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Sigma 50mm F1.2 DG DN | Art — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published JP 2025-124346 A optical prescription (17 elements in 12 groups, 6 aspherical) with a 41.7 mm entrance pupil and 0.4 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | JP 2025-124346 A · 17 elements in 12 groups (6 aspherical) | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 41.7 mm (at f/1.2) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 59% at f/1.2 (≥86% from f/2.8) · -1.2 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 40° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 2.01 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 49.4 mm (-1.2%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 17 cm (1.93 m – 2.10 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.4 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Sigma 50mm F1.2 DG DN | Art produce?
Wide open at f/1.2, the Sigma 50mm F1.2 DG DN | Art has a 41.7 mm entrance pupil (50 mm ÷ 1.2) and 59% bokeh roundness in the 90% corner (-1.2 EV corner falloff, reaching ≥86% roundness from f/2.8). In an upper-body portrait at 2.01 m, the sharp depth-of-field zone spans 17 cm (1.93 m to 2.10 m) with a 40° horizontal background angle of view.
Does the Sigma 50mm F1.2 DG DN | Art show focus breathing at portrait distance?
Based on patent JP 2025-124346 A, tracing the focusing group at 2.01 m gives an effective framing focal length of 49.4 mm (-1.2% vs. the nominal 50 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Sigma 50mm F1.2 DG DN | Art?
The patent prescription (JP 2025-124346 A) specifies 17 lens elements in 12 groups with 6 aspherical surfaces. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Sigma 50mm F1.4 DG DN | Art
- Sigma 56mm F1.4 DC DN | Contemporary
- 24mm vs 50mm focal length comparison
- 28mm vs 50mm focal length comparison
- 35mm vs 50mm focal length comparison
- 40mm vs 50mm focal length comparison
Compare with similar portrait lenses
- Sony FE 50mm F1.2 GM
- Nikon NIKKOR Z 50mm f/1.2 S
- Canon RF 50mm F1.2 L USM
- Leica NOCTILUX 50mm f/1.2 ASPH
- Sony FE 50mm F1.4 GM
- Canon RF 85mm F2 MACRO IS STM
Also see: depth of field, bokeh, crop factor, lens compression.