The Pentax 645D is 34 mm wider, 47.9 mm taller, 84.7 mm deeper and 1,111 g heavier than the Olympus PEN E-P3.
| Olympus PEN E-P3 | Pentax 645D | |
|---|---|---|
| Size (W × H × D) | 122 × 69.1 × 34.3 mm | 156 × 117 × 119 mm |
| Weight | 369 g | 1,480 g |
| Lens | Micro Four Thirds | — |
| Sensor | Four Thirds | — |
| Announced | 2011 | 2010 |