Portrait At-a-Glance Comparison (Upper Body Framing)
| Optical & Portrait Metric | Canon RF 135mm F1.8 L IS USM | Canon 135mm f/2 L | What It Means in Practice |
|---|---|---|---|
| Upper-Body Working Distance | 5.40 m | 5.40 m | Identical working distance—both frame an upper-body portrait from the exact same spot. |
| Effective Focal Length (Breathing) | 132.7 mm (-1.7%) | 138.8 mm (+2.8%) | At 5.4 m, Canon RF 135mm F1.8 L IS USM frames like a 132.7 mm lens while Canon 135mm f/2 L frames like a 138.8 mm lens. |
| Depth of Field (Sharp Zone) | 25 cm (5.28 m – 5.53 m) | 28 cm (5.27 m – 5.55 m) | The Canon RF 135mm F1.8 L IS USM has a 10% thinner focus zone (25 cm vs. 28 cm)—requiring more precise eye focus. |
| Entrance Pupil Diameter | 75.0 mm (f/1.8) | 67.5 mm (f/2) | Distant background blur discs are 11% larger on the Canon RF 135mm F1.8 L IS USM. |
| Minimum Focus Distance | 0.7 m | 0.9 m | Canon RF 135mm F1.8 L IS USM focuses 20 cm closer (0.7 m vs. 0.9 m) for tighter close-ups. |
| Patent Prescription | US20230213745A1 (17/12) | JP2018-049102A (10/8) | Published optical prescriptions traced in the 3D simulator above. |