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Nikon 40mm f/2.8 Macro DX — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published US20110176215A1 optical prescription (9 elements in 7 groups) with a 14.3 mm entrance pupil and 0.16 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | US20110176215A1 · 9 elements in 7 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 14.3 mm (at f/2.8) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 97% at f/2.8 · -0.1 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 33° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 2.45 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 40.3 mm (+0.8%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 62 cm (2.18 m – 2.80 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.16 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Nikon 40mm f/2.8 Macro DX produce?
Wide open at f/2.8, the Nikon 40mm f/2.8 Macro DX has a 14.3 mm entrance pupil (40 mm ÷ 2.8) and 97% bokeh roundness in the 90% corner (-0.1 EV corner falloff). In an upper-body portrait at 2.45 m, the sharp depth-of-field zone spans 62 cm (2.18 m to 2.80 m) with a 33° horizontal background angle of view.
Does the Nikon 40mm f/2.8 Macro DX show focus breathing at portrait distance?
Based on patent US20110176215A1, tracing the focusing group at 2.45 m gives an effective framing focal length of 40.3 mm (+0.8% 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 40mm f/2.8 Macro DX?
The patent prescription (US20110176215A1) specifies 9 lens elements in 7 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Nikon 35mm f/1.4 AI-s
- Nikon 35mm f/1.8 DX
- Nikon 35mm f/2 AF-D FX
- Nikon 35mm f/2 AI-s
- Nikon 35mm f/2.8 PC
- Nikon 45mm f/2.8 PC-E
Compare with similar portrait lenses
Also see: depth of field, bokeh, crop factor, lens compression.