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Canon RF 45mm F1.2 STM — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published US20260194735A1 optical prescription (9 elements in 7 groups, 2 aspherical) with a 37.5 mm entrance pupil and 0.4 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | US20260194735A1 · 9 elements in 7 groups (2 aspherical) | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 37.5 mm (at f/1.2) | Controls distant background blur disc size |
| Upper-Body Working Distance | 1.82 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 44.2 mm (-1.8%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 17 cm (1.73 m – 1.91 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.4 m | Closest focusing distance from the sensor |
Questions
How much background blur does the Canon RF 45mm F1.2 STM produce?
Wide open at f/1.2, the Canon RF 45mm F1.2 STM has a 37.5 mm entrance pupil (45 mm ÷ 1.2). In an upper-body portrait at 1.82 m, the sharp depth-of-field zone spans 17 cm (1.73 m to 1.91 m), while mechanical vignetting and 9 glass elements shape the out-of-focus highlights.
Does the Canon RF 45mm F1.2 STM show focus breathing at portrait distance?
Based on patent US20260194735A1, tracing the focusing group at 1.82 m gives an effective framing focal length of 44.2 mm (-1.8% vs. the nominal 45 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Canon RF 45mm F1.2 STM?
The patent prescription (US20260194735A1) specifies 9 lens elements in 7 groups with 2 aspherical surfaces. The interactive Optical X-Ray above traces rays through every surface in real time.
Head-to-head patent comparisons with Canon RF 45mm F1.2 STM
- Canon RF 45mm F1.2 STM vs. Canon RF 50mm F1.2 L USM
- Canon RF 45mm F1.2 STM vs. Canon RF 50mm F1.8 STM
Related comparisons
- Sony FE 50mm F1.2 GM
- Canon RF 50mm F1.2 L USM
- Nikon NIKKOR Z 50mm f/1.2 S
- Leica NOCTILUX 50mm f/1.2 ASPH
- Sony Planar FE 50mm F1.4 ZA
- Nikon 58mm f/1.4 G FX
Also see: depth of field, bokeh, crop factor, lens compression.