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Matching lenses from each maker's lineup, plus some classic medium and large format lenses. Email me if something is wrong or missing.
Interactive 3D portrait ray-traced through the published US3576360A optical prescription (9 elements in 7 groups) with a 25.0 mm entrance pupil and 0.3 m minimum focus.
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Matching lenses from each maker's lineup, plus some classic medium and large format lenses. Email me if something is wrong or missing.
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | US3576360A · 9 elements in 7 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 25.0 mm (at f/1.4) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 57% at f/1.4 (≥86% from f/2.8) · -1.3 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 55° 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) | 34.7 mm (-1.0%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 20 cm (1.33 m – 1.53 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.3 m | Closest focusing distance from the sensor |
Wide open at f/1.4, the Nikon 35mm f/1.4 AI-s has a 25.0 mm entrance pupil (35 mm ÷ 1.4) and 57% bokeh roundness in the 90% corner (-1.3 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 20 cm (1.33 m to 1.53 m) with a 55° horizontal background angle of view.
Based on patent US3576360A, tracing the focusing group at 1.42 m gives an effective framing focal length of 34.7 mm (-1.0% vs. the nominal 35 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
The patent prescription (US3576360A) specifies 9 lens elements in 7 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
Also see: depth of field, bokeh, crop factor, lens compression.