[davidmanze]

Yes, that is why there is such a big difference between f-value and T-value. The apodiation element is the cause.

 

No automatic aperture is not a big deal with this lens, as it will mostly be used wide open or close to wide open. Just like it is no big deal with my adapted 55mm f1.2 lenses for instance. The purpose of the lens is portraits with shallow DOF and smooth bokeh.

Thanks BC!

                   Does the Nikon AF105mm DC (defocus control)  lens use the same principle and how does the adjustment ring work?  Personally I would much rather get a S/H copy of that lens as it has it all, it's one of Nikon's sharpest and best built all metal lenses and a built in lens-hood.