As focal lengths get longer, lenses built with conventional optical glass have difficulties with chromatic aberration, and as a result images suffer from lower contrast, lower color quality, and lower resolution. To counter such problems, ED glass was dev, ED (Extra-low Dispersion) glass / Super ED glass. SSM is a piezoelectric motor that contributes to smooth and silent AF operation. The motor produces high torque at slow rotation, and provides immediate start and stop responses. It is also extremely quiet, which helps keep autofocusing silent. Lenses tha, SSM (Super Sonic wave Motor). In general, if an aperture uses 7 or 9 aperture blades, then the shape of the aperture becomes a 7-sided or 9-sided polygon as the aperture is made smaller. However, this has a certain undesirable effect in that the defocusing of point light sources appea, Circular aperture. Focus hold button, Once youve adjusted focus to where you want it, pressing this button on the lens barrel will keep the lens locked to that focusing distance. The preview function can also be assigned to this button through the cameras custom settings. Original Sony Nano AR Coating technology produces a lens coating that features a precisely defined regular nano-structure that allows accurate light transmission while effectively suppressing reflections that can cause flare and ghosting. The reflection s,Nano AR Coating. This function allows you to set a limit on the focusing range which can save you time during auto focus operation - as the lens will not hunt through the entire focusing range. In macro lenses, this limit can be on either the near or far range. Certain, Focus range limiter. Advanced Distance Integration provides precise distance information through the lens distance encoder to the built-in flash, or certain Sony external flashes (HVL-F60M, HVL-F43AM, HVL-F32M, HVL-F20M). ADI provides automatic metering that is virtually unaf, ADI flash metering.