Many amateur photographers have the same question: should I use a zoom lens or should I use a prime lens? The correct answer is that both should be used depending on conditions, and both offer advantages that can be exploited by the photographer willing to accept certain trade offs in performance.

A zoom lens is a lens that uses movable internal mechanism to produce a variable focal length. They are versatile in that objects both near and far can be photographed. Due to this fact, a camera using a good zoom lenses requires fewer lens changes and the camera and lens usually stay internally cleaner as a result. This benefit can be negated, however, if the zoom lens construction is one that telescopes in and out. This can literally pump dirty air into the mechanism like an accordion. On the other hand, another benefit is that the photographer can more suitably compose and frame the photo when it is taken. This helps minimize cropping and additional work during post-processing.

Since a zoom lens has more moving parts than a prime lens, a small amount of sharpness is lost due to slight misalignment issues or inherent "looseness" of the lens train. This problem can vary in extremes, as a high quality zoom lens can rival a prime lens in sharpness, whereas a low quality zoom lens can be nearly useless with odd aberrations extending all the way to the field edge. Another drawback of a zoom lens is that they are generally slower than a prime lens, as the internal zoom mechanism must be sized for the longest focal length available. In other words, a good focal length apparatus at long focal lengths doesn't necessarily convert to a good focal length apparatus at short focal lengths. Zoom lenses are, in effect, the jack of all trades. They are capable of being used over a wide range of operating conditions at good to average picture quality.

Prime or fixed lenses do not have an adjustable focal length. Usually the only controls available might be focus and f-stop. They are usually less expensive than comparable zoom lenses due to simpler construction, have better optical quality, and are usually faster. They usually have a wider field of view for a given focal length and less glass in the optical train to absorb light. On the downside, they are less versatile and require more lens changes. Prime lenses are the masters of photographic quality. They are expected to perform over a very limited operating range, but within that range, their performance is flawless.

So which is best, the versatile zoom or the precision prime lens? It all depends on the personal skill, monetary resources, and interests of the photographer. For someone shooting action shots with varying distances to the subject, or for someone on a limited budget, a single zoom lens is ideal. In contrast, a photographer that shoots still object or subjects at fixed distances may opt for two or three prime lenses with a range of focal lengths to get that perfectly composed shot with center to edge sharpness.

At any rate, zoom and prime lenses both have a place in the camera bag of every photographer.