Nikon AF 28mm f/1.4D — Bokeh & Optical Ray-Tracing Simulator

Interactive 3D portrait ray-traced through the published US5315441A optical prescription (11 elements in 8 groups, 1 aspherical) with a 20.0 mm entrance pupil and 0.35 m minimum focus.

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Optical & Portrait Specifications (Upper Body Framing)

Optical & Portrait Metric Measured / Patent Value What It Means in Practice
Patent Prescription US5315441A · 11 elements in 8 groups (1 aspherical) Traced surface by surface in WebGL2
Entrance Pupil Diameter 20.0 mm (at f/1.4) Controls distant background blur disc size
Corner Bokeh Roundness (90% Field) 53% at f/1.4 (≥86% from f/2.8) · -1.4 EV Mechanical vignetting (cat’s-eye vs. round corner highlights)
Background Field of View (Compression) 66° horizontal Width of the background room visible behind the subject
Upper-Body Working Distance 1.15 m Camera-to-subject distance for head-to-waist framing
Effective Focal Length (Breathing) 27.8 mm (-0.5%) Actual framing focal length at portrait distance
Depth of Field (Sharp Zone) 21 cm (1.05 m – 1.26 m) Sharp zone at wide-open aperture
Minimum Focus Distance 0.35 m Closest focusing distance from the sensor

Questions

How much background blur and corner cat's-eye does the Nikon AF 28mm f/1.4D produce?

Wide open at f/1.4, the Nikon AF 28mm f/1.4D has a 20.0 mm entrance pupil (28 mm ÷ 1.4) and 53% bokeh roundness in the 90% corner (-1.4 EV corner falloff, reaching ≥86% roundness from f/2.8). In an upper-body portrait at 1.15 m, the sharp depth-of-field zone spans 21 cm (1.05 m to 1.26 m) with a 66° horizontal background angle of view.

Does the Nikon AF 28mm f/1.4D show focus breathing at portrait distance?

Based on patent US5315441A, tracing the focusing group at 1.15 m gives an effective framing focal length of 27.8 mm (-0.5% vs. the nominal 28 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.

What optical design is inside the Nikon AF 28mm f/1.4D?

The patent prescription (US5315441A) specifies 11 lens elements in 8 groups with 1 aspherical surfaces. The interactive Optical X-Ray above traces rays through every surface in real time.

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Also see: depth of field, bokeh, crop factor, lens compression.