The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Samyang 50mm F1.4 AS UMC 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 Samyang 50mm F1.4 AS UMC with a length of 75mm, is 56mm shorter. Besides being longer, the Sigma 40mm F1.4 DG HSM A also has a larger diameter of 88mm compared to the Samyang 50mm F1.4 AS UMC's 82mm 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 Sony E Mount for size comparison purposes.
Standard Lenses in Sony E Mount for Size Comparison
Filter Threads
The Samyang 50mm F1.4 AS UMC 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 Samyang 50mm F1.4 AS UMC:
And these are the 82mm filters that we recommend for the Sigma 40mm F1.4 DG HSM A:
Lens Mounts
Both the Samyang 50mm F1.4 AS UMC and the Sigma 40mm F1.4 DG HSM A has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony A9 III, Sony A7C Mark II and Sony A7CR.
Samyang 50mm F1.4 AS UMC is also available in Canon EF , Nikon F (FX), Pentax KAF and Sony Alpha mounts.
Sigma 40mm F1.4 DG HSM A is also available in Canon EF , Nikon F (FX), Sigma SA and Leica L mounts.
Focal Range
Samyang 50mm F1.4 AS UMC is a prime lens with fixed focal lenght of 50mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
75mm.
On the other hand, the Sigma 40mm F1.4 DG HSM A is a prime lens with fixed focal lenght of 40mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 60mm.