Let me explain my idea a little more: If a camera (not necessarily the *ist) has no aperture simulator, it can still properly measure the amount of light provided that it does not meter at open aperture. As a camera like the *ist offers e l e c t r o n i c depth-of-field preview, such camera might automatically close the aperture with every lens that is not in "A" position. In this case the camera would not need to know the selected f-number (like it does not know with the K28/f3.5 shift lens).One more thought: Maybe we are all right, and the *ist works with K- and M-lenses, but only with stop-down metering?
Arnold
Boz wrote:
I don't think so. Stop-down metering indicates that the lens lacks the mechanical aperture coupling. For example, if the aperture is deep into a tele lens, it is normally too complex to create a mechanical coupling between the aperture and the lens mount. This is why the Pentax shift lens has manual aperture and Canon's has fully automatic --- because they lead the aperture signals with flexible wires to the aperture-control mechanism which sits in front of the tilt-shift mechanism.
The problem with the newset Pentax bodies is that the body is not able to read the aperture selected by the lens. It assumes widest aperture, and if you stop down 2 EV, the camera overexposes by 2 EV.
I cannot imageine how much weight or money Pentax is saving by this, but it must be significant, since they have at least tree bodies with that mount (MZ/ZX 30, 50, 60).
