Canon EF 50mm f/1.8 II — Bokeh & Optical Ray-Tracing Simulator

Interactive 3D portrait ray-traced through the published JP S62-087922A optical prescription (6 elements in 5 groups) with a 27.8 mm entrance pupil and 0.45 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	JP S62-087922A · 6 elements in 5 groups	Traced surface by surface in WebGL2
Entrance Pupil Diameter	27.8 mm (at f/1.8)	Controls distant background blur disc size
Upper-Body Working Distance	2.01 m	Camera-to-subject distance for head-to-waist framing
Effective Focal Length (Breathing)	50.7 mm (+1.4%)	Actual framing focal length at portrait distance
Depth of Field (Sharp Zone)	26 cm (1.89 m – 2.15 m)	Sharp zone at wide-open aperture
Minimum Focus Distance	0.45 m	Closest focusing distance from the sensor

Questions

How much background blur does the Canon EF 50mm f/1.8 II produce?

Wide open at f/1.8, the Canon EF 50mm f/1.8 II has a 27.8 mm entrance pupil (50 mm ÷ 1.8). In an upper-body portrait at 2.01 m, the sharp depth-of-field zone spans 26 cm (1.89 m to 2.15 m), while mechanical vignetting and 6 glass elements shape the out-of-focus highlights.

Does the Canon EF 50mm f/1.8 II show focus breathing at portrait distance?

Based on patent JP S62-087922A, tracing the focusing group at 2.01 m gives an effective framing focal length of 50.7 mm (+1.4% vs. the nominal 50 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.

What optical design is inside the Canon EF 50mm f/1.8 II?

The patent prescription (JP S62-087922A) specifies 6 lens elements in 5 groups. The interactive Optical X-Ray above traces rays through every surface in real time.

Head-to-head patent comparisons with Canon EF 50mm f/1.8 II

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