The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 120-400mm F4.5-5.6 DG HSM and the Sony 70-400mm F4-5.6 G SSM II 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, 8% (140g) lighter than the Sigma 120-400mm F4.5-5.6 DG HSM's weight of 1640g.
Below you can find the dimension and weight table of the Telephoto Zoom Lenses in Sony Alpha Mount for size comparison purposes.
Super Telephoto Lenses in Sony Alpha Mount for Size Comparison
Filter Threads
Both the Sigma 120-400mm F4.5-5.6 DG HSM and the Sony 70-400mm F4-5.6 G SSM II 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
Both the Sigma 120-400mm F4.5-5.6 DG HSM and the Sony 70-400mm F4-5.6 G SSM II has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A99 II, Sony A68 and Sony A77 II.
Sigma 120-400mm F4.5-5.6 DG HSM is also available in the Pentax KAF3 mount.
Focal Range
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.
On the other hand, the 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.
