Let’s talk about lenses, shall we?
One of the main selling points of a DSLR (and some types of mirrorless cameras) is the ability to change the lens on the camera if you want. But how do you make sense of all the terminology? What do all those numbers and letters mean?
Don’t worry. You’re gonna get through this.
A quick word about sensors
The size of a camera’s sensor affects how the focal length works on that camera. For more on this, check out my article on crop factors. Unless specified otherwise, the focal lengths described in this article refer to a full-frame size.
The type of lens that typically comes with an interchangeable-lens camera is often called a kit lens. These are typically zoom lenses that cover a standard range plus a little bit wider on one end and a little bit closer on the other.
One popular DSLR package includes the Canon EOS Rebel T5 with an EF-S 18-55mm IS II lens. Let’s break down what all that stuff means.
EF-S refers to the lens mount, which tells you what type of camera the lens is compatible with. In this case it’s designed to fit on any Canon camera with an APS-C sensor (the sensor most entry-level DSLRs have).
The next part of the label, 18-55mm refers to the minimum and maximum focal length. This is the distance between the front and rear focal elements and is almost always expressed in millimeters. Sometimes you’ll see a lens with only one number here. Those are called prime lenses. More on that later.
After the focal length is the aperture. Zoom lenses typically have a variable maximum aperture, as is the case with this lens. At the wide end (18mm), the maximum aperture is f/3.5, while at the close end (55mm), the maximum aperture is f/5.6. There are zoom lenses available with a fixed maximum aperture throughout the range of the lens, but those lenses tend to be more expensive.
IS stands for “Image Stabilization,” which, as the name implies, helps mitigate “camera shake.” The Roman numeral II just means it’s Canon’s second iteration of this feature. Most lens manufacturers have some version of it in their newer lenses, but each manufacturer has its own term for the feature. For example, Nikon calls it “Vibration Reduction,” so their newer lenses will have the abbreviation VR in their labels.
As you might guess by virtue of the fact that these kinds of lenses come with many cameras, this is a good “jack of all trades” lens. It will get you good enough shots most of the time. Kit lenses are meant to be versatile and lightweight. In fact, some camera users never move beyond the kit lens, and if you don’t feel the need to do so, don’t rush yourself just to look cool.
That said, the flip side of “jack of all trades” is typically “master of none.” This is not to say that you can’t get great photos with a kit lens; you certainly can. But there are some situations that a kit lens is not designed to handle, so I’d like to talk about some other lenses you might want to add to your collection as your circumstances allow.
Widely-available zoom lenses are a relatively recent phenomenon in photography, not really taking off until autofocus cameras became popular in the 1980’s. The vast majority of the iconic images of the past were taken with a prime lens, i.e., a lens with a fixed focal length. Although zoom lenses are more popular generally, there’s still a place for prime lenses today.
Prior to the prevalence of zoom lenses, the lens that many cameras came with was a 50mm prime. One popular prime is the Nikon 50mm f/1.8 lens. You’ll notice that it has a wider aperture than the zoom lens mentioned above, and indeed, that’s a significant part of these lenses’ appeal. It isn’t feasible to make zoom lenses with apertures that wide without them being very expensive.
These lenses are called “fast” primes in part because wider apertures allow you to use faster shutter speeds. If you want to know more about this, check out my previous post on the exposure triangle.
Another advantage of fast primes is that they allow for a shallow depth-of-field, which makes for clearer separation of subject and background. For this reason, fast primes are popular choices for shooting portraits. I would consider anything with a maximum aperture of f/2.8 or wider (remember, smaller numbers mean wider apertures) to be a fast prime. The best part is that 50mm primes are some of the least expensive high-quality lenses on the market, available for around $100 new.
You can also get fast primes in other focal lengths. Most lens manufacturers make an 85mm prime that some photographers like to use as a dedicated portrait lens. Many of the less expensive wide-angle lenses (anything up to 35mm) are prime lenses, which are good for landscapes.
Lenses past the 70mm mark are typically considered telephoto lenses. These are the lenses you see at sporting events and on paparazzi hiding out in the bushes.
Probably the most common focal length for telephoto zooms is 70-200mm, such as this Sony telephoto zoom. One distinguishing feature of this lens is that it has a fixed maximum aperture (f/4 in this case) throughout the range of the lens. Less expensive telephoto zooms will have a smaller maximum aperture at the long end than at the short end.
Honestly, unless you’re a professional portrait shooter, this type of lens will probably do for portraits. It’s also cheaper in most cases. The same aperture gives you a shallower depth of field as focal length increases, so you can often get perfectly good results at, say, f/5.6 with a sufficiently long lens.
As you might guess, the main purpose of a telephoto lens is to be able to capture an image without having to get so close to your subject, which is why you see paparazzi and sports photographers using these lenses. Wildlife photographers also use telephotos to avoid spooking their subjects.
Other types of lenses
The vast majority of photographic needs can be covered by the lenses mentioned so far in this article. However, there are a few kinds of lenses for more specialized purposes. I’ll briefly cover some of the ones you’re most likely to encounter.
Generally, any focal length up to 35mm is considered a wide-angle lens. As with telephotos, they are available in both zoom and prime versions. These lenses are popular for landscapes in general and night sky shots (sometimes called astrophotography) in particular. Fisheye lenses are a particular type of extremely wide lens.
Macro lenses are designed for extremely close shots. A true macro lens has a 1:1 ratio, i.e., an object appears at the same size on the sensor as it does to the eye. If you see giant-looking images of insects or flower petals, there’s a good chance those images were taken using a macro lens. They come in a variety of focal lengths, but the most common ones are in the medium telephoto range, about 90-105mm. Macro lenses are almost always primes.
These lenses are also sometimes called perspective control lenses, which describes exactly what they are intended to do. You may have noticed that when you photograph a tall building from eye level, the vertical lines appear to converge. A tilt-shift lens corrects this problem, which makes it a popular choice for serious architectural photography. You can achieve this effect to some degree with software, but it’s always better to do as much as you can in-camera.
A fun use of tilt-shift lenses is distorting perspective intentionally. For instance, you can use a tilt-shift lens to make objects appear much smaller than they are. Smashing Magazine has a great gallery of tilt-shift images.
Phew! You’ve learned about most of the lenses you’re likely to encounter as a photographer. More importantly, you’ve learned how to read lens descriptions to give you an idea of how a particular lens might be used. Maybe you’ve even got some ideas to expand the kind of work you do.