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Leica Summicron-M 66mm f/2 — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published US3552833A optical prescription (6 elements in 5 groups) with a 33.0 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 | US3552833A · 6 elements in 5 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 33.0 mm (at f/2) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 100% at f/2 · -0.1 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 30° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 2.65 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 67.3 mm (+2.0%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 28 cm (2.52 m – 2.80 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 Summicron-M 66mm f/2 produce?
Wide open at f/2, the Leica Summicron-M 66mm f/2 has a 33.0 mm entrance pupil (66 mm ÷ 2) and 100% bokeh roundness in the 90% corner (-0.1 EV corner falloff). In an upper-body portrait at 2.65 m, the sharp depth-of-field zone spans 28 cm (2.52 m to 2.80 m) with a 30° horizontal background angle of view.
Does the Leica Summicron-M 66mm f/2 show focus breathing at portrait distance?
Based on patent US3552833A, tracing the focusing group at 2.65 m gives an effective framing focal length of 67.3 mm (+2.0% vs. the nominal 66 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Leica Summicron-M 66mm f/2?
The patent prescription (US3552833A) specifies 6 lens elements in 5 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Leica Noctilux-M 50mm f/0.95 ASPH.
- Leica Summilux-M 50mm f/1.4
- Leica APO-Summicron-M 50mm f/2 ASPH.
- Leica Summicron-M 50mm f/2
- Leica ELMAR-M 50mm f/2.8
Compare with similar portrait lenses
- Nikon 60mm f/2.8 G Macro FX
- Nikon 58mm f/1.4 G FX
- Nikon Nikkor-S Auto 58mm f/1.4
- Nikon 58mm f/1.2 Noct-NIKKOR
- Fujifilm GF 63mm F2.8 R WR
- Sony FE 90mm F2.8 Macro G OSS
Also see: depth of field, bokeh, crop factor, lens compression.