspective if anything) I hope it's full KAF2.