All about telephoto lenses :: Digital Photo Secrets
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All about telephoto lenses

by David Peterson 0 comments

When I was a new photographer, my dream lens was a 500 mm telephoto, like you always see sports photographers using on the sidelines of professional football games. To me, being able to get super close to fast action was the Holy Grail of photography. But back then I didn't quite understand the subtle nuances of telephoto lenses that all photographers really need to know in order to get the most out of the lenses they have, and make the right decisions about the lenses they need. The truth is that telephoto lenses need not be overly long or overly expensive to be effective. It really depends on what kind of photography you are into, and the sorts of pictures that you plan to take.

Now, what about those ginormous lenses that I once admired on the sidelines of sporting events? Those are great lenses indeed, but they are exceedingly expensive—probably out of reach for the average non-Sports Illustrated or National Geographic photographer. They're also unnecessary for the vast majority of what the average person is likely to want to do with a telephoto lens.

Fun facts about telephoto lenses

Telephoto lenses like those you see on the sidelines at a professional sporting event are not only expensive, they're unwieldy. To manage one, you need to have a tripod that can support not only the camera but the weight of the lens. And because those lenses are so big and heavy, you need to to shoot with very fast shutter speeds in order to avoid lens-related camera shake. So unless someone's paying you the big bucks to use a super long telephoto lens to shoot sports or wildlife, you're probably better off purchasing something a little smaller that is meant for the consumer market, at least until you finally make that jump into professional photography.

So when do you need a zoom lens? The average photographer doesn't really need much of a zoom lens at all, unless sports or wildlife photography really is a deep passion. But if you mostly shoot family events, or you travel a lot and like to take your camera with you, I think you're going to find that a super long telephoto lens just isn't that useful. Shop for something mid-range instead—consider a 75 to 300 or 55 to 250 mm lens instead. You can pick one of these up for a reasonably low price and can still have all the fun of using a telephoto without the expense and weight of a super long lens

Even a mid-range zoom lens does have some caveats attached, however. Mid-range zooms are heavier than kit lenses are, so you can't use them with slower shutter speeds. Most modern zoom lenses have some kind of image stabilization technology, which means that they perform better at slower shutter speeds than their counterparts did from a couple of decades ago, but you do still need to be aware of their limitations. The old rule was that you should never shoot at a shutter speed with a bottom number that is smaller then the focal length of the lens. For example, if you're shooting at maximum zoom with a 55 to 250mm lens, you don't want to shoot any slower than 1/250 or you'll get camera shake. That rule has actually changed quite a bit since the introduction of image stabilization technology, and you can now get away with shooting a few stops slower than the old rule said you could, depending on how well your camera performs. You won't really know until you do some tests, so I suggest starting with that 1/f rule and working backwards to see how much blur you get at decreasingly slow shutter speeds. So for example, start with your 250mm zoom lens at maximum zoom with a shutter speed of 1/250. Then try maximum zoom with a shutter speed of 1/125—make sure image stabilization is turned on—and then shoot a third photo at 1/60. Now open up all three images in post-processing and zoom in to 100% magnification. Compare the details. Look at areas which you know should be sharp that are close to or at your focal point, and see when camera shake starts to become noticeable. Remember that you still need to take precautions such as holding your camera as steady as possible during those exposures, but those close up views should let you know when you need to move away from handholding and mount your camera on a tripod instead.

The other thing to keep in mind about consumer zoom lenses is that they have variable apertures. So while your maximum aperture may be f/4 when fully zoomed out, your aperture may change it to f/5.6, for example, at maximum zoom. The reason why this happens is very simple—as you lengthen your lens, the aperture doesn't technically change, but the physical distance that light has to travel across the longer focal length does change, so less light overall reaches your camera's sensor. So that reduction in aperture is effective—it impacts your photos in the same way as a physical reduction in aperture does.

Lenses with fixed focal lengths are available if you want to pay a premium. The difference in price has to do with the construction of the lens. A fixed aperture lens has a barrel that does not lengthen or shorten when you zoom, so the aperture will stay the same as you change focal length. In order to construct a lens in this way, you need a lot more material so you end up with a much heavier and more expensive lens. This is usually coupled with better quality glass and faster autofocus, which adds up to a much higher price. That is not to say it's not a worthwhile investment and if you find that you love telephoto photography it's certainly not going to be wasted money. But spending that much on a telephoto lens is not something you really have to do unless you are very serious about those long-distance photographs.

When to use a telephoto lens

We already mentioned sports photography and wildlife photography—in both cases there is a physical reason why you might need the extra length. Wild animals are elusive and they don't tend to like large people with large cameras getting close to them. So you get better wildlife photographs if you have longer lenses, and this is especially true for fast, flighty animals like birds.

  • Nikon D4S
  • 800
  • f/8.0
  • 0.001 sec (1/1000)
  • 500 mm

Purple Rumped Sunbird by Flickr user Koshyk

Sports photography requires long telephoto lenses because even if you're lucky enough to be standing on the sidelines, a sports arena is a big place and unless you happen to be right next to the action, you're going to need that extra reach in order to capture it or fill the frame with it. But sports and wildlife are by no means the only two situations where you might want to break out that zoom lens. Zoom lenses are also handy for stealth photography—let's say you have kids who are particularly reluctant photography subjects. A zoom lens will let you hang back and capture photographs of them without them being too aware or bothered by the presence of your camera. And telephoto lenses are also great for really any object that you can't get physically close to. Animals in zoos are a great example, as are any objects that you might be physically separated from by some sort of barrier such as a fence or a large body of water. And just as you can use a wide angle lens to exaggerate the distance between objects, you can also use a telephoto lens to decrease the perceived distance between objects. Let's say you're photographing a forest and you want it to look denser than it does in real life. Stand back some distance from the forest and zoom in—your zoom lens will make the trees appear closer together, which can make the forest look a lot thicker and heavier.

One thing to keep in mind when you're photographing people with a wide angle lens is that that decrease-in-distance effect can also translate to human features. While a wide angle lens can make a person's features look disproportionately large, a telephoto lens can create an almost flattening effect across the face. The effect is not as unflattering as the effect of a wide-angle lens on a human face, in fact it's probably not really something that your subject is likely to notice when viewing photographs of himself, however, it is important to be aware of potential for this happening as it can be a less-than-perfect representation of that individual.

  • Nikon D5000
  • 2000
  • f/5.6
  • 0.002 sec (1/500)
  • 220 mm

Djarum Black by Flickr user Neil. Moralee

Conclusion

I do believe that a telephoto lens is something every hobby photographer should have, even if you don't have aspirations to become a professional. Telephoto lenses will give you photographic possibilities that you just don't have with a basic, mid-range kit lens, so it's one of those things that you should probably add to your wish list for purchase as soon as it is within your budget. Then you can move on to a pro-quality zoom lens if you find that wildlife photography or sports photography is your passion. Until then, you're free to experiment with that consumer model variable-aperture telephoto lens, and proximity to your subject will never again be a barrier to capturing a great photo.

Summary:

  1. Testing your telephoto
    • Engage image stabilization
    • Take test shots at decreasing shutter speeds
    • View at 100 percent to find camera shake
  2. When to use a telephoto
    • Sports photography
    • Wildlife photography
    • Stealth photography
    • Subjects you can't get physically close to
    • To create distortion/make objects appear closer together

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Difficulty:
Beginner
Length:
13 minutes
About David Peterson
David Peterson is the creator of Digital Photo Secrets, and the Photography Dash and loves teaching photography to fellow photographers all around the world. You can follow him on Twitter at @dphotosecrets or on Google+.