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Sigma 105mm F1.4 DG HSM | Art — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published JP2019144477A optical prescription (17 elements in 12 groups, 2 aspherical) with a 75.0 mm entrance pupil and 1 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | JP2019144477A · 17 elements in 12 groups (2 aspherical) | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 75.0 mm (at f/1.4) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 81% at f/1.4 (≥86% from f/1.8) · -0.3 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 19° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 4.21 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 108.6 mm (+3.4%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 20 cm (4.11 m – 4.31 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 1 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Sigma 105mm F1.4 DG HSM | Art produce?
Wide open at f/1.4, the Sigma 105mm F1.4 DG HSM | Art has a 75.0 mm entrance pupil (105 mm ÷ 1.4) and 81% bokeh roundness in the 90% corner (-0.3 EV corner falloff, reaching ≥86% roundness from f/1.8). In an upper-body portrait at 4.21 m, the sharp depth-of-field zone spans 20 cm (4.11 m to 4.31 m) with a 19° horizontal background angle of view.
Does the Sigma 105mm F1.4 DG HSM | Art show focus breathing at portrait distance?
Based on patent JP2019144477A, tracing the focusing group at 4.21 m gives an effective framing focal length of 108.6 mm (+3.4% vs. the nominal 105 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Sigma 105mm F1.4 DG HSM | Art?
The patent prescription (JP2019144477A) specifies 17 lens elements in 12 groups with 2 aspherical surfaces. The interactive Optical X-Ray above traces rays through every surface in real time.
Head-to-head patent comparisons with Sigma 105mm F1.4 DG HSM | Art
Related comparisons
- Nikon 105mm f/1.4 FX
- Nikon NIKKOR Z MC 105mm f/2.8 VR S
- Sony FE 135mm F1.8 GM
- Nikon NIKKOR Z 135mm f/1.8 S Plena
- Canon RF 135mm F1.8 L IS USM
Also see: depth of field, bokeh, crop factor, lens compression.