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Nikon 15mm f/5.6 — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published JP S48-071634A optical prescription (15 elements in 13 groups) with a 2.7 mm entrance pupil and 0.3 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | JP S48-071634A · 15 elements in 13 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 2.7 mm (at f/5.6) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 35% at f/5.6 · -4.1 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 102° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 0.64 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 14.7 mm (-2.3%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 171 cm (38 cm – 2.09 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.3 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Nikon 15mm f/5.6 produce?
Wide open at f/5.6, the Nikon 15mm f/5.6 has a 2.7 mm entrance pupil (15 mm ÷ 5.6) and 35% bokeh roundness in the 90% corner (-4.1 EV corner falloff). In an upper-body portrait at 0.64 m, the sharp depth-of-field zone spans 171 cm (38 cm to 2.09 m) with a 102° horizontal background angle of view.
Does the Nikon 15mm f/5.6 show focus breathing at portrait distance?
Based on patent JP S48-071634A, tracing the focusing group at 0.64 m gives an effective framing focal length of 14.7 mm (-2.3% vs. the nominal 15 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Nikon 15mm f/5.6?
The patent prescription (JP S48-071634A) specifies 15 lens elements in 13 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
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Also see: depth of field, bokeh, crop factor, lens compression.