Find a lens for this look
eBay links may earn us a commission, at no extra cost to you.
Matching lenses from each maker's lineup, plus some classic medium and large format lenses. Email me if something is wrong or missing.
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 |
| Corner Bokeh Roundness (90% Field) | 98% at f/2 · -0.1 EV | Mechanical vignetting (cat’s-eye vs. round corner highlights) |
| Background Field of View (Compression) | 22° horizontal | Width of the background room visible behind the subject |
| 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 and corner cat's-eye 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) and 98% bokeh roundness in the 90% corner (-0.1 EV corner falloff). 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) with a 22° horizontal background angle of view.
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.
Related comparisons
- Leica APO-Summicron-M 90mm f/2 ASPH. vs. Leica Summilux-M 90mm f/1.5 ASPH.
- Leica Summilux-M 90mm f/1.5 ASPH.
- Leica TELE-ELMARIT-M 90mm f/2.8
- Leica Macro-Elmar-M 90mm f/4
Compare with similar portrait lenses
- Canon RF 85mm F2 MACRO IS STM
- Sony FE 85mm f/1.8
- Nikon NIKKOR Z 85mm f/1.8 S
- Nikon AF 85mm f/1.8D
- Sony FE 90mm F2.8 Macro G OSS
- Nikon 55mm f/1.2 AI
Also see: depth of field, bokeh, crop factor, lens compression.