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Zeiss Biotar 75mm f/1.5 — Simulatore di bokeh e ray-tracing ottico
Interactive 3D portrait ray-traced through the published DE485798C optical prescription (6 elements in 4 groups) with a 50.0 mm entrance pupil and 1 m minimum focus.
Specifiche ottiche e ritratto (inquadratura mezzo busto)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | DE485798C · 6 elements in 4 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 50.0 mm (at f/1.5) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 96% at f/1.5 · -0.1 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 27° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 3.01 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 75.2 mm (+0.3%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 21 cm (2.91 m – 3.12 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 1 m | Closest focusing distance from the sensor |
Domande
How much background blur and corner cat's-eye does the Zeiss Biotar 75mm f/1.5 produce?
Wide open at f/1.5, the Zeiss Biotar 75mm f/1.5 has a 50.0 mm entrance pupil (75 mm ÷ 1.5) and 96% bokeh roundness in the 90% corner (-0.1 EV corner falloff). In an upper-body portrait at 3.01 m, the sharp depth-of-field zone spans 21 cm (2.91 m to 3.12 m) with a 27° horizontal background angle of view.
Does the Zeiss Biotar 75mm f/1.5 show focus breathing at portrait distance?
Based on patent DE485798C, tracing the focusing group at 3.01 m gives an effective framing focal length of 75.2 mm (+0.3% vs. the nominal 75 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Zeiss Biotar 75mm f/1.5?
The patent prescription (DE485798C) specifies 6 lens elements in 4 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
Confronti diretti da brevetto con Zeiss Biotar 75mm f/1.5
Confronti collegati
- Sony FE 85mm F1.4 GM II
- Sony FE 85mm F1.4 GM
- Nikon 85mm f/1.4 G FX
- Nikon 58mm f/1.2 Noct-NIKKOR
- Canon 50mm f/1.0 L
Vedi anche: profondità di campo, bokeh, fattore di crop, compressione.