The 28-75mm is a Di III series zoom and this is Tamron’s designation for lenses intended for full-35mm format mirrorless cameras. Stepping motors are becoming more frequently used for autofocusing systems because they’re not only very quiet, but provide the smoothness which is especially important when shooting video.

Photo: Tamron

The Tamron lens supports Sony’s ‘DMF’ (Direct Manual Focus) function which provides a full-time manual override of the autofocusing. It also supports Sony’s in-camera corrections for vignetting, chromatic aberrations and distortion.

The minimum focusing distance is 19 centimetres at 28mm and 39 centimetres at 75mm which gives a maximum reproduction ratio of 1:4.. It measures 117.8 mm and weighs in at 550 grams.

The FE mount 28-75mm f2.8 Di III RXD zoom (a.k.a. Model A036) features a weather-sealed external construction with a fluorine coating on the exposed surface of the front element to help better repel moisture and grease. The optical construction comprises 15 elements in 12 groups which includes one XLD (eXtra Low Dispersion) type, one LD (Low Dispersion) type and three aspherical elements – one glass-moulded type and two hybrid types. Collectively, these special elements correct for both distortion and chromatic aberrations. The new lens also

Has Tamron’s BBAR (Broad Band Anti Reflection) multi-coating to correct for both ghosting and flare.

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