The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Leica APO-SL 90mm F2 ASPH and the Sigma 85mm F1.4 DG HSM A 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 85mm F1.4 DG HSM A is the longer of the two lenses at 126mm. The Leica APO-SL 90mm F2 ASPH with a length of 102mm, is 24mm shorter. Besides being longer, the Sigma 85mm F1.4 DG HSM A also has a larger diameter of 95mm compared to the Leica APO-SL 90mm F2 ASPH's 73mm diameter.
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Below you can find a scaled side-by-side image of Leica APO-SL 90mm F2 ASPH and Sigma 85mm F1.4 DG HSM A to get a better idea of how their sizes compare in real life.
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. Leica APO-SL 90mm F2 ASPH weighs 700g, which means it is 430g (38%) lighter than the Sigma 85mm F1.4 DG HSM A which has a weight of 1130g.
Below you can find the dimension and weight table of the Telephoto Prime Lenses in Leica L Mount for size comparison purposes.
Telephoto Lenses in Leica L Mount for Size Comparison
Filter Threads
The Leica APO-SL 90mm F2 ASPH has a filter size of 67mm whereas the Sigma 85mm F1.4 DG HSM A has a 86mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Leica APO-SL 90mm F2 ASPH:
And these are the 86mm filters that we recommend for the Sigma 85mm F1.4 DG HSM A:
Lens Mounts
Both the Leica APO-SL 90mm F2 ASPH and the Sigma 85mm F1.4 DG HSM A has the same Leica L lens mount. Some of the latest released cameras that are compatible with the Leica L lenses are Leica SL3, Panasonic S5 II and Panasonic S5 II X.
Focal Range
Leica APO-SL 90mm F2 ASPH is a prime lens with fixed focal lenght of 90mm.
On the other hand, the Sigma 85mm F1.4 DG HSM A is a prime lens with fixed focal lenght of 85mm.