The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon RF-S 7.8mm F4 STM Dual and the Sigma 10-18mm F2.8 DC DN 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. Sigma 10-18mm F2.8 DC DN C is the longer of the two lenses at 64mm. The Canon RF-S 7.8mm F4 STM Dual with a length of 42mm, is 22mm shorter. Besides being longer, the Sigma 10-18mm F2.8 DC DN C also has a larger diameter of 72mm compared to the Canon RF-S 7.8mm F4 STM Dual's 69mm 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. Canon RF-S 7.8mm F4 STM Dual weighs 131g, which means it is 124g (48%) lighter than the Sigma 10-18mm F2.8 DC DN C which has a weight of 255g.
Filter Threads
The Canon RF-S 7.8mm F4 STM Dual has a filter size of 58mm whereas the Sigma 10-18mm F2.8 DC DN C 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 58mm filters that we recommend you to consider for the Canon RF-S 7.8mm F4 STM Dual:
And these are the 67mm filters that we recommend for the Sigma 10-18mm F2.8 DC DN C:
Lens Mounts
Both the Canon RF-S 7.8mm F4 STM Dual and the Sigma 10-18mm F2.8 DC DN C 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 10-18mm F2.8 DC DN C is also available in Sony E , Leica L and Fujifilm X mounts.
Focal Range
Canon RF-S 7.8mm F4 STM Dual is a prime lens with fixed focal lenght of 7.8mm which has an effective (full-frame 35mm equivalent) focal range of
12.8mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 10-18mm F2.8 DC DN C 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.
