Interactive 3D portrait ray-traced through the published GOI OPAL construction ST01FB06 optical prescription (6 elements in 4 groups) with a 29.0 mm entrance pupil and 0.5 m minimum focus.
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| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | GOI OPAL construction ST01FB06 · 6 elements in 4 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 29.0 mm (at f/2) | Controls distant background blur disc size |
| Upper-Body Working Distance | 2.33 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 59.4 mm (+2.5%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 28 cm (2.20 m – 2.48 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.5 m | Closest focusing distance from the sensor |
Wide open at f/2, the Helios 44-2 58mm f/2 has a 29.0 mm entrance pupil (58 mm ÷ 2). In an upper-body portrait at 2.33 m, the sharp depth-of-field zone spans 28 cm (2.20 m to 2.48 m), while mechanical vignetting and 6 glass elements shape the out-of-focus highlights.
Based on patent GOI OPAL construction ST01FB06, tracing the focusing group at 2.33 m gives an effective framing focal length of 59.4 mm (+2.5% vs. the nominal 58 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
The patent prescription (GOI OPAL construction ST01FB06) specifies 6 lens elements in 4 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
Voir aussi: profondeur de champ, bokeh, facteur de recadrage, compression.
