The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 50-100mm F1.8 A and the Sigma 120-400mm F4.5-5.6 DG OS 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 OS HSM is the longer of the two lenses at 203mm. The Sigma 50-100mm F1.8 A with a length of 171mm, is 32mm shorter. On the other hand, the Sigma 50-100mm F1.8 A has a larger diameter of 94mm compared to the Sigma 120-400mm F4.5-5.6 DG OS 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. Sigma 50-100mm F1.8 A weighs 1490g, which means it is 150g (9%) lighter than the Sigma 120-400mm F4.5-5.6 DG OS HSM which has a weight of 1640g.
Filter Threads
The Sigma 50-100mm F1.8 A has a filter size of 82mm whereas the Sigma 120-400mm F4.5-5.6 DG OS HSM has a 77mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 82mm filters that we recommend you to consider for the Sigma 50-100mm F1.8 A:
And these are the 77mm filters that we recommend for the Sigma 120-400mm F4.5-5.6 DG OS HSM:
Lens Mounts
Both the Sigma 50-100mm F1.8 A and the Sigma 120-400mm F4.5-5.6 DG OS HSM has the same Sigma SA lens mount. Some of the latest released cameras that are compatible with the Sigma SA lenses are Sigma SD1 Merrill, Sigma SD1 and .
Sigma 50-100mm F1.8 A is also available in Canon EF and Nikon F (DX) mounts.
Sigma 120-400mm F4.5-5.6 DG OS HSM is also available in Canon EF and Nikon F (FX) mounts.
Focal Range
Sigma 50-100mm F1.8 A has a focal range of 50-100mm and
2.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
75-150mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 120-400mm F4.5-5.6 DG OS HSM has a focal range of 120-400mm and 3.3X zoom ratio .