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Nikon 16mm f/2.8 AI-s Fisheye — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published US5434713A optical prescription (8 elements in 5 groups) with a 5.7 mm entrance pupil and 0.25 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | US5434713A · 8 elements in 5 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 5.7 mm (at f/2.8) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 35% at f/2.8 · -4.1 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 122° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 0.68 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 10.0 mm (-37.5%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 50 cm (51 cm – 1.01 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.25 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Nikon 16mm f/2.8 AI-s Fisheye produce?
Wide open at f/2.8, the Nikon 16mm f/2.8 AI-s Fisheye has a 5.7 mm entrance pupil (16 mm ÷ 2.8) and 35% bokeh roundness in the 90% corner (-4.1 EV corner falloff). In an upper-body portrait at 0.68 m, the sharp depth-of-field zone spans 50 cm (51 cm to 1.01 m) with a 122° horizontal background angle of view.
Does the Nikon 16mm f/2.8 AI-s Fisheye show focus breathing at portrait distance?
Based on patent US5434713A, tracing the focusing group at 0.68 m gives an effective framing focal length of 10.0 mm (-37.5% vs. the nominal 16 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Nikon 16mm f/2.8 AI-s Fisheye?
The patent prescription (US5434713A) specifies 8 lens elements in 5 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Nikon 15mm f/5.6
- Nikon 18mm f/2.8D FX
- Nikon 18mm f/4 AI-s
- Nikon 19mm f/4 PC-E FX
- Nikon 13mm f/5.6 FX
- Nikon AF-S 20mm f/1.8G ED
Compare with similar portrait lenses
- Canon RF 16mm F2.8 STM
- Canon 15mm f/2.8 Fisheye
- Sony Batis 18mm F2.8
- Fujifilm XF 16mm F2.8 R WR
- Nikon Nikkor-O 2.1cm f/4
Also see: depth of field, bokeh, crop factor, lens compression.