The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 50mm F1.4 DG HSM A and the Sigma 40mm 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 40mm F1.4 DG HSM A is the longer of the two lenses at 131mm. The Sigma 50mm F1.4 DG HSM A with a length of 100mm, is 31mm shorter. Besides being longer, the Sigma 40mm F1.4 DG HSM A also has a larger diameter of 88mm compared to the Sigma 50mm F1.4 DG HSM A's 85mm 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.
Below you can find the dimension and weight table of the Standard Prime Lenses in Leica L Mount for size comparison purposes.
Standard Lenses in Leica L Mount for Size Comparison
Filter Threads
The Sigma 50mm F1.4 DG HSM A has a filter size of 77mm whereas the Sigma 40mm F1.4 DG HSM A 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 77mm filters that we recommend you to consider for the Sigma 50mm F1.4 DG HSM A:
And these are the 82mm filters that we recommend for the Sigma 40mm F1.4 DG HSM A:
Lens Mounts
Both the Sigma 50mm F1.4 DG HSM A and the Sigma 40mm 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.
Sigma 50mm F1.4 DG HSM A is also available in Canon EF , Sony Alpha, Sigma SA and Nikon F (FX) mounts.
Sigma 40mm F1.4 DG HSM A is also available in Canon EF , Nikon F (FX), Sigma SA and Sony E mounts.
Focal Range
Sigma 50mm F1.4 DG HSM A is a prime lens with fixed focal lenght of 50mm.
On the other hand, the Sigma 40mm F1.4 DG HSM A is a prime lens with fixed focal lenght of 40mm.