The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Nikon 105mm f2D DC 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 Nikon 105mm f2D DC with a length of 111mm, is 92mm shorter. Besides being longer, the Sigma 120-400mm F4.5-5.6 DG OS HSM also has a larger diameter of 92mm compared to the Nikon 105mm f2D DC's 79mm 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. Nikon 105mm f2D DC weighs 640g, which means it is 1000g (60%) lighter than the Sigma 120-400mm F4.5-5.6 DG OS HSM which has a weight of 1640g.
Filter Threads
The Nikon 105mm f2D DC has a filter size of 72mm 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 72mm filters that we recommend you to consider for the Nikon 105mm f2D DC:
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 Nikon 105mm f2D DC and the Sigma 120-400mm F4.5-5.6 DG OS HSM has the same Nikon F (FX) lens mount. Some of the latest released cameras that are compatible with the Nikon F (FX) lenses are Nikon D6, Nikon D780 and Nikon D3500.
Sigma 120-400mm F4.5-5.6 DG OS HSM is also available in Canon EF and Sigma SA mounts.
Focal Range
Nikon 105mm f2D DC is a prime lens with fixed focal lenght of 105mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
157.5mm.
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 . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 180 - 600mm.