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Leica APO-Summicron-M 90mm f/2 ASPH. — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published US3076383A optical prescription (5 elements in 4 groups) with a 45.0 mm entrance pupil and 1 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | US3076383A · 5 elements in 4 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 45.0 mm (at f/2) | Controls distant background blur disc size |
| 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) | 28 cm (3.47 m – 3.75 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 1 m | Closest focusing distance from the sensor |
Questions
How much background blur does the Leica APO-Summicron-M 90mm f/2 ASPH. produce?
Wide open at f/2, the Leica APO-Summicron-M 90mm f/2 ASPH. has a 45.0 mm entrance pupil (90 mm ÷ 2). In an upper-body portrait at 3.61 m, the sharp depth-of-field zone spans 28 cm (3.47 m to 3.75 m), while mechanical vignetting and 5 glass elements shape the out-of-focus highlights.
Does the Leica APO-Summicron-M 90mm f/2 ASPH. show focus breathing at portrait distance?
Based on patent US3076383A, 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 APO-Summicron-M 90mm f/2 ASPH.?
The patent prescription (US3076383A) specifies 5 lens elements in 4 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
Head-to-head patent comparisons with Leica APO-Summicron-M 90mm f/2 ASPH.
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Also see: depth of field, bokeh, crop factor, lens compression.