The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Panasonic S 85mm F1.8 and the Leica SL 50mm F1.4 ASPH 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 50mm F1.4 ASPH is the longer of the two lenses at 124mm. The Panasonic S 85mm F1.8 with a length of 82mm, is 42mm shorter. Besides being longer, the Leica SL 50mm F1.4 ASPH also has a larger diameter of 88mm compared to the Panasonic S 85mm F1.8's 74mm diameter.
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Below you can find a scaled side-by-side image of Panasonic S 85mm F1.8 and Leica SL 50mm F1.4 ASPH 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. Panasonic S 85mm F1.8 weighs 355g, which means it is 710g (66%) lighter than the Leica SL 50mm F1.4 ASPH which has a weight of 1065g.
Filter Threads
The Panasonic S 85mm F1.8 has a filter size of 67mm whereas the Leica SL 50mm F1.4 ASPH has a 82mm 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 Panasonic S 85mm F1.8:
And these are the 82mm filters that we recommend for the Leica SL 50mm F1.4 ASPH:
Lens Mounts
Both the Panasonic S 85mm F1.8 and the Leica SL 50mm F1.4 ASPH 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
Panasonic S 85mm F1.8 is a prime lens with fixed focal lenght of 85mm.
On the other hand, the Leica SL 50mm F1.4 ASPH is a prime lens with fixed focal lenght of 50mm.