You said that better than I could have Steve. Collin, we are talking about the same lever aren't we? The aperture actuator lever, not the aperture simulator lever for the meter? This is always calibrated, but not used at all the D.
Don (Off to work now) > -----Original Message----- > From: Steve Jolly [mailto:[EMAIL PROTECTED] > Sent: Thursday, May 26, 2005 9:41 AM > To: [email protected] > Subject: Re: "A" need > > > Collin Brendemuehl wrote: > > It doesn't make mechanical sense > > > > If two 50mm (K & FA, for the sake of argument) lenses > > have the indicator set to f "8" and f "2" is the same > > diameter, for the body to close the mechanism down to > > f "8" would not the distance be identical? > > On the original K-mount, moving the stop-down coupler closed the > aperture until it reached a mechanical stop, set by turning the aperture > ring. You could continue to move the coupler beyond this point but it > had no further effect on the aperture. Hence the relationship between > absolute coupler position and lens aperture could be undefined, because > all the body had to do was move the coupler through its full range to > ensure that the lens was set to the correct aperture. > > With later K-mount versions (for A, F, FA and D-FA lenses), this mode of > aperture setting was maintained, but in addition, the aperture could be > controlled from the body by moving the mechanical stop out of the way > (by setting the lens to its smallest aperture) and only moving the > stop-down coupler part-way. In this scenario the relationship between > coupler position and lens aperture must be strictly defined, since > that's how the aperture is actually set. > > FAJ and DA lenses lack the aperture ring and its mechanical stop > entirely and their aperture can only be controlled from the body. > > Make sense? > > S >
