Sony 50mm f/1.8 DT ( SAL-50F18 ) - Lab Test / Review
Lens Reviews - Sony Alpha/NEX (APS-C)
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Review by Klaus Schroiff, published November 2010

Lens kindly provided by Renwei Chen!


The Sony 50mm f/1.8 DT is one of a series of recently released budget primes for the Sony Alpha system. As a designated DT ("Digital Technology") lens it is compatible with APS-C DSLRs only. Just like most recent DT lenses it features the new SAM ("Smooth Autofocus Motor") so it does no longer depend on the dated AF drive screw system which is still used by many Sony/Zeiss lenses.

The build quality of the lens is average at best. The lens barrel is completely made of plastic and that's including the lens mount. It uses a linear extension system for focusing - the, slightly wobbly, inner lens tube extends slightly during the process. The tiny focus ring at the lens front operates smoothly. It remains coupled to the AF motor in AF mode so it rotates during AF operations. However, the filter ring does not rotate.

The SAM AF drive is reasonably fast but it's not a speed demon either. DMF ("Direct Manual Focusing") is not supported. Manual focusing is a bit delicate due to the tiny focus ring and the rather short focus path (~60 degrees).

Equiv. focal length75 mm (full format equivalent)
Equiv. aperturef/2.7 (full format equivalent, in terms of depth-of-field)
Optical construction6 elements in 5 groups inc. 1(???) ED element
Number of aperture blades7 (rounded)
min. focus distance0.34 m (max. magnification ratio 1:5)
Dimensions70 x 45 mm
Weight170 g
Filter size49 mm (non-rotating)
Other features-

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