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Sony FE 20mm F1.8 G — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published WO2020213337A1 optical prescription (14 elements in 12 groups, 4 aspherical) with a 11.1 mm entrance pupil and 0.19 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | WO2020213337A1 · 14 elements in 12 groups (4 aspherical) | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 11.1 mm (at f/1.8) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 85% at f/1.8 (≥86% from f/2) · -0.9 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 84° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 0.84 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 19.8 mm (-0.8%) | 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 | 0.19 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Sony FE 20mm F1.8 G produce?
Wide open at f/1.8, the Sony FE 20mm F1.8 G has a 11.1 mm entrance pupil (20 mm ÷ 1.8) and 85% bokeh roundness in the 90% corner (-0.9 EV corner falloff, reaching ≥86% roundness from f/2). In an upper-body portrait at 0.84 m, the sharp depth-of-field zone spans 28 cm (72 cm to 100 cm) with a 84° horizontal background angle of view.
Does the Sony FE 20mm F1.8 G show focus breathing at portrait distance?
Based on patent WO2020213337A1, tracing the focusing group at 0.84 m gives an effective framing focal length of 19.8 mm (-0.8% 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 Sony FE 20mm F1.8 G?
The patent prescription (WO2020213337A1) specifies 14 lens elements in 12 groups with 4 aspherical surfaces. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Sony FE 20mm F1.8 G vs. Sony FE 24mm F1.4 GM
- Sony FE 20mm F1.8 G vs. Sony FE 14mm F1.8 GM
- Sony FE 24mm F1.4 GM
- Sony FE 24mm F2.8 G
Compare with similar portrait lenses
- Nikon NIKKOR Z 20mm f/1.8 S
- Nikon AF-S 20mm f/1.8G ED
- Canon RF 20mm F1.4 L VCM
- Nikon 20mm f/2.8 AI-s
- Canon 20mm f/2.8 USM
- Nikon 24mm f/2.0 AI-s
Also see: depth of field, bokeh, crop factor, lens compression.