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Canon 50mm f/2.5 EF Macro — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published JP S63-179308A optical prescription (9 elements in 8 groups) with a 20.0 mm entrance pupil and 0.23 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | JP S63-179308A · 9 elements in 8 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 20.0 mm (at f/2.5) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 72% at f/2.5 (≥86% from f/4) · -0.6 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 39° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 2.01 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 50.8 mm (+1.5%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 36 cm (1.85 m – 2.21 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.23 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Canon 50mm f/2.5 EF Macro produce?
Wide open at f/2.5, the Canon 50mm f/2.5 EF Macro has a 20.0 mm entrance pupil (50 mm ÷ 2.5) and 72% bokeh roundness in the 90% corner (-0.6 EV corner falloff, reaching ≥86% roundness from f/4). In an upper-body portrait at 2.01 m, the sharp depth-of-field zone spans 36 cm (1.85 m to 2.21 m) with a 39° horizontal background angle of view.
Does the Canon 50mm f/2.5 EF Macro show focus breathing at portrait distance?
Based on patent JP S63-179308A, tracing the focusing group at 2.01 m gives an effective framing focal length of 50.8 mm (+1.5% vs. the nominal 50 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Canon 50mm f/2.5 EF Macro?
The patent prescription (JP S63-179308A) specifies 9 lens elements in 8 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Canon EF 50mm f/1.4 USM
- Canon EF 50mm f/1.8 II
- 24mm vs 50mm focal length comparison
- 28mm vs 50mm focal length comparison
- 35mm vs 50mm focal length comparison
- 40mm vs 50mm focal length comparison
Compare with similar portrait lenses
- Sony FE 50mm F2.8 Macro
- Sony AF 50mm F2.8 Macro
- Sony MD 50mm F2
- Nikon 50mm f/2
- Leica ELMAR-M 50mm f/2.8
- Nikon NIKKOR Z 40mm f/2
Also see: depth of field, bokeh, crop factor, lens compression.