The focal length of a lens is the distance between the lens and the sensor when the lens is focused at infinity.

The shorter the focal length, the wider the angle of view. This is because a shorter focal length lens has a wider field of view.

The longer the focal length, the greater the magnification. This is because a longer focal length lens brings the subject closer to the camera, making it appear larger.

85mm is a good focal length for portraits because it provides a flattering perspective and allows for a shallow depth of field.

16mm is a good focal length for landscapes because it allows for a wide angle of view, which is ideal for capturing expansive scenes.

400mm is a good focal length for wildlife photography because it allows for a long reach, which is necessary for photographing animals that are far away.

70-200mm is a good focal length for sports photography because it provides a versatile range of focal lengths that can be used to capture both wide shots and close-ups.

100mm is a good focal length for macro photography because it provides a good working distance, which is important for avoiding shadows and reflections.

A prime lens has a fixed focal length, while a zoom lens has a variable focal length. Prime lenses are typically lighter and more compact than zoom lenses, and they often have a faster maximum aperture.

Prime lenses are sharper than zoom lenses, they have a faster maximum aperture, and they are lighter and more compact than zoom lenses.

Prime lenses are less versatile than zoom lenses, they are more expensive than zoom lenses, and they are not as good in low-light conditions as zoom lenses.

Zoom lenses are more versatile than prime lenses, they are less expensive than prime lenses, and they are better in low-light conditions than prime lenses.

Zoom lenses are not as sharp as prime lenses, they have a slower maximum aperture, and they are heavier and bulkier than prime lenses.

The type of lens that is best for beginners depends on the type of photography they want to do. If they are interested in portrait photography, a prime lens might be a good choice. If they are interested in landscape photography, a zoom lens might be a better choice.

The most important thing to consider when choosing a focal length is the type of photography you want to do, the size of your sensor, and the budget you have.