The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 12mm f1.4 and the Canon RF-S 10-18mm F4.5-6.3 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 12mm f1.4 is the longer of the two lenses at 67mm. The Canon RF-S 10-18mm F4.5-6.3 with a length of 45mm, is 22mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 69mm.
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. Canon RF-S 10-18mm F4.5-6.3 weighs 150g, 40% (100g) lighter than the Sigma 12mm f1.4's weight of 250g.
Filter Threads
The Sigma 12mm f1.4 has a filter size of 62mm whereas the Canon RF-S 10-18mm F4.5-6.3 has a 49mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 62mm filters that we recommend you to consider for the Sigma 12mm f1.4:
And these are the 49mm filters that we recommend for the Canon RF-S 10-18mm F4.5-6.3:
Lens Mounts
Both the Sigma 12mm f1.4 and the Canon RF-S 10-18mm F4.5-6.3 has the same Canon RF lens mount. Some of the latest released cameras that are compatible with the Canon RF lenses are RED Komodo-X 6K, RED Komodo 6K and Canon EOS C70.
Sigma 12mm f1.4 is also available in the Sony E and Fujifilm X mounts.
Focal Range
Sigma 12mm f1.4 is a prime lens with fixed focal lenght of 12mm which has an effective (full-frame 35mm equivalent) focal range of
18mm when used on a APS-C / DX format camera.
On the other hand, the Canon RF-S 10-18mm F4.5-6.3 has a focal range of 10-18mm and 1.8X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 16-28.8mm when used on a APS-C / DX format camera.
