-A and up lenses have a series of contacts at the lensmount interface, that correspond to areas of metal or plastic on the lens. This codes the minimum and maximum aperture of the lens. There is also a real contact on the lens to indicate whether the aperture ring is set to the "A" position.
-Mat Jostein wrote: > > From: "Alin Flaider" <[EMAIL PROTECTED]> > > > > Think about A and up lenses - they all have electric contacts > whose > > pattern tell the camera the absolute value of lens widest > aperture. > > Now setting the actual aperture is a matter of setting the lever > > position according to the difference between the max aperture and > > the target one. > > That makes sense. But all the A lenses have only one contact, don't > they? > Sounds like electric resistance values to me. That alone can't tell > the camera house the absolute value of the largest aperture. My guess > is that the camera actually figures out the max aperture from reading > how high the lever is pushed by the coupler handler when the lens is > mounted. > > Jostein
