Canon RF 50mm f/1.8 STM Lens vs Canon RF-S 18-45mm f/4.5-6.3 IS STM
The bottom line
These cover different focal lengths — the Canon RF 50mm f/1.8 STM Lens is 50mm, the Canon RF-S 18-45mm f/4.5-6.3 IS STM is 18-45mm — so they're not really substitutes. Pick by the field of view you actually need: the Canon RF 50mm f/1.8 STM Lens for short-telephoto / portrait, the Canon RF-S 18-45mm f/4.5-6.3 IS STM for standard.
Choose the Canon RF 50mm f/1.8 STM Lens if…
- ✓You want more light and background blur — f/1.8 is faster than f/4.5, better for low light and subject separation.
- ✓You prefer a fast, compact single focal length — a 50mm prime over a zoom.
Choose the Canon RF-S 18-45mm f/4.5-6.3 IS STM if…
- ✓You shoot wide — it starts at 18mm vs 50mm for landscapes, interiors and architecture.
- ✓You want one-lens flexibility — a 18-45mm zoom covers what the fixed 50mm can't reframe.
- ✓You shoot handheld or on an unstabilised body — it has optical stabilisation, the other doesn't.
- ✓You use filters or shoot video — internal zoom keeps length and balance constant.
Where they differ
- ›Aperture: the Canon RF 50mm f/1.8 STM Lens opens to f/1.8 vs the Canon RF-S 18-45mm f/4.5-6.3 IS STM's f/4.5 — more light and shallower depth-of-field.
- ›Focal range: Canon RF 50mm f/1.8 STM Lens is 50mm, Canon RF-S 18-45mm f/4.5-6.3 IS STM is 18-45mm — different framing and reach.
- ›Type: the Canon RF-S 18-45mm f/4.5-6.3 IS STM is a zoom (flexible framing), the Canon RF 50mm f/1.8 STM Lens a prime (one focal length, usually brighter and lighter).
- ›Stabilisation: only the Canon RF-S 18-45mm f/4.5-6.3 IS STM has optical stabilisation — steadier handheld shots, especially on bodies without IBIS.
Frequently asked
Is the Canon RF 50mm f/1.8 STM Lens or the Canon RF-S 18-45mm f/4.5-6.3 IS STM better?
These cover different focal lengths — the Canon RF 50mm f/1.8 STM Lens is 50mm, the Canon RF-S 18-45mm f/4.5-6.3 IS STM is 18-45mm — so they're not really substitutes. Pick by the field of view you actually need: the Canon RF 50mm f/1.8 STM Lens for short-telephoto / portrait, the Canon RF-S 18-45mm f/4.5-6.3 IS STM for standard.
Who should choose the Canon RF 50mm f/1.8 STM Lens?
Choose the Canon RF 50mm f/1.8 STM Lens if you want more light and background blur — f/1.8 is faster than f/4.5, better for low light and subject separation. Choose it if you prefer a fast, compact single focal length — a 50mm prime over a zoom.
Who should choose the Canon RF-S 18-45mm f/4.5-6.3 IS STM?
Choose the Canon RF-S 18-45mm f/4.5-6.3 IS STM if you shoot wide — it starts at 18mm vs 50mm for landscapes, interiors and architecture. Choose it if you want one-lens flexibility — a 18-45mm zoom covers what the fixed 50mm can't reframe. Choose it if you shoot handheld or on an unstabilised body — it has optical stabilisation, the other doesn't. Choose it if you use filters or shoot video — internal zoom keeps length and balance constant.
What is the main difference between the Canon RF 50mm f/1.8 STM Lens and the Canon RF-S 18-45mm f/4.5-6.3 IS STM?
Aperture: the Canon RF 50mm f/1.8 STM Lens opens to f/1.8 vs the Canon RF-S 18-45mm f/4.5-6.3 IS STM's f/4.5 — more light and shallower depth-of-field.
| Product | ||
|---|---|---|
| Optical Design | ||
| Focal Length | 50mm | 18-45mm |
| Lens Type | Prime | Zoom |
| Optical Elements | 6 | 11 |
| Optical Groups | 5 | 9 |
| Aperture & Iris | ||
| Maximum Aperture | f/1.8 | f/4.5 |
| Minimum Aperture | f/22 | f/22 |
| Aperture Blades | 7 | 7 |
| Rounded Aperture | Yes | Yes |
| Coverage & Angle | ||
| Format Coverage | Full-Frame | APS-C |
| Lens Mount | Canon RF | Canon RF |
| Angle of View | 46° – 46° | 76° – 35° |
| 35mm Equivalent | − | 29-72mm |
| Focus | ||
| Autofocus | Yes | Yes |
| Focus Motor | STM | STM |
| Focus Limiter | No | No |
| AF/MF Switch | No | No |
| Min Focus Distance | 30 cm | 25 cm |
| Max Magnification | 0.25x | 0.29x |
| Stabilization & Video | ||
| Optical Stabilization | No | Yes |
| Aperture Ring | No | No |
| Declickable Aperture | No | No |
| Parfocal | No | No |
| Internal Zoom | No | Yes |
| General | ||
| Price (MSRP) | $239 | $299 |
| Filter Size | 43mm | 49mm |
| Diameter | 69mm | 68.1mm |
| Length | 40mm | 44.8mm |
| Weight | 160g (5.6 oz) | 149g (5.3 oz) |
| Weather Sealed | No | No |
| Tripod Collar | No | No |
