A zoom lens has a variable focal length. It can be adjusted to cover a range, from wide to telephoto. A 24-70mm zoom covers wide-angle to short telephoto. A 70-200mm zoom covers medium to long telephoto. Zoom lenses are versatile. They replace multiple prime lenses. They are convenient for travel, events, and any situation where changing lenses is impractical. A zoom lens is not as sharp as a prime lens at the same focal length, and it is usually slower, with a narrower maximum aperture. But the convenience is worth it for many photographers.

Zoom lenses come in two main types. Standard zooms cover a moderate range, like 24-70mm or 18-55mm. Telephoto zooms cover a longer range, like 70-200mm or 100-400mm. Superzooms cover a very wide range, like 18-300mm, but they compromise on sharpness and speed. The maximum aperture of a zoom lens can be constant or variable. A constant aperture, like f/2.8, stays the same throughout the zoom range. A variable aperture, like f/3.5-5.6, changes as you zoom. Constant aperture lenses are more expensive and more desirable. Zoom lenses are the workhorses of photography. They are not always the best tool, but they are often the most practical.

Zoom lens types

• Standard. 24-70mm, everyday use.
• Telephoto. 70-200mm, portraits and events.
• Superzoom. 18-300mm, travel and convenience.
• Wide-angle. 16-35mm, landscapes and interiors.
• Constant aperture. f/2.8 throughout the range.

A zoom lens is not the same as a prime lens. A prime has a fixed focal length. A zoom has a variable one. Both are tools. The best choice depends on how you shoot.