The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 56mm F1.4 C and the Canon RF 50mm F1.2L USM 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. Canon RF 50mm F1.2L USM is the longer of the two lenses at 108mm. The Sigma 56mm F1.4 C with a length of 60mm, is 48mm shorter. Besides being longer, the Canon RF 50mm F1.2L USM also has a larger diameter of 90mm compared to the Sigma 56mm F1.4 C's 67mm 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. Sigma 56mm F1.4 C weighs 280g, which means it is 670g (70%) lighter than the Canon RF 50mm F1.2L USM which has a weight of 950g.
Below you can find the dimension and weight table of the Standard Prime Lenses in Canon RF Mount for size comparison purposes.
Standard Lenses in Canon RF Mount for Size Comparison
Filter Threads
The Sigma 56mm F1.4 C has a filter size of 55mm whereas the Canon RF 50mm F1.2L USM has a 77mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 55mm filters that we recommend you to consider for the Sigma 56mm F1.4 C:
And these are the 77mm filters that we recommend for the Canon RF 50mm F1.2L USM:
Lens Mounts
Both the Sigma 56mm F1.4 C and the Canon RF 50mm F1.2L USM has the same Canon RF lens mount. Some of the latest released cameras that are compatible with the Canon RF lenses are Canon R50 V, Canon R100 and Canon R50.
Sigma 56mm F1.4 C is also available in the Fujifilm X and Nikon Z mounts.
Focal Range
Sigma 56mm F1.4 C is a prime lens with fixed focal lenght of 56mm which has an effective (full-frame 35mm equivalent) focal range of
89.6mm when used on a APS-C / DX format camera.
On the other hand, the Canon RF 50mm F1.2L USM is a prime lens with fixed focal lenght of 50mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 80mm.