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OM System M.Zuiko Digital ED 75mm F1.8 — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published JP 2013-161076 A optical prescription (10 elements in 9 groups) with a 41.7 mm entrance pupil and 0.85 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | JP 2013-161076 A · 10 elements in 9 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 41.7 mm (at f/1.8) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 87% at f/1.8 · -0.2 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 13° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 6.24 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 75.9 mm (+1.3%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 53 cm (5.99 m – 6.52 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 0.85 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the OM System M.Zuiko Digital ED 75mm F1.8 produce?
Wide open at f/1.8, the OM System M.Zuiko Digital ED 75mm F1.8 has a 41.7 mm entrance pupil (75 mm ÷ 1.8) and 87% bokeh roundness in the 90% corner (-0.2 EV corner falloff). In an upper-body portrait at 6.24 m, the sharp depth-of-field zone spans 53 cm (5.99 m to 6.52 m) with a 13° horizontal background angle of view.
Does the OM System M.Zuiko Digital ED 75mm F1.8 show focus breathing at portrait distance?
Based on patent JP 2013-161076 A, tracing the focusing group at 6.24 m gives an effective framing focal length of 75.9 mm (+1.3% vs. the nominal 75 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the OM System M.Zuiko Digital ED 75mm F1.8?
The patent prescription (JP 2013-161076 A) specifies 10 lens elements in 9 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
Related comparisons
- 75mm APS-C vs 110mm full frame focal length comparison
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- 80mm medium format vs 85mm full frame focal length comparison
Compare with similar portrait lenses
- Sony FE 85mm f/1.8
- Nikon NIKKOR Z 85mm f/1.8 S
- Nikon AF 85mm f/1.8D
- Fujifilm GF 80mm F1.7 R WR
- Canon 85mm f/1.8
- Nikon 58mm f/1.4 G FX
Also see: depth of field, bokeh, crop factor, lens compression.