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Leica SUMMARON 35mm f/2.8 — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published FR1471493A optical prescription (7 elements in 5 groups) with a 12.5 mm entrance pupil and 0.7 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | FR1471493A · 7 elements in 5 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 12.5 mm (at f/2.8) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 69% at f/2.8 (≥86% from f/4) · -0.7 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) | 35.3 mm (+0.9%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 41 cm (1.24 m – 1.66 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.7 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Leica SUMMARON 35mm f/2.8 produce?
Wide open at f/2.8, the Leica SUMMARON 35mm f/2.8 has a 12.5 mm entrance pupil (35 mm ÷ 2.8) and 69% bokeh roundness in the 90% corner (-0.7 EV corner falloff, reaching ≥86% roundness from f/4). In an upper-body portrait at 1.42 m, the sharp depth-of-field zone spans 41 cm (1.24 m to 1.66 m) with a 54° horizontal background angle of view.
Does the Leica SUMMARON 35mm f/2.8 show focus breathing at portrait distance?
Based on patent FR1471493A, tracing the focusing group at 1.42 m gives an effective framing focal length of 35.3 mm (+0.9% 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 Leica SUMMARON 35mm f/2.8?
The patent prescription (FR1471493A) specifies 7 lens elements in 5 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Leica Summicron-C 40mm f/2
- 24mm vs 35mm focal length comparison
- 28mm vs 35mm focal length comparison
- 35mm vs 40mm focal length comparison
- 35mm vs 50mm focal length comparison
- 35mm vs 58mm focal length comparison
Compare with similar portrait lenses
- Sony Sonnar FE 35mm F2.8 ZA
- Nikon 35mm f/2.8 PC
- Canon 35mm f/2.8 Macro
- Sony AF 35mm F2
- Sony Hexar 35mm F2
- Nikon 24mm f/2.0 AI-s
Also see: depth of field, bokeh, crop factor, lens compression.