Originally posted by mattdm They apparently skipped that last one too — there's a review of the Canon version just up
on photozone.de, and it notes that turning the aperture dial actually darkens the viewfinder.
yes, that's because canon, sony and olympus mounts require digital connection between the lens and the camera - lens aperture is activated without any mechanical links, it's triggered by digital signal. so, without electronics of any kind, lenses in EF, FT and MA mounts cannot have aperture automation.
on the other hand, nikon F and pentax K mounts have mechanically linked aperture lever - no problems with lens automation whatsoever.
as far as i know (somebody on this forum have Polar-branded 85/1.4 lens), samyang lenses are KA lenses - like pentax-A, Voigtländer K-mount, and Carl Zeiss ZK lenses.