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Canon 35mm f/2 IS — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published US20150205081A1 optical prescription (10 elements in 8 groups, 1 aspherical) with a 17.5 mm entrance pupil and 0.24 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | US20150205081A1 · 10 elements in 8 groups (1 aspherical) | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 17.5 mm (at f/2) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 75% at f/2 (≥86% from f/2.8) · -0.6 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 54° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 1.42 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 35.0 mm (-0.0%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 29 cm (1.29 m – 1.58 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.24 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Canon 35mm f/2 IS produce?
Wide open at f/2, the Canon 35mm f/2 IS has a 17.5 mm entrance pupil (35 mm ÷ 2) and 75% bokeh roundness in the 90% corner (-0.6 EV corner falloff, reaching ≥86% roundness from f/2.8). In an upper-body portrait at 1.42 m, the sharp depth-of-field zone spans 29 cm (1.29 m to 1.58 m) with a 54° horizontal background angle of view.
Does the Canon 35mm f/2 IS show focus breathing at portrait distance?
Based on patent US20150205081A1, tracing the focusing group at 1.42 m gives an effective framing focal length of 35.0 mm (-0.0% vs. the nominal 35 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Canon 35mm f/2 IS?
The patent prescription (US20150205081A1) specifies 10 lens elements in 8 groups with 1 aspherical surfaces. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Canon 35mm f/2.8 Macro
- Canon 40mm f/2.8 STM
- Canon 28mm f/1.8 USM
- 24mm vs 35mm focal length comparison
- 28mm vs 35mm focal length comparison
- 35mm vs 40mm focal length comparison
Compare with similar portrait lenses
- Canon EF 35mm f/2
- Sony AF 35mm F2
- Sony Hexar 35mm F2
- Nikon 35mm f/2 AF-D FX
- Nikon 35mm f/2 AI-s
- Sony FE 50mm F2.8 Macro
Also see: depth of field, bokeh, crop factor, lens compression.