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Helios 44-2 58mm f/2 — Bokeh & Optical Ray-Tracing Simulator
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.
Optical & Portrait Specifications (Upper Body Framing)
| 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 |
| Corner Bokeh Roundness (90% Field) | 61% at f/2 (≥86% from f/4) · -1.3 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 34° horizontal | Width of the background room visible behind the subject |
| 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 |
Questions
How much background blur and corner cat's-eye does the Helios 44-2 58mm f/2 produce?
Wide open at f/2, the Helios 44-2 58mm f/2 has a 29.0 mm entrance pupil (58 mm ÷ 2) and 61% bokeh roundness in the 90% corner (-1.3 EV corner falloff, reaching ≥86% roundness from f/4). 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) with a 34° horizontal background angle of view.
Does the Helios 44-2 58mm f/2 show focus breathing at portrait distance?
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.
What optical design is inside the Helios 44-2 58mm f/2?
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.
Related comparisons
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Compare with similar portrait lenses
- Sony Sonnar FE 55mm F1.8 ZA
- Nikon 58mm f/1.4 G FX
- Nikon Nikkor-S Auto 58mm f/1.4
- Nikon 60mm f/2.8 G Macro FX
- Sony MD 50mm F2
- Nikon NIKKOR Z 35mm f/1.2 S
Also see: depth of field, bokeh, crop factor, lens compression.