The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon RF 45mm F1.2 and the Sigma 56mm F1.4 C 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 45mm F1.2 is the longer of the two lenses at 75mm. The Sigma 56mm F1.4 C with a length of 60mm, is 15mm shorter. Besides being longer, the Canon RF 45mm F1.2 also has a larger diameter of 78mm 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, 19% (66g) lighter than the Canon RF 45mm F1.2's weight of 346g.
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 Canon RF 45mm F1.2 has a filter size of 67mm whereas the Sigma 56mm F1.4 C has a 55mm 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 Canon RF 45mm F1.2:
And these are the 55mm filters that we recommend for the Sigma 56mm F1.4 C:
Lens Mounts
Both the Canon RF 45mm F1.2 and the Sigma 56mm F1.4 C has the same Canon RF lens mount. Some of the latest released cameras that are compatible with the Canon RF lenses are Canon R6 V, Canon R6 III and Canon C50.
Sigma 56mm F1.4 C is also available in Fujifilm X and Nikon Z mounts.
Focal Range
Canon RF 45mm F1.2 is a prime lens with fixed focal lenght of 45mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
72mm.
On the other hand, the 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.
