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Sigma 85mm F1.4 DG DN | Art — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published JP 2021-085935 A optical prescription (15 elements in 11 groups, 2 aspherical) with a 60.7 mm entrance pupil and 0.85 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | JP 2021-085935 A · 15 elements in 11 groups (2 aspherical) | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 60.7 mm (at f/1.4) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 69% at f/1.4 (≥86% from f/4) · -0.7 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 23° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 3.41 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 89.2 mm (+5.0%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 20 cm (3.31 m – 3.51 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.85 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Sigma 85mm F1.4 DG DN | Art produce?
Wide open at f/1.4, the Sigma 85mm F1.4 DG DN | Art has a 60.7 mm entrance pupil (85 mm ÷ 1.4) and 69% bokeh roundness in the 90% corner (-0.7 EV corner falloff, reaching ≥86% roundness from f/4). In an upper-body portrait at 3.41 m, the sharp depth-of-field zone spans 20 cm (3.31 m to 3.51 m) with a 23° horizontal background angle of view.
Does the Sigma 85mm F1.4 DG DN | Art show focus breathing at portrait distance?
Based on patent JP 2021-085935 A, tracing the focusing group at 3.41 m gives an effective framing focal length of 89.2 mm (+5.0% vs. the nominal 85 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Sigma 85mm F1.4 DG DN | Art?
The patent prescription (JP 2021-085935 A) specifies 15 lens elements in 11 groups with 2 aspherical surfaces. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Sigma 85mm F1.2 DG | Art
- Sigma 85mm F1.4 DG HSM | Art
- Sigma 105mm F1.4 DG HSM | Art
- 35mm vs 85mm focal length comparison
- 40mm vs 85mm focal length comparison
- 50mm vs 85mm focal length comparison
Compare with similar portrait lenses
- Sony FE 85mm F1.4 GM II
- Sony FE 85mm F1.4 GM
- Nikon 85mm f/1.4 G FX
- Nikon 85mm f/1.4 AI-s
- Nikon AF 85mm f/1.4D IF
- Nikon 105mm f/1.8 AI-s
Also see: depth of field, bokeh, crop factor, lens compression.