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Canon EF 200mm f/1.8 L USM — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published JP H01-102413A optical prescription (10 elements in 8 groups) with a 111.1 mm entrance pupil and 2.5 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | JP H01-102413A · 10 elements in 8 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 111.1 mm (at f/1.8) | Controls distant background blur disc size |
| Upper-Body Working Distance | 8.00 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 212.3 mm (+6.1%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 25 cm (7.88 m – 8.13 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 2.5 m | Closest focusing distance from the sensor |
Questions
How much background blur does the Canon EF 200mm f/1.8 L USM produce?
Wide open at f/1.8, the Canon EF 200mm f/1.8 L USM has a 111.1 mm entrance pupil (200 mm ÷ 1.8). In an upper-body portrait at 8.00 m, the sharp depth-of-field zone spans 25 cm (7.88 m to 8.13 m), while mechanical vignetting and 10 glass elements shape the out-of-focus highlights.
Does the Canon EF 200mm f/1.8 L USM show focus breathing at portrait distance?
Based on patent JP H01-102413A, tracing the focusing group at 8.00 m gives an effective framing focal length of 212.3 mm (+6.1% vs. the nominal 200 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Canon EF 200mm f/1.8 L USM?
The patent prescription (JP H01-102413A) specifies 10 lens elements in 8 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
Head-to-head patent comparisons with Canon EF 200mm f/1.8 L USM
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Also see: depth of field, bokeh, crop factor, lens compression.