The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony 70-400mm F4-5.6 G SSM II and the Sigma 120-400mm F4.5-5.6 DG 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. Sigma 120-400mm F4.5-5.6 DG HSM is the longer of the two lenses at 203mm. The Sony 70-400mm F4-5.6 G SSM II with a length of 196mm, is 7mm shorter. On the other hand, the Sony 70-400mm F4-5.6 G SSM II has a larger diameter of 95mm compared to the Sigma 120-400mm F4.5-5.6 DG HSM's 92mm 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. Sony 70-400mm F4-5.6 G SSM II weighs 1500g, which means it is 140g (8%) lighter than the Sigma 120-400mm F4.5-5.6 DG HSM which has a weight of 1640g.
Filter Threads
Both the Sony 70-400mm F4-5.6 G SSM II and the Sigma 120-400mm F4.5-5.6 DG HSM have the same Filter thread size of 77mm.
Below are links to the 77mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Sony 70-400mm F4-5.6 G SSM II has the Sony Alpha lens mount whereas the Sigma 120-400mm F4.5-5.6 DG HSM has the Pentax KAF3 lens mount. Some of the latest released cameras that are compatible with these mounts are Sony A99 II, Sony A68 and Sony A77 II for the Sony Alpha Mount and Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF3 Mount.
Sigma 120-400mm F4.5-5.6 DG HSM is also available in Sony Alpha mount.
Focal Range
Sony 70-400mm F4-5.6 G SSM II has a focal range of 70-400mm and
5.7X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
105 - 600mm.
On the other hand, the Sigma 120-400mm F4.5-5.6 DG HSM has a focal range of 120-400mm and 3.3X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 180 - 600mm.
