The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon RF-S 18-45mm f4.5-6.3 IS and the Canon RF 50mm F1.8 STM 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-S 18-45mm f4.5-6.3 IS is the longer of the two lenses at 44mm. The Canon RF 50mm F1.8 STM with a length of 41mm, is 3mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 69mm.
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Below you can find a scaled side-by-side image of Canon RF-S 18-45mm f4.5-6.3 IS and Canon RF 50mm F1.8 STM to get a better idea of how their sizes compare in real life.
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 18-45mm f4.5-6.3 IS weighs 130g, which means it is 30g (18%) lighter than the Canon RF 50mm F1.8 STM which has a weight of 160g.
Filter Threads
The Canon RF-S 18-45mm f4.5-6.3 IS has a filter size of 49mm whereas the Canon RF 50mm F1.8 STM has a 43mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 49mm filters that we recommend you to consider for the Canon RF-S 18-45mm f4.5-6.3 IS:
And these are the 43mm filters that we recommend for the Canon RF 50mm F1.8 STM:
Lens Mounts
Both the Canon RF-S 18-45mm f4.5-6.3 IS and the Canon RF 50mm F1.8 STM has the same Canon RF lens mount. Some of the latest released cameras that are compatible with the Canon RF lenses are Canon R100, Canon R50 and Canon R10.
Focal Range
Canon RF-S 18-45mm f4.5-6.3 IS has a focal range of 18-45mm and
2.5X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
28.8-72mm when used on a APS-C / DX format camera.
On the other hand, the Canon RF 50mm F1.8 STM 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.