Understanding Focal Lengths

Focal Length: 18mm
Aperture: f/16.0
Shutter Speed:.3
ISO: 800

Focal Length: 24mm
Aperture: f/16.0
Shutter Speed: .3
ISO: 800

Focal Length: 35mm
Aperture: f/16.0
Shutter Speed: 1/5
ISO: 800

Focal Length: 55mm
Aperture: f/16.0
Shutter Speed: 1/5
ISO: 800

Focal Length is represented in millimeters and is the basic description of a photographic lens. Prime lenses are for larger aperture. Zoom lens reduce the number of times you need to change the lens.