Originally posted by Just1MoreDave On some lenses the contact pin moves in and out when the aperture ring is moved on or off the A position.
You are correct. That is exactly what happens.
Originally posted by Just1MoreDave In all the modes except M, the camera will keep the aperture fully open when you shoot, ignoring any aperture ring setting. In M mode, if you enable using aperture ring, the camera will use the aperture ring setting when you take a shot. It can also meter, usually with the green button. To get a meter reading, the camera stops down the lens temporarily, measures light, then opens it again. That will calculate a shutter speed for you.
Right, this is what I have tried on my K3:
a) When on M mode, have aperture ring set and lense on "A" mode, then I can use the back wheel to set the f value.
b) When on M mode, have aperture ring set and lense on any value except "A", I get F-- on the screen but when I press the green button, the finder goes black a tiny bit and the shutter speed gets set to a specfic value (but the screen still shows F--). If i change the f value on the lense by turning the ring and press the green button again, the shutter speed changes. I assume that this means that there is metering going on. I assume this means that the mirror is raise so that the light corresponding to the aperture can hit the sensor to obtain metering (this is what is meant by "stops down the lens temporarily"?)?
c) The behaviour I describe in b above does not occur on any other camera setting other than "M" mode, even when I put the lense on "A". THe green button seems to have no effect at all unless the camera setting is on "M".
Originally posted by Just1MoreDave If you get the A position working, there are few reasons to move it off A.
Now this is what I don't understand from your post. What I have asked myself is what difference is there with having camera on "M", lense on "A" and then using the wheel to select aperture and leaving camera on "M", selecting a setting for apearture on the lense ring and then pressing the green button. From what I see, the only difference is that you do not need to set the shutter speed with the front wheel when not using the "A" on the lense. Anything else I'm missing?