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Sony FE 100mm f/2.8 STF GM OSS Overview
By B&H Photo's
Bjorn Petersen
The Bokeh Master
Delivering both smooth bokeh and fine sharpness, the FE 100mm f/2.8 STF GM OSS from Sony is a short-telephoto prime featuring a unique and sophisticated optical design. Separating itself from other portrait-length lenses, this 100mm f/2.8 features Smooth Trans Focus (STF) technology, which uses an apodization filter to realize notably smooth bokeh with rounded out-of-focus highlights in both the foreground and background.

Smooth Trans Focus
Optical design incorporates an apodization (APD) element that helps to improve the quality of bokeh. This element, which resembles a radially graduated ND filter that tapers from clear in the center to denser around the edges, produces more circular out-of-focus highlights for more pleasing selective focus and shallow depth of field effects.
An aperture range of f/2.8 to f/20 is available, however the implementation of the apodization filter renders this range as T5.6 to T22.
A rounded 11-blade diaphragm further contributes to a pleasing bokeh quality when employing shallow depth of field techniques.

G Master Optics
G Master lenses prioritize sharpness and bokeh quality by featuring advanced optical designs and specialized elements.
One extra-low dispersion (ED) element reduces color fringing and chromatic aberrations while one aspherical element controls spherical aberrations for improved clarity and sharpness.
Optical layout has also been designed to reduce peripheral highlight distortion due to vignetting in order to achieve rounder out-of-focus highlights in both the foreground and background.
A Nano AR Coating has been applied to reduce surface reflections, flare, and ghosting for increased contrast and color rendering in strong lighting conditions.
Autofocus and Macro Switching

Direct Drive Super Sonic wave Motor AF system provides quick, quiet, and precise autofocus performance and also contributes to more natural, intuitive manual focus control.
Internal focusing design offers more responsive focusing performance and maintains a consistent overall lens length during operation.

Macro switching ring allows you to choose between two focusing ranges: 2.8' to infinity or a closer range of 1.9-3.3'.
Maximum magnification of 0.25x at minimum focus allows for near-macro capabilities for true close-up detail shooting.
Customizable focus hold button on lens barrel can be used to hold the focusing position, or can be set in-camera to control a variety of additional lens functions.
Handling and Physical Design

Optical SteadyShot image stabilization helps to minimize the appearance of camera shake for sharper imagery when shooting handheld with slower shutter speeds. This stabilization system can also be combined with select camera's sensor-shift type image stabilization for more effective control of camera blur.
Manual aperture ring can be de-clicked for smooth, silent aperture switching to benefit video applications.
A dust- and moisture-sealed design better permits working in inclement conditions and rubberized control rings benefit handling in colder temperatures.