Micro Four Thirds Sensor (2.0× Crop)
Direct Answer
The Micro Four Thirds (MFT) Sensor (measuring 17.3 × 13.0 mm with an active area of 224.9 mm² and a 21.64 mm diagonal) is an open mirrorless standard established by Olympus and Panasonic, featuring an exact 2.0× crop factor and a native 4:3 aspect ratio. Equal to exactly half the diagonal of 35mm full frame, focal length calculations are simple integers (25mm = 50mm equivalent).
Source: Four Thirds System Standard (Olympus Corp. & Panasonic Corp.) / CIPA
Specs
| Width × Height | 17.3 × 13.0 mm (0.681 × 0.512 in) |
| Diagonal Dimension | 21.64 mm (exactly half of 35mm full frame's 43.27 mm diagonal) |
| Active Surface Area | 224.9 mm² (approx. 26.0% of 35mm full frame) |
| Crop Factor | 2.00× exactly |
| Native Aspect Ratio | 4 : 3 (1.33 : 1) |
| Focal Length Equivalence Formula | Focal length × 2.0 (e.g. 12-40mm f/2.8 lens ≈ 24-80mm f/5.6 full-frame field/DoF) |
| Camera Systems | OM System OM-1 / OM-5, Panasonic Lumix GH6 / G9 II / BGH1, Blackmagic Pocket Cinema Camera 4K |
Telephoto Reach and Telecentric Lens Design
Because of the 2.0× crop factor, a compact $300\text{ mm}$ MFT telephoto lens captures the identical field of view of a massive $600\text{ mm}$ full-frame super-telephoto lens at a fraction of the physical weight and cost. The 4/3 optical design enforces near-telecentric light incidence, ensuring light rays strike sensor photodiodes at near-perpendicular angles to eliminate corner vignetting.