Interactive 3D portrait ray-traced through the published JP2013-054269A optical prescription (9 elements in 7 groups, 1 aspherical) with a 10.0 mm entrance pupil and 0.23 m minimum focus.
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| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | JP2013-054269A · 9 elements in 7 groups (1 aspherical) | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 10.0 mm (at f/2.8) | Controls distant background blur disc size |
| Upper-Body Working Distance | 1.15 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 27.8 mm (-0.7%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 42 cm (97 cm – 1.40 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.23 m | Closest focusing distance from the sensor |
Wide open at f/2.8, the Canon RF 28mm F2.8 STM has a 10.0 mm entrance pupil (28 mm ÷ 2.8). In an upper-body portrait at 1.15 m, the sharp depth-of-field zone spans 42 cm (97 cm to 1.40 m), while mechanical vignetting and 9 glass elements shape the out-of-focus highlights.
Based on patent JP2013-054269A, tracing the focusing group at 1.15 m gives an effective framing focal length of 27.8 mm (-0.7% vs. the nominal 28 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
The patent prescription (JP2013-054269A) specifies 9 lens elements in 7 groups with 1 aspherical surfaces. The interactive Optical X-Ray above traces rays through every surface in real time.
Voir aussi: profondeur de champ, bokeh, facteur de recadrage, compression.
