A lot of people, and almost all beginning photographers, get very excited about zoom lenses these days. They're very versatile, allowing you to capture a landscape and then do a close-up portrait the next second, without the fuss of moving from your current position or changing the lens. I insist that zoom lenses are for professionals shooting in very specific scenarios, or in any case for people who have a lot of money and have not just started learning photography. I'm about to explain why I take this point of view.

There's something in photography called composition. It's one of the basic skill areas you learn about when studying photography, along with exposure and depth of field. Composition is the planning and arrangement of elements and of the camera itself in the spatial domain. An important part of composition is how large the subject appears in the frame. There are two ways to make the subject appear larger in the frame - you either decrease the camera-to-subject distance, or you use a longer focal length to fill the frame with the subject. These two different methods can, and often do, depending on the situation, give a radically different result. More specifically, the "look" of the photo is very different with a wide-angle lens and with a telephoto lens, for a given subject size in the frame. Wider lenses tend to accentuate distances in the dimension parallel to the length of the lens, while longer lenses tend to compress them more. It happens to be the reason why telephoto lenses are often favoured for portraits and wide-angle lenses are often favoured for landscape work.

Using the above information, we can imagine an ideal scenario in which a photographer pre-visualizes the look she wants for a certain photo, and on the basis of this chooses a subject-to-camera distance which, given the size she wants the subject to appear in the frame, allows her to use the focal length required to achieve the amount of compression she is looking for. Whether she does this with a few fixed focal length lenses or a single extended range zoom lens does not really matter. Our ideal photographer will always use the same focal length and subject-to-camera distance in a given situation regardless of whether she is shooting with fixed focal lengths or zooms. This is because she has learnt and is aware of how different focal lengths affect the look, rather than the size of an object.

A beginner, however, does not know all this, and needs to learn it and be in full control of it if he is to one day be as good as our accomplished ideal photographer. If he starts out with a zoom lens, he will stand in one place and use the zoom ring instead of his feet to control the size of the subject in the frame, and in doing this will lose the bearing critical to learning the compression effects of different focal lengths, because he is not aware of what focal length he's using. It isn't a focal length anymore, it's just zoom, used as a substitute for moving. You shouldn't use the zoom ring to control the size of your subject unless you're in a specialist field, which we'll get to in a second.

Another very good point is made by Gary Voth ([link]) about composition in a more general sense: with a zoom lens you will never learn to use the viewfinder as a compositional frame. The biggest part of being a photographer is the pre-visualization process that goes on in your head before you even take out the camera, and 'seeing the frame-lines', as Leica photographers would put it, is key to the compositional part of pre-visualization.

Any other advantages associated with prime lenses? Well, yes, as a matter of fact. They tend to be cheaper than zooms because they are easier to make, and of excellent optical quality, because they are optimized to work at a single focal length, unlike a zoom lens which has to compromise to deliver fairly good performance at every focal length. They are also almost always faster, allowing you to be relatively free and unconstrained by the amount of available light. This is a huge factor to how your photography turns out. The 50mm f1.4 on my Canon T70 is three and two thirds stops faster than the 18-135mm on my Nikon D40x at 50mm. Over three stops is a world of difference! Of course, these factors aren't as important as the fact that prime lenses will teach you photography properly, and the idea that you need a fast lens to take good photographs is only maintained by equipment geeks. Nonetheless, prime lenses have all this going for them too.

So, is there a place for zoom lenses? Yes, I think so. I think zoom lenses are fine in the hands of any photographer who has already learnt the compression characteristics thing and will not abuse the zoom. Such people will take almost identical photos with zooms or primes in any one situation. They're also a huge asset to professionals in fields such as sports and nature photography, in which things happen quickly and physically moving from place to place to attain a certain subject size is unfeasible. It might even be life-threatening, if you're taking photos of tigers. These photographers need to use zoom lenses to get the job done. They are not doing it out of laziness. Note that this school is using very expensive zoom lenses, f2.8 and faster. A lens like this would cost you a small fortune.

So if you're a beginner serious about learning photography, and you have one of those zoom lenses, consider getting a cheap prime lens. Gary Voth says get a 50mm, I say get whatever you want. If you use the long end of your zoom a lot, get a telephoto. If you like landscapes, a nice wideangle. A standard 50mm is excellent for learning. But all of these will teach you the true meaning and implications of focal length. A zoom lens will not. A zoom lens is a tool that serves a specific purpose, and it is for people that understand focal length already.



Please note that I am not writing this from the point of view of someone who claims to know something. I am writing from the point of view of a vaguely enlightened beginner. These concepts have permeated my mind very early in my photographic learning curve due a series of lucky circumstances, and I felt like sharing them with the less lucky. I haven't even got a prime lens for my D40x yet (I use almost only primes on my film camera, though, and when I don't, it's out of laziness, not because I know something).