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Canon 24mm f/2.8 IS — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published JP2020-190696A optical prescription (11 elements in 9 groups, 1 aspherical) with a 8.6 mm entrance pupil and 0.2 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | JP2020-190696A · 11 elements in 9 groups (1 aspherical) | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 8.6 mm (at f/2.8) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 63% at f/2.8 (≥86% from f/5.6) · -1.0 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 75° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 0.99 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 23.6 mm (-1.6%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 44 cm (82 cm – 1.25 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.2 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Canon 24mm f/2.8 IS produce?
Wide open at f/2.8, the Canon 24mm f/2.8 IS has a 8.6 mm entrance pupil (24 mm ÷ 2.8) and 63% bokeh roundness in the 90% corner (-1.0 EV corner falloff, reaching ≥86% roundness from f/5.6). In an upper-body portrait at 0.99 m, the sharp depth-of-field zone spans 44 cm (82 cm to 1.25 m) with a 75° horizontal background angle of view.
Does the Canon 24mm f/2.8 IS show focus breathing at portrait distance?
Based on patent JP2020-190696A, tracing the focusing group at 0.99 m gives an effective framing focal length of 23.6 mm (-1.6% vs. the nominal 24 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Canon 24mm f/2.8 IS?
The patent prescription (JP2020-190696A) specifies 11 lens elements in 9 groups with 1 aspherical surfaces. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Canon 28mm f/1.8 USM
- Canon 20mm f/2.8 USM
- 24mm vs 35mm focal length comparison
- 24mm vs 50mm focal length comparison
- 28mm vs 35mm focal length comparison
- 28mm vs 50mm focal length comparison
Compare with similar portrait lenses
- Sony FE 24mm F2.8 G
- Canon FD 24mm f/2.8 S.S.C.
- Nikon 24mm f/2.8 AI-s
- Leica ELMARIT-M 24mm f/2.8 ASPH
- Nikon 24mm f/3.5 PC-E FX
- Sony E 30mm F3.5 Macro
Also see: depth of field, bokeh, crop factor, lens compression.