Camera Field of View
理解する Lens Angles
Learn About FOVField of view (FOV) is the angle of the scene your camera captures. 理解する FOV helps choose the right lens for landscapes, portraits, or action—and explains why the same focal length produces different results on different cameras.
Lens Categories by Field of View
| Category | Focal Length (FF) | Diagonal FOV | Typical Use |
|---|---|---|---|
| Fisheye | 8-16mm | 180-100° | Creative, action cams |
| Ultra-wide | 14-24mm | 114-84° | Architecture, landscapes |
| Wide-angle | 24-35mm | 84-63° | Street, environmental |
| Standard | 40-60mm | 57-40° | General purpose |
| Short telephoto | 70-105mm | 34-23° | Portraits |
| Medium telephoto | 135-200mm | 18-12° | Sports, events |
| Super telephoto | 300-800mm | 8-3° | Wildlife, astronomy |
Focal lengths shown are for full-frame (35mm) sensors.
Sensor Size and Crop Factor
The same focal length produces different FOV on different sensor sizes.
Common Sensor Sizes
| Format | Dimensions | Crop Factor |
|---|---|---|
| Medium Format | 44×33mm (typical) | 0.79× |
| Full Frame (35mm) | 36×24mm | 1.0× |
| APS-C (Canon) | 22.3×14.9mm | 1.6× |
| APS-C (Nikon/Sony) | 23.5×15.6mm | 1.5× |
| Micro Four Thirds | 17.3×13mm | 2.0× |
| 1-inch | 13.2×8.8mm | 2.7× |
| Smartphone (typical) | ~6×4.5mm | ~6× |
Equivalent Focal Length
Equivalent FL = Actual FL × Crop Factor
A 50mm lens on APS-C (1.5×) gives the same FOV as a 75mm on full-frame.
FOV Measurements
Field of view can be measured in three ways:
Diagonal FOV
- Corner to corner of the frame
- Largest angle measurement
- Most commonly cited specification
Horizontal FOV
- Side to side of the frame
- Important for panoramas and video
- About 80% of diagonal for 3:2 format
Vertical FOV
- 変換先p to bottom of the frame
- Smallest of the three
- About 54% of diagonal for 3:2 format
Example: 50mm on Full Frame
- Diagonal: 46.8°
- Horizontal: 39.6°
- Vertical: 27.0°
Video and Cinema FOV
Video applications often specify horizontal FOV.
Common Video FOVs
- Ultra-wide (GoPro): 120-170° diagonal
- Wide: 90-100° diagonal
- Linear (corrected): 80-90° diagonal
- Medium: 65-75° diagonal
- Narrow: 50-60° diagonal
Aspect Ratio Impact
- Wider aspect ratios (21:9) have larger horizontal FOV
- Same diagonal FOV covers different horizontal area
- Anamorphic lenses create wide FOV with different characteristics
VR and Gaming FOV
Virtual reality headsets prioritize immersion through wide FOV.
VR Headset FOVs
- Early VR: 90-100°
- Current mainstream: 100-120°
- High-end: 120-140°
- Human peripheral: ~180° (the goal)
Gaming FOV Settings
- Lower FOV (60-75°): Less distortion, feels "zoomed in"
- Standard FOV (90°): Common default
- Higher FOV (100-120°): More peripheral awareness, some distortion
- Personal preference and monitor distance affect ideal setting
Security Cameras
Security camera specifications emphasize coverage area.
Typical Security Camera FOVs
- Wide-angle: 90-120° (room coverage)
- Standard: 60-90° (hallways, entries)
- Narrow: 30-60° (specific areas)
- PTZ range: Variable, often 60° to 2°
Coverage Calculation
At distance D, horizontal coverage width:
Width = 2 × D × tan(HFOV/2)
Example: 90° HFOV at 10m covers 20m width
Calculating FOV
変換元 Focal Length and Sensor Size
Diagonal FOV = 2 × arctan(diagonal / (2 × focal length))
Example: 35mm Full Frame
- Sensor diagonal: √(36² + 24²) = 43.27mm
- Focal length: 35mm
- FOV = 2 × arctan(43.27 / 70) = 2 × arctan(0.618) = 63.4°
Finding Focal Length for Desired FOV
Focal length = sensor size / (2 × tan(FOV/2))
まとめ
Field of view is the angular extent captured by a camera, determined by both focal length and sensor size. Wide FOV lenses (short focal length) capture expansive scenes but with potential distortion; narrow FOV lenses (long focal length) isolate subjects with background compression. 理解する crop factors is essential when comparing lenses across different camera systems. FOV specifications are important across photography, videography, VR, gaming, and security applications.