Canon RF 45mm F1.2 STM

The Canon RF 45mm F1.2 STM is a standard prime for the RF mount with a very wide f/1.2 aperture. Canon calls it its first f/1.2 lens in the non-professional RF range and its lightest f/1.2 RF lens. It is designed for full-frame EOS R cameras and was announced in November 2025 together with the EOS R6 Mark III. Typical uses are portraits, low-light work and shallow depth of field.

Optical design

The lens has 9 elements in 7 groups with one PMo aspherical element, which Canon says reduces aberrations. The aperture ranges from f/1.2 to f/16 with a 9-blade diaphragm. Canon mentions Super Spectra coating on the lens. The lens keeps a constant length while focusing. Maximum magnification is 0.13x at a minimum focus distance of 0.45 m.

Autofocus and handling

A gear-type STM motor with a magnetic detection system drives the focus. The lens has a dedicated control ring that is separate from the focus ring, which Canon highlights as useful for hybrid photo and video work. There is no optical stabilizer in the lens. Canon also states a durable metal mount.

Build and size

At 346 g, 78 mm in diameter and 75 mm in length, the lens is light for an f/1.2 design but wide in the front. The filter thread is 67 mm. Canon does not list dust or weather sealing on the product page.

Where it fits

Next to the RF 50mm F1.2L USM (950 g in our database) and the RF 50mm F1.4 L VCM (580 g), the 45mm F1.2 STM is clearly the smaller and lighter option, while the L-series lenses offer a different build class. The RF 50mm F1.8 STM is smaller at 160 g and has a 43 mm thread but opens only to f/1.8. A focal length of 45 mm is slightly wider than a classic 50 mm, which suits environmental portraits and everyday scenes.

Pros and cons

Pros

• f/1.2 maximum aperture in a 346 g lens
• Dedicated control ring, separate from the focus ring
• 9 aperture blades
• Constant length while focusing
• Metal mount according to Canon
• Quiet STM autofocus

Cons

• No in-lens stabilizer
• Low maximum magnification of 0.13x
• 67 mm filter thread and a wide front compared with the 50mm F1.8
• No weather sealing listed by Canon
• Not an L-series build

Verdict

The RF 45mm F1.2 STM brings an f/1.2 aperture to enthusiasts at moderate size and weight. It is a good fit for people who want shallow depth of field and low-light capability without moving to an L-series prime. Anyone who needs sealing or a stabilizer will have to look elsewhere in the RF range.