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Sigma 56mm F1.4 DC DN | Contemporary — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published JP2020030383A optical prescription (10 elements in 6 groups, 3 aspherical) with a 40.0 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 | JP2020030383A · 10 elements in 6 groups (3 aspherical) | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 40.0 mm (at f/1.4) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 79% at f/1.4 (≥86% from f/1.8) · -0.4 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 | 3.42 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 57.8 mm (+3.2%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 30 cm (3.28 m – 3.58 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 Sigma 56mm F1.4 DC DN | Contemporary produce?
Wide open at f/1.4, the Sigma 56mm F1.4 DC DN | Contemporary has a 40.0 mm entrance pupil (56 mm ÷ 1.4) and 79% bokeh roundness in the 90% corner (-0.4 EV corner falloff, reaching ≥86% roundness from f/1.8). In an upper-body portrait at 3.42 m, the sharp depth-of-field zone spans 30 cm (3.28 m to 3.58 m) with a 23° horizontal background angle of view.
Does the Sigma 56mm F1.4 DC DN | Contemporary show focus breathing at portrait distance?
Based on patent JP2020030383A, tracing the focusing group at 3.42 m gives an effective framing focal length of 57.8 mm (+3.2% vs. the nominal 56 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Sigma 56mm F1.4 DC DN | Contemporary?
The patent prescription (JP2020030383A) specifies 10 lens elements in 6 groups with 3 aspherical surfaces. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Sigma 50mm F1.2 DG DN | Art
- Sigma 50mm F1.4 DG DN | Art
- 56mm APS-C vs 85mm full frame focal length comparison
- 35mm vs 58mm focal length comparison
- 50mm vs 58mm focal length comparison
- 58mm vs 85mm focal length comparison
Compare with similar portrait lenses
- Fujifilm XF 56mm F1.2 R WR
- Fujifilm XF 56mm F1.2 R APD
- Fujifilm XF 56mm F1.2 R
- Nikon 58mm f/1.4 G FX
- Nikon Nikkor-S Auto 58mm f/1.4
- Canon RF 45mm F1.2 STM
Also see: depth of field, bokeh, crop factor, lens compression.