The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Leica SL 100mm F2.8 and the Panasonic S 85mm F1.8 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. Leica SL 100mm F2.8 is the longer of the two lenses at 137mm. The Panasonic S 85mm F1.8 with a length of 82mm, is 55mm shorter. Besides being longer, the Leica SL 100mm F2.8 also has a larger diameter of 77mm compared to the Panasonic S 85mm F1.8's 74mm 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. Panasonic S 85mm F1.8 weighs 355g, 55% (446g) lighter than the Leica SL 100mm F2.8's weight of 801g.
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
Both the Leica SL 100mm F2.8 and the Panasonic S 85mm F1.8 have the same Filter thread size of 67mm.
Below are links to the 67mm filters that we recommend you to consider for these lenses:
Lens Mounts
Both the Leica SL 100mm F2.8 and the Panasonic S 85mm F1.8 has the same Leica L lens mount. Some of the latest released cameras that are compatible with the Leica L lenses are Leica SL3-P, Panasonic S1 II and Panasonic S1 IIE.
Focal Range
Leica SL 100mm F2.8 is a prime lens with fixed focal lenght of 100mm.
On the other hand, the Panasonic S 85mm F1.8 is a prime lens with fixed focal lenght of 85mm.