Leica TELE-ELMARIT-M 90mm f/2.8 — Bokeh & Optical Ray-Tracing Simulator

Interactive 3D portrait ray-traced through the published US2995980A optical prescription (5 elements in 3 groups) with a 32.1 mm entrance pupil and 1 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 US2995980A · 5 elements in 3 groups Traced surface by surface in WebGL2
Entrance Pupil Diameter 32.1 mm (at f/2.8) Controls distant background blur disc size
Corner Bokeh Roundness (90% Field) 99% at f/2.8 · 0.0 EV Mechanical vignetting (cat’s-eye vs. round corner highlights)
Background Field of View (Compression) 22° horizontal Width of the background room visible behind the subject
Upper-Body Working Distance 3.61 m Camera-to-subject distance for head-to-waist framing
Effective Focal Length (Breathing) 92.3 mm (+2.6%) Actual framing focal length at portrait distance
Depth of Field (Sharp Zone) 40 cm (3.42 m – 3.82 m) Sharp zone at wide-open aperture
Minimum Focus Distance 1 m Closest focusing distance from the sensor

Questions

How much background blur and corner cat's-eye does the Leica TELE-ELMARIT-M 90mm f/2.8 produce?

Wide open at f/2.8, the Leica TELE-ELMARIT-M 90mm f/2.8 has a 32.1 mm entrance pupil (90 mm ÷ 2.8) and 99% bokeh roundness in the 90% corner (0.0 EV corner falloff). In an upper-body portrait at 3.61 m, the sharp depth-of-field zone spans 40 cm (3.42 m to 3.82 m) with a 22° horizontal background angle of view.

Does the Leica TELE-ELMARIT-M 90mm f/2.8 show focus breathing at portrait distance?

Based on patent US2995980A, tracing the focusing group at 3.61 m gives an effective framing focal length of 92.3 mm (+2.6% vs. the nominal 90 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.

What optical design is inside the Leica TELE-ELMARIT-M 90mm f/2.8?

The patent prescription (US2995980A) specifies 5 lens elements in 3 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.