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Once you’ve decided which camera to buy, your next problem is to decide what lenses you will need. There’s no single “best set” of lenses for everyone since the choice depends on your budget and your needs.
Lenses are classified by their field of view. A wideangle lens has a wide field of view, while a telephoto lens has a narrow field of view. Field of view depends not only on focal length, but also on the format size. This means that a lens of a given focal length (say 35mm) might we classified as a wideangle lens when used on a full frame camera, but a normal lens when used on an APS-C crop format camera.
The table below splits lenses into 6 categories based on their horizontal angle of view. The classifications are slightly arbitrary but nevertheless useful.
Horizontal Angle of View (degrees)
With regards to the applications, these are just general common uses. You can pretty much use any lens in any application, i.e. you can shoot landscapes with a 400mm lens or wildlife with a 35mm lens, it’s just that you probably won’t be doing either very often.
In the following article I’ll probably mention Canon lenses more than lenses from other manufacturers simply because I use Canon equipment and so I’m more familiar with their products. This should not be taken as an indication that Canon lenses are “best”. Most other lens manufacturers will have similar lenses in their lineup and this article is about selecting lenses based on focal length and aperture so it is applicable no matter what brand of camera you own.
Primes and Zooms
Prime lenses have a fixed focal length, while zoom lenses have a variable focal length. Each has it’s own set of advantages and disadvantages.
Advantages of Prime Lenses
Usually faster than zooms. The fastest current primes are f/1.2, but almost all are f/2.8 and faster. In most camera systems, the fastest zooms available are f/2.8 (though Olympus have an f/2 zoom for their “four-thirds” format cameras). Fast lenses are not only useful in low light, but can also be used to throw a background out of focus by shooting at the maximum aperture and minimizing depth of field.
Low distortion. Since they can be optimized for a single focal length, geometric aberrations can be more easily minimized.
Usually smaller than zooms, at least smaller than fast high quality zooms
Versatility. It’s much easier and faster to change focal length with a zoom lens then it is to remove a prime lens and replace it with a prime lens of a different focal length.
Along with versatility, not having to change lenses means that there is less change of dust getting into the camera and landing on the sensor.
Cost. Although a high quality, fast zoom may be expensive, it’s still probably cheaper than a selection of prime lenses which cover the same range.
Size – Although a prime may be smaller than a high quality zoom covering the same focal length, the zoom is probably smaller (and lighter) than a set of primes which cover the range of the zoom.
Most photographers chose zooms except when they need an ultra fast lens. While the fastest zooms are f/2.8, primes can be as fast as f/1.2 and many are f/1.4 or f/2. The lower distortion of primes can be an advantage for architectural photography where you need straight lines to be straight, though in today’s digital world, distortion can often be corrected in Photoshop.
Fast vs. Slow
The maximum aperture of most lenses falls somewhere in the range between f/1.2 and f/5.6, though there are a few 3rd party zooms which have a maximum aperture of f/6.3 at the long end of their range.
Fast lenses are larger, heavier and more expensive then their slower counterparts, so that a Canon EF 400mm f/5.6L USM, (compare prices) is 10” long and weighs 2.8 lbs, while a Canon EF 400mm f/2.8L IS USM, (compare prices) is 14” long and weighs 11.7 lbs. In this case both lenses are very sharp, so the extra two stops of lens speed cost you around $5600 and mean you have to carry around and extra 9 lbs in weight!
At the other end of the lens range, consider the price difference beteeen a Canon EF 50mm f/1.2 L USM, (compare prices) (review), a Canon EF 50mm f/1.4 USM, (compare prices) (review) and a Canon EF 50mm f/1.8 II, (compare prices) (review). When stopped down to maybe f/4 or f/5.6 there won’t be a whole lot of difference in optical performance. There may be some, but the f/1.2 lens won’t be 14x sharper, even though it costs 14x as much. The main advantage of the f/1.2 lens is that it can be used at f/1.2. Pretty much the same goes for the f/1.4. Now in this particular case, the f/1.2 lens is better built and has Canon’s ring USM focusing system, the f/1.4 uses a mico USM motor and the f/1.8 is all plastic (including the mount) and uses a regular (AFD) focusing motor.
Should you buy a fast lens or a slow lens? I’d say that a fast lens only makes real sense if you intend to shoot it wide open. If you’re going to be shooting at f/8, you’ll be paying a lot more for capabilities you never use. The fast lens might be a little sharper even stopped down, but the difference may not be enough to justify the additional cost.
So if you intend to shoot landscape with a 24mm lens, you’ll probably be shooting stopped down to around f/8 in order to get good depth of field, so you might be just as well off with the Canon EF 24mm f/2.8, (compare prices) as with the more expensive Canon EF 24mm f/1.4L II USM, (compare prices) (review). On the other hand, if you’re doing a lot of work shooting in confined dark places, like night clubs, you might want to chose the 24/1.4L over the 24/2.8 because it’s a full two stops faster.