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 Tamron 45mm F1.8 Di VC USD 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 50mm F1.4 DG HSM A is the longer of the two lenses at 100mm. The Tamron 45mm F1.8 Di VC USD with a length of 92mm, is 8mm shorter. Besides being longer, the Sigma 50mm F1.4 DG HSM A also has a larger diameter of 85mm compared to the Tamron 45mm F1.8 Di VC USD's 80mm 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. Tamron 45mm F1.8 Di VC USD weighs 520g, 36% (295g) lighter than the Sigma 50mm F1.4 DG HSM A's weight of 815g.
Below you can find the dimension and weight table of the Standard Prime Lenses in Sony Alpha Mount for size comparison purposes.
Standard Lenses in Sony Alpha Mount for Size Comparison
Filter Threads
The Sigma 50mm F1.4 DG HSM A has a filter size of 77mm whereas the Tamron 45mm F1.8 Di VC USD has a 67mm 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 67mm filters that we recommend for the Tamron 45mm F1.8 Di VC USD:
Lens Mounts
Both the Sigma 50mm F1.4 DG HSM A and the Tamron 45mm F1.8 Di VC USD has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A99 II, Sony A68 and Sony A77 II.
Sigma 50mm F1.4 DG HSM A is also available in Canon EF , Sigma SA, Nikon F (FX) and Leica L mounts.
Tamron 45mm F1.8 Di VC USD is also available in Canon EF and Nikon F (FX) mounts.
Focal Range
Sigma 50mm F1.4 DG HSM A 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 Tamron 45mm F1.8 Di VC USD is a prime lens with fixed focal lenght of 45mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 67.5mm.