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Nikon NIKKOR Z 20mm f/1.8 S — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published WO2021117429A1 optical prescription (15 elements in 11 groups, 5 aspherical) with a 11.1 mm entrance pupil and 0.2 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | WO2021117429A1 · 15 elements in 11 groups (5 aspherical) | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 11.1 mm (at f/1.8) | Controls distant background blur disc size |
| Upper-Body Working Distance | 0.84 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 19.7 mm (-1.3%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 28 cm (72 cm – 100 cm) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.2 m | Closest focusing distance from the sensor |
Questions
How much background blur does the Nikon NIKKOR Z 20mm f/1.8 S produce?
Wide open at f/1.8, the Nikon NIKKOR Z 20mm f/1.8 S has a 11.1 mm entrance pupil (20 mm ÷ 1.8). In an upper-body portrait at 0.84 m, the sharp depth-of-field zone spans 28 cm (72 cm to 100 cm), while mechanical vignetting and 15 glass elements shape the out-of-focus highlights.
Does the Nikon NIKKOR Z 20mm f/1.8 S show focus breathing at portrait distance?
Based on patent WO2021117429A1, tracing the focusing group at 0.84 m gives an effective framing focal length of 19.7 mm (-1.3% vs. the nominal 20 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Nikon NIKKOR Z 20mm f/1.8 S?
The patent prescription (WO2021117429A1) specifies 15 lens elements in 11 groups with 5 aspherical surfaces. The interactive Optical X-Ray above traces rays through every surface in real time.
Head-to-head patent comparisons with Nikon NIKKOR Z 20mm f/1.8 S
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Also see: depth of field, bokeh, crop factor, lens compression.