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Nikon NIKKOR Z 40mm f/2 — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published JP2021-189351A optical prescription (8 elements in 4 groups, 2 aspherical) with a 20.0 mm entrance pupil and 0.29 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | JP2021-189351A · 8 elements in 4 groups (2 aspherical) | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 20.0 mm (at f/2) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 86% at f/2 · -0.6 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 50° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 1.62 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 39.0 mm (-2.4%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 29 cm (1.49 m – 1.78 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.29 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Nikon NIKKOR Z 40mm f/2 produce?
Wide open at f/2, the Nikon NIKKOR Z 40mm f/2 has a 20.0 mm entrance pupil (40 mm ÷ 2) and 86% bokeh roundness in the 90% corner (-0.6 EV corner falloff). In an upper-body portrait at 1.62 m, the sharp depth-of-field zone spans 29 cm (1.49 m to 1.78 m) with a 50° horizontal background angle of view.
Does the Nikon NIKKOR Z 40mm f/2 show focus breathing at portrait distance?
Based on patent JP2021-189351A, tracing the focusing group at 1.62 m gives an effective framing focal length of 39.0 mm (-2.4% vs. the nominal 40 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Nikon NIKKOR Z 40mm f/2?
The patent prescription (JP2021-189351A) specifies 8 lens elements in 4 groups with 2 aspherical surfaces. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Nikon NIKKOR Z 40mm f/2 vs. Nikon NIKKOR Z 50mm f/1.8 S
- Nikon NIKKOR Z 40mm f/2 vs. Nikon NIKKOR Z 28mm f/2.8
- Nikon NIKKOR Z 35mm f/1.2 S
- Nikon NIKKOR Z 35mm f/1.4
- Nikon NIKKOR Z 35mm f/1.8 S
- Nikon NIKKOR Z 50mm f/1.2 S
Compare with similar portrait lenses
- Sony Hexanon AR 40mm F1.8
- Leica Summicron-C 40mm f/2
- Nikon 35mm f/2 AF-D FX
- Nikon 35mm f/2 AI-s
- Canon 40mm f/2.8 STM
- Nikon 28mm f/1.4E FX
Also see: depth of field, bokeh, crop factor, lens compression.