Answer
What is focal length in lenses?
Focal length, measured in millimeters, determines a lens's angle of view and magnification. Short focal lengths (16-35mm) are wide; medium (35-85mm) match human vision; long (85mm+) are telephoto.
The basic ranges
- 8-15mm — fisheye, special effect
- 16-24mm — ultra-wide for landscape and interiors
- 24-35mm — wide, environmental, street, vlogging
- 35-50mm — natural, like human vision
- 50-85mm — short telephoto, portraits
- 85-135mm — classic portraits, compression
- 135-300mm — telephoto, sports, distant subjects
- 300mm+ — super-telephoto, wildlife, surveillance
Crop factor
APS-C cameras multiply effective focal length by 1.5x (1.6x on Canon). Micro Four Thirds doubles it. A 50mm on APS-C frames like a 75mm on full frame.
Compression and perspective
Short focal lengths exaggerate depth (foreground subjects look big, background tiny). Long focal lengths flatten — features compress, distance collapses. Choose focal length to control the look, not just to fill the frame.
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