03-01-2011, 01:11 AM
[quote name='PuxaVida' timestamp='1298898899' post='6398']
So other than a solution without changing the structure would be quite interesting to read...
[/quote]
Thanks for the link... right after I put my question in to words, it occurred to me that any AF varifocal zoom lens can be made a parfocal lens if the lens (or the body) can read the focal length in real-time and then automatically adjust the focus to the last manually set focal distance. In the case of lenses with a built-in AF motor, the lens itself can do this without needing the body to do anything but just providing power.
In the past I'm sure this was done using additional elements. But still what I said could be mechanically (i.e. not electronically) implemented if the focus variation when zooming is linear or something... maybe.
GTW
So other than a solution without changing the structure would be quite interesting to read...
[/quote]
Thanks for the link... right after I put my question in to words, it occurred to me that any AF varifocal zoom lens can be made a parfocal lens if the lens (or the body) can read the focal length in real-time and then automatically adjust the focus to the last manually set focal distance. In the case of lenses with a built-in AF motor, the lens itself can do this without needing the body to do anything but just providing power.
In the past I'm sure this was done using additional elements. But still what I said could be mechanically (i.e. not electronically) implemented if the focus variation when zooming is linear or something... maybe.
GTW