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Leica SUPER-ELMAR-M 18mm f/3.8 ASPH — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published US20200341238A1 optical prescription (10 elements in 6 groups, 4 aspherical) with a 4.7 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 | US20200341238A1 · 10 elements in 6 groups (4 aspherical) | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 4.7 mm (at f/3.8) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 81% at f/3.8 (≥86% from f/5.6) · -1.0 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 90° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 0.76 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 18.0 mm (-0.0%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 69 cm (55 cm – 1.24 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 SUPER-ELMAR-M 18mm f/3.8 ASPH produce?
Wide open at f/3.8, the Leica SUPER-ELMAR-M 18mm f/3.8 ASPH has a 4.7 mm entrance pupil (18 mm ÷ 3.8) and 81% bokeh roundness in the 90% corner (-1.0 EV corner falloff, reaching ≥86% roundness from f/5.6). In an upper-body portrait at 0.76 m, the sharp depth-of-field zone spans 69 cm (55 cm to 1.24 m) with a 90° horizontal background angle of view.
Does the Leica SUPER-ELMAR-M 18mm f/3.8 ASPH show focus breathing at portrait distance?
Based on patent US20200341238A1, tracing the focusing group at 0.76 m gives an effective framing focal length of 18.0 mm (-0.0% vs. the nominal 18 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Leica SUPER-ELMAR-M 18mm f/3.8 ASPH?
The patent prescription (US20200341238A1) specifies 10 lens elements in 6 groups with 4 aspherical surfaces. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Leica Super-Elmar-M 21mm f/3.4 ASPH.
- 24mm vs 35mm focal length comparison
- 24mm vs 50mm focal length comparison
- 28mm vs 35mm focal length comparison
- 28mm vs 50mm focal length comparison
- 23mm APS-C vs 35mm full frame focal length comparison
Compare with similar portrait lenses
- Nikon 18mm f/4 AI-s
- Nikon 19mm f/4 PC-E FX
- Sony Batis 18mm F2.8
- Canon FD 17mm f/4
- Nikon 18mm f/2.8D FX
- Canon 14mm f/2.8 L II
Also see: depth of field, bokeh, crop factor, lens compression.