06-13-2016, 12:26 PM
(This post was last modified: 06-13-2016, 12:43 PM by Brightcolours.)
This lens keeps its aperture closed to the aperture setting you use, which is nice for judging DOF in live view but apparently it also means slower and slower AF the smaller the aperture is. Sony says it is done to cut the time it takes for closing the aperture down when taking a photo, but the resulting slower AF speed is a much bigger issue... Puzzling decisions (which include the noisy and slow DC motor choice).
Also, this lens has a similar/same double gauss optical design as the above mentioned cheap Canon EF 50mm f1.8/EF 50mm f1.8 II and its follow up, the EF 50mm f1.8 STM. That means all elements move during focussing, so maybe that explains the choice for DC motor. The EF 50mm STM costs less than half than this Sony, though.
Also, this lens has a similar/same double gauss optical design as the above mentioned cheap Canon EF 50mm f1.8/EF 50mm f1.8 II and its follow up, the EF 50mm f1.8 STM. That means all elements move during focussing, so maybe that explains the choice for DC motor. The EF 50mm STM costs less than half than this Sony, though.