Find a lens for this look
eBay links may earn us a commission, at no extra cost to you.
Matching lenses from each maker's lineup, plus some classic medium and large format lenses. Email me if something is wrong or missing.
Nikon 45mm f/2.8P AI-P — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published JP2003-005030A optical prescription (4 elements in 3 groups) with a 16.1 mm entrance pupil and 0.45 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | JP2003-005030A · 4 elements in 3 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 16.1 mm (at f/2.8) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 94% at f/2.8 · -0.2 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 43° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 1.82 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 45.8 mm (+1.7%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 40 cm (1.64 m – 2.04 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.45 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Nikon 45mm f/2.8P AI-P produce?
Wide open at f/2.8, the Nikon 45mm f/2.8P AI-P has a 16.1 mm entrance pupil (45 mm ÷ 2.8) and 94% bokeh roundness in the 90% corner (-0.2 EV corner falloff). In an upper-body portrait at 1.82 m, the sharp depth-of-field zone spans 40 cm (1.64 m to 2.04 m) with a 43° horizontal background angle of view.
Does the Nikon 45mm f/2.8P AI-P show focus breathing at portrait distance?
Based on patent JP2003-005030A, tracing the focusing group at 1.82 m gives an effective framing focal length of 45.8 mm (+1.7% vs. the nominal 45 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Nikon 45mm f/2.8P AI-P?
The patent prescription (JP2003-005030A) specifies 4 lens elements in 3 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- Nikon 45mm f/2.8 PC-E
- Nikon 50mm f/1.4 AI-s
- Nikon AF-S 50mm f/1.4G
- Nikon Nikkor-S Auto 50mm f/1.4
- Nikon 50mm f/1.8 AI-s
- Nikon 50mm f/2
Compare with similar portrait lenses
- Sony FE 50mm F2.8 Macro
- Sony AF 50mm F2.8 Macro
- Canon 40mm f/2.8 STM
- Leica DG Macro-Elmarit 45mm f/2.8 ASPH.
- Nikon 35mm f/2 AF-D FX
Also see: depth of field, bokeh, crop factor, lens compression.