The focal length of telephoto lenses range from about 28mm to 800mm and above. The longer the focal length the more detail the lens can capture from a distance. It also means the lens is bigger, heavier and more expensive. Telephoto lenses can be separated into three types:
1. Short Telephoto Lenses - These range from 85mm to 135mm (your mileage may vary) and are perfect for shooting candid shots and portraits. For example, the short telephoto lenses allow you to take stunning pictures at weddings where you're close to your subjects yet you don't want to intrude in the process. These shorter lenses are lightweight, compact and easier to hand, which allows for fast shooting.
2. Medium Telephoto Lenses - Ranging from 135mm to 300mm, medium lenses are ideal for action and sport photographers who -- for example -- are standing on the sidelines but need to get close to where the action is. This type of photography requires proper aperture setting to minimize blur when shooting fast-moving subjects.
3. Super Telephoto Lenses - Typically, these types of telephoto lenses -- which range from 300mm and beyond -- are used only in professional nature, wildlife and sports photography, and are not used for portraits.