Canon EF 50mm f/1.8 STM vs RF 45mm F/1.2 STM: Which Prime?
By Cameriz Limited | Published: 2026-11-02
Category: Comparisons
Compare the Canon EF 50mm f/1.8 STM and RF 45mm F/1.2 STM on mount, aperture, and price to pick the right prime for your Canon kit.
Quick answer
Choose the Canon EF 50mm f/1.8 STM if you shoot a DSLR or want the lowest-cost way into a fast prime; choose the Canon RF 45mm F/1.2 STM if you shoot a Canon RF-mount mirrorless body and need the extra light from its f/1.2 aperture for portraits and low-light work.
Mount and body compatibility decide more than specs
The EF 50mm f/1.8 STM uses the older EF mount, so it fits Canon DSLRs directly. On an RF-mount mirrorless body it needs an EF-to-RF adapter, which adds bulk and an extra item to carry. The RF 45mm F/1.2 STM is built for the RF mount and mounts directly to RF bodies without an adapter.
If you own both DSLR and mirrorless Canon gear, the EF lens is the more flexible option because it can move between systems with the right adapter. If your kit is RF-only, the native RF lens removes that friction entirely.
Aperture and focal length change how you shoot
The RF 45mm F/1.2 STM opens to f/1.2, which lets in more light than the EF lens's f/1.8 maximum aperture. That matters in dim venues and for separating a portrait subject from the background. The 45mm focal length sits slightly wider than 50mm, so it frames a little more of the scene at the same distance.
The EF 50mm f/1.8 STM is the classic nifty fifty: a compact, lightweight prime that is easy to leave on the camera all day. Its f/1.8 aperture still gives useful low-light headroom and shallow depth of field, just not as much as f/1.2.
Price and value trade-off
At catalog prices of USD 86.10 for the EF 50mm f/1.8 STM and USD 203.28 for the RF 45mm F/1.2 STM, the EF lens costs less than half as much. The RF lens asks more money for its wider aperture and native RF mount.
Neither lens is the obvious winner on value alone: the EF lens is the budget entry point, while the RF lens is the spend for low-light speed and direct RF fit. Decide which of those you actually need before comparing price tags.
Key trade-offs at a glance
- Mount: EF mount fits DSLRs directly; RF mount fits mirrorless bodies directly. Using the EF lens on an RF body requires an EF-to-RF adapter. Check your camera mount first; an adapter adds cost and bulk to the EF path.
- Maximum aperture: The RF lens opens to f/1.2 versus f/1.8 on the EF lens, giving the RF more light and shallower depth of field. Pick f/1.2 only if you regularly shoot in dim light or want very blurred backgrounds.
- Price: The EF 50mm f/1.8 STM is listed at USD 86.10 and the RF 45mm F/1.2 STM at USD 203.28. Set a budget before choosing; the aperture and mount differences are what the extra spend buys.
Product facts
- Canon EF 50mm f/1.8 STM Lens: Compact prime with an f/1.8 maximum aperture and a 50mm focal length. It keeps a camera bag light and still gives a bright aperture for everyday shooting and portraits.
Canon EF 50mm f/1.8 STM Lens - Canon RF 45mm F/1.2 STM Lens: RF-mount prime with a 45mm focal length and an f/1.2 maximum aperture. It mounts directly to RF bodies and gathers more light for low-light work and stronger background blur.
Canon RF 45mm F/1.2 STM Lens
Which prime fits your kit?
Best for
- DSLR shooters who want a lightweight, low-cost fast prime
- Photographers who split time between EF and RF bodies and can use an adapter
Not for
- RF-mount shooters who want to avoid adapters and need the brightest aperture available
- Buyers who prioritize a native mirrorless mount over the lowest price
