Nikon NIKKOR Z 400mm f/2.8 TC VR S — Bokeh & Optical Ray-Tracing Simulator

Interactive 3D portrait ray-traced through the published WO2021256065A1 optical prescription (18 elements in 15 groups) with a 142.9 mm entrance pupil and 2.5 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 WO2021256065A1 · 18 elements in 15 groups Traced surface by surface in WebGL2
Entrance Pupil Diameter 142.9 mm (at f/2.8) Controls distant background blur disc size
Corner Bokeh Roundness (90% Field) 55% at f/2.8 (≥86% from f/5.6) · -1.0 EV Mechanical vignetting (cat’s-eye vs. round corner highlights)
Background Field of View (Compression) 5° horizontal Width of the background room visible behind the subject
Upper-Body Working Distance 15.99 m Camera-to-subject distance for head-to-waist framing
Effective Focal Length (Breathing) 385.8 mm (-3.5%) Actual framing focal length at portrait distance
Depth of Field (Sharp Zone) 39 cm (16 m – 16 m) Sharp zone at wide-open aperture
Minimum Focus Distance 2.5 m Closest focusing distance from the sensor

Questions

How much background blur and corner cat's-eye does the Nikon NIKKOR Z 400mm f/2.8 TC VR S produce?

Wide open at f/2.8, the Nikon NIKKOR Z 400mm f/2.8 TC VR S has a 142.9 mm entrance pupil (400 mm ÷ 2.8) and 55% bokeh roundness in the 90% corner (-1.0 EV corner falloff, reaching ≥86% roundness from f/5.6). In an upper-body portrait at 15.99 m, the sharp depth-of-field zone spans 39 cm (16 m to 16 m) with a 5° horizontal background angle of view.

Does the Nikon NIKKOR Z 400mm f/2.8 TC VR S show focus breathing at portrait distance?

Based on patent WO2021256065A1, tracing the focusing group at 15.99 m gives an effective framing focal length of 385.8 mm (-3.5% vs. the nominal 400 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 400mm f/2.8 TC VR S?

The patent prescription (WO2021256065A1) specifies 18 lens elements in 15 groups. 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.