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Nikon 6mm f/2.8 Fisheye-Nikkor — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published US3737214A optical prescription (13 elements in 10 groups) with a 2.1 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 | US3737214A · 13 elements in 10 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 2.1 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) | 143° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 0.31 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 6.0 mm (-0.0%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | infinity (15 cm – infinity) | 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 6mm f/2.8 Fisheye-Nikkor produce?
Wide open at f/2.8, the Nikon 6mm f/2.8 Fisheye-Nikkor has a 2.1 mm entrance pupil (6 mm ÷ 2.8) and 35% bokeh roundness in the 90% corner (-4.1 EV corner falloff). In an upper-body portrait at 0.31 m, the sharp depth-of-field zone spans infinity (15 cm to infinity) with a 143° horizontal background angle of view.
Does the Nikon 6mm f/2.8 Fisheye-Nikkor show focus breathing at portrait distance?
Based on patent US3737214A, tracing the focusing group at 0.31 m gives an effective framing focal length of 6.0 mm (-0.0% vs. the nominal 6 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Nikon 6mm f/2.8 Fisheye-Nikkor?
The patent prescription (US3737214A) specifies 13 lens elements in 10 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
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Compare with similar portrait lenses
- Canon RF 5.2mm F2.8 L DUAL FISHEYE
- Canon RF-S 3.9mm F3.5 STM DUAL FISHEYE
- Canon RF-S 7.8mm F4 STM DUAL LENS
- Fujifilm XF 8mm F3.5 R WR
Also see: depth of field, bokeh, crop factor, lens compression.