Circular Aperture
When changing your aperture to defocus the background, the light sources appear blurred. This bokeh' effect of the blurred background can be enhanced with circular aperture blades used in this lens. Conventional aperture blades have flat sides creating unappealing polygonal shaped defocussed points of light. α lenses overcome this problem through a unique design that keeps the aperture almost perfectly circular from its wide-open setting to when it is closed by 2 stops. Smoother, more natural defocusing can be obtained as a result.
ED (Extra-low Dispersion) glass
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. ED glass dramatically reduces chromatic aberration at telephoto ranges, and provides superior contrast across the entire image, even at large aperture settings. Super ED glass provides enhanced compensation for chromatic aberration.
Focus hold button
Once you've 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 camera's custom settings.
Rear focusing elements
Only the rear groups of the optical system move to focus the lens, which allows for speedy AF operation and a shorter minimum focusing distance. Since the front of the lens does not rotate, operability is improved when shooting with a polarizing filter attached.
SSM (Super Sonic wave Motor)
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 that feature SSM also include a position-sensitive detector to directly detect the amount of lens rotation, a factor that improves AF precision overall.
Focus range limiter
This function allows you to set a limit on the focusing range which can save you time during AF 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 (as pictured). In the SAL70200G, the limit is set on far ranges only. In the SAL300F28G, focusing can be limited either to a far range or to a range that you specify yourself.
Distance encoder
The distance encoder plays an integral part in ADI flash metering, which delivers high precision flash metering that is unaffected by the reflectance of subjects or backgrounds. The distance encoder is a lens component that directly detects the position of the focusing mechanism, and sends a signal to the CPU in order to measure distance to the subject. During flash photography, this data is very useful in calculating how much flash output is appropriate to the scene.
0.25x maximum magnification.
0.25x maximum magnification.
In-Camera Image Stabilization.
Works with the SteadyShot® image stabilization built into Sony α DSLRs.
Smooth Manual Focusing.
An easy-grip focus ring on the lens barrel gives you a solid "hands-on" feel in manual focusing.
Multi-Element Design.
The SAL70300G incorporates 16 elements in 11 groups for high optical precision from the center of the image all the way to the corners.
Circular Aperture.
Because the aperture blades form a near circle at the wide openings used for low-light shots, spot-light sources have a pleasing circular defocused effect. The lens features nine aperture blades.
Supplied accessories.
Supplied accessories. Carrying case, lens caps and petal shaped lens hood.
