The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony FE 135mm F1.8 GM and the Sigma 10-20mm F3.5 EX DC HSM for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is a crucial factor to consider when comparing two lenses. Sony FE 135mm F1.8 GM is the longer of the two lenses at 127mm. The Sigma 10-20mm F3.5 EX DC HSM with a length of 88mm, is 39mm shorter. Besides being longer, the Sony FE 135mm F1.8 GM also has a larger diameter of 90mm compared to the Sigma 10-20mm F3.5 EX DC HSM's 87mm diameter.
The weight of a lens is equally significant as its external dimensions, particularly if you intend to handhold your camera and lens combination for extended periods. Sigma 10-20mm F3.5 EX DC HSM weighs 520g, 45% (430g) lighter than the Sony FE 135mm F1.8 GM's weight of 950g.
Filter Threads
Both the Sony FE 135mm F1.8 GM and the Sigma 10-20mm F3.5 EX DC HSM have the same Filter thread size of 82mm.
Below are links to the 82mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Sony FE 135mm F1.8 GM has the Sony E lens mount whereas the Sigma 10-20mm F3.5 EX DC HSM has the Sigma SA lens mount. Some of the latest released cameras that are compatible with these mounts are Sony FX5, Sony A7R VI and Sony A7 V for the Sony E Mount and Sigma SD1 Merrill, Sigma SD1 and for the Sigma SA Mount.
Sigma 10-20mm F3.5 EX DC HSM is also available in Canon EF , Pentax KAF3, Sony Alpha and Nikon F (DX) mounts.
Focal Range
Sony FE 135mm F1.8 GM is a prime lens with fixed focal lenght of 135mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
202.5mm.
On the other hand, the Sigma 10-20mm F3.5 EX DC HSM has a focal range of 10-20mm and 2.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 15-30mm when used on a APS-C / DX format camera.
