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Sony FE 300mm F2.8 GM OSS — Bokeh & Optical Ray-Tracing Simulator
Interactive 3D portrait ray-traced through the published US4518229A optical prescription (10 elements in 8 groups) with a 107.1 mm entrance pupil and 2 m minimum focus.
Optical & Portrait Specifications (Upper Body Framing)
| Optical & Portrait Metric | Measured / Patent Value | What It Means in Practice |
|---|---|---|
| Patent Prescription | US4518229A · 10 elements in 8 groups | Traced surface by surface in WebGL2 |
| Entrance Pupil Diameter | 107.1 mm (at f/2.8) | Controls distant background blur disc size |
| Corner Bokeh Roundness (90% Field) | 77% at f/2.8 (≥86% from f/4) · -0.5 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 7° horizontal | Width of the background room visible behind the subject |
| Upper-Body Working Distance | 12.00 m | Camera-to-subject distance for head-to-waist framing |
| Effective Focal Length (Breathing) | 294.0 mm (-2.0%) | Actual framing focal length at portrait distance |
| Depth of Field (Sharp Zone) | 39 cm (12 m – 12 m) | Sharp zone at wide-open aperture |
| Minimum Focus Distance | 2 m | Closest focusing distance from the sensor |
Questions
How much background blur and corner cat's-eye does the Sony FE 300mm F2.8 GM OSS produce?
Wide open at f/2.8, the Sony FE 300mm F2.8 GM OSS has a 107.1 mm entrance pupil (300 mm ÷ 2.8) and 77% bokeh roundness in the 90% corner (-0.5 EV corner falloff, reaching ≥86% roundness from f/4). In an upper-body portrait at 12.00 m, the sharp depth-of-field zone spans 39 cm (12 m to 12 m) with a 7° horizontal background angle of view.
Does the Sony FE 300mm F2.8 GM OSS show focus breathing at portrait distance?
Based on patent US4518229A, tracing the focusing group at 12.00 m gives an effective framing focal length of 294.0 mm (-2.0% vs. the nominal 300 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.
What optical design is inside the Sony FE 300mm F2.8 GM OSS?
The patent prescription (US4518229A) specifies 10 lens elements in 8 groups. The interactive Optical X-Ray above traces rays through every surface in real time.
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Compare with similar portrait lenses
- Nikon 300mm f/2.8 AF-S II FX
- Canon 300mm f/2.8 L IS
- Leica APO-Telyt-R 280mm f/2.8
- Nikon 300mm f/2 ED IF
- Canon 300mm f/4 L IS
- Canon EF 200mm f/1.8 L USM
Also see: depth of field, bokeh, crop factor, lens compression.