SAL-135F28 - 135mm f/2.8-4.5 Telephoto Lens
A unique telephoto lens for smooth, natural focus effects in foreground and background. This advanced STF (Smooth Transition Focus) telephoto lens incorporates an apodization optical element that distributes light rays to create smooth, aesthetically pleasing out-of-focus backgrounds that make sharp-focus subjects stand out more vividly. Mounted on the Sony® α (alpha) DSLR-A100 camera, this lens provides a 200mm focal length (35mm equivalent).
Smooth Transmission Focus:
While subjects remain in sharp focus, out-of-focus backgrounds or foregrounds are blurred smoothly and evenly with gradation that thickens toward the edges of the frame for a pleasing aesthetic effect.
Transmissive Brightness:
After light passes through the apodization element, the lens aperture of f2.8 yields a T (transmissive brightness) equivalent of 4.5; a manual aperture ring can adjust T setting from 4.5 to 6.7.
Wide Focus Ring:
The dedicated manual focusing system is controlled by a wide focus ring that’s comfortable to hold and gives you a solid, hands-on feel for pinpoint focusing of your subject.
Circular Aperture:
Because aperture blades form a near circle at the wide openings used for low-light shots, spot-light sources have a pleasing circular defocused effect.
Sony SAL135F28, Black, 2.83" (7.2 cm), 25.7 oz (730 g), 0.25X
Sony SAL135F28. Product color: Black. Filter size: 2.83" (7.2 cm), Weight: 25.7 oz (730 g). Magnification: 0.25X
The Sony 135 f/2.8 [T4.5] STF SAL-135F28 is a unique lens, which produces a very soft and smooth background blur and for some people that might be enough to justify purchase of the lens. However, it has some downsides. As a portrait lens its a bit lon... 
