The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony DT 35mm F1.8 SAM and the Sony 20mm F2.8 for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Sony 20mm F2.8 is the longer of the two lenses at 54mm. The Sony DT 35mm F1.8 SAM with a length of 52mm is 2mm shorter. Besides being longer, the Sony 20mm F2.8 also has a larger diameter of 78mm compared to Sony DT 35mm F1.8 SAM's 70mm diameter.
Weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Sony DT 35mm F1.8 SAM weighs 170g, which means it is 115g (40%) lighter than the Sony 20mm F2.8 which has a weight of 285g.
Below you can find the dimension and weight table of the 'Wideangle Prime Lenses in Sony Alpha Mount for size comparison purposes.
Wideangle Prime Lenses in Sony Alpha Mount for Size Comparison
Both Sony DT 35mm F1.8 SAM and Sony 20mm F2.8 has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A68, Sony A77 II and Sony A58.
Sony DT 35mm F1.8 SAM is a prime lens with fixed focal lenght of 35mm which has an effective (full-frame 35mm equivalent) focal range of 52.5mm when used on a APS-C / DX format camera. Sony 20mm F2.8 is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides an 35mm (FF) equivalent of 30mm.