Reasons to choose 645Z
Released in 2014, 645Z has about 1,452 mm² of sensor area, 51.4 MP effective resolution, and a 1,550 g body. Use these values to narrow the field, not as an overall image-quality score.
Side-by-side comparison
Pentax 645Z
vs Sony Alpha 7R II
VS
Sensor area
1,452 mm²
645Z862 mm²
Alpha 7R II- Area ratio
- 1.69:1
- Absolute difference
- 590 mm²
- Relative difference
- 68.5%
The 645Z has the larger sensor area. More area usually means greater light-gathering potential, though real image quality still depends on sensor architecture and generation.
These cameras were released 1 years apart. Consider sensor generation when comparing pixel metrics.
Key specification differences
645ZMetricAlpha 7R II
51.4 MPEffective pixels42.4 MP
44 × 33Sensor35.9 × 24
5.31 µmPixel pitch4.51 µm
28.25 µm²Pixel area20.32 µm²
3.54 MP/cm²Pixel density4.92 MP/cm²
0.79Crop factor1
1,920 × 1,080Maximum video3,840 × 2,160
1,550 gWeight625 g
SD/SDHC/SDXCStorageSD/SDHC/SDXC, Memory Stick Duo/Pro Duo/Pro-HG Duo
Rechargeable Lithium-ion Battery D-LI90 Li-ion batteryBatteryRechargeable battery NP-FW50
Amber marks the value that is generally preferable in this comparison context. It is not an overall camera score.
How to choose between these cameras
The 645Z has the larger sensor area. The Alpha 7R II has the lighter body. The 645Z has the higher effective resolution. The Alpha 7R II is the newer release. Also consider the lens system and subjects you shoot.
Reasons to choose Alpha 7R II
Released in 2015, Alpha 7R II has about 862 mm² of sensor area, 42.4 MP effective resolution, and a 625 g body. Use these values to narrow the field, not as an overall image-quality score.