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Buying A Lens; Tips On Making The Right Choices Bookmark and Share

After you buy a good camera that allows you to change lenses, it will become obvious to you that it is not the camera that enables you to be creative in photography. It is the lenses. The features on your camera, like fast auto focus, a large LCD screen, accurate Metering modes, and various custom functions are all important, but it is the lenses that have everything to do with the artistry of the images you take.

In deciding which lenses to buy, there are various factors that come into play. I will discuss each of these factors, and then at the end of this section I will recommend which lenses I feel you should have when starting out in photography, and then I’ll give you a wish list for future purchases.

1. Cost: Lenses are expensive, and unlike computer hardware and software, their prices don’t go down over time. They usually go up. You know what your budget is, and this will be the most significant factor in making a decision. You get what you pay for, however, and as I discuss the various factors that are involved in choosing a lens, you will see that money is part of the consideration at every level.

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All Photos © 2009, Jim Zuckerman, All Rights Reserved

2. Focal Length: The focal length of a lens is the distance from the front glass element to the point in the rear of the lens where the image is focused. This definition isn’t really important, though, in terms of buying a lens. What is much more important is what type of pictures you like to take. For example, if you shoot a lot of sports, wildlife, or birds, you will need a telephoto lens to magnify the subjects in the frame so your pictures have more impact. To take the close-up of a leopard (#1), I used a powerful telephoto lens and this made a huge difference in producing a successful picture. Had the cat appeared much smaller in the frame, it wouldn’t have been a strong photo. Similarly the frame-filling shot of an Abyssinian Roller (#2), is dynamic simply because I used a telephoto lens to take this close-up photograph.

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Telephotos are defined as any lens with a focal length longer than 50mm. A 50mm lens is considered “normal” because it approximates what we see with our eyes. The longer the focal length of the lens, the more magnification you will have. If you want to fill the frame with the face of a friend who is posing 10 ft away, you can use a 200mm lens. If you want to fill a significant part of the frame with a small bird on a branch about 30 ft away, you would need a much longer telephoto like a 500mm or 600mm. As the focal length increases, so does the cost.

If you like to do landscape and/or architecture photography, you will want to get a wide angle lens. I recently spent 5 weeks shooting in Europe, for example, and most of my best shots of the classic European cathedrals, castles, and palaces were done with wide angle lenses.

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Wide angle lenses are defined as having a focal length less than 50mm. As the focal length decreases—24mm, 16mm, 10mm, etc.—the angle of view increases. In other words, the lens is able to include more in the picture. Extreme wide angle lenses have unique perspectives, and they exaggerate the graphic design in a shot dramatically.

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Study photos (#3, #4, and #5). This gives you a sense of what the various focal lengths will do for you. All of these were taken from the same shooting position, and I used a 24mm, 70mm, and 200mm focal length lens, respectively. This beautiful location is Lake Bled, Slovenia.

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3. Zoom Lenses: A zoom lens is one that offers a range of focal lengths in one lens. Zoom lenses can be constrained to the wide angle part of the focal length range, such as a 16-35mm or 10-22mm; they can be only in the telephoto range, like a 70-200mm or 200-400mm; or they can include both wide angle and telephoto. Two examples are 24-105mm and 18-200mm.

The advantage of a zoom is obvious. It’s very convenient to have a range of focal lengths built into one lens. It’s easier to carry only one lens instead of two or three, and without changing lenses you can quickly compose a scene in different ways. This can prevent you from losing a great opportunity. The disadvantage is that sometimes they tend to be a little less sharp than fixed focal length lenses. This is especially true when the zoom range is large, like in a lens that’s 18-200mm. The other disadvantage is that they tend to have smaller maximum lens apertures compared to lenses that have a fixed focal length. (See the 4th point.)

Some zooms are designed so when you change focal length, you slide a collar back and forth on the lens. Other designs give you a rubber-knurled ring that rotates to change the focal length. In considering the purchase of a zoom, I would strongly suggest the latter design. It gives you more control and it’s easier to operate.

4. Maximum Lens Aperture: All lenses have an aperture built into them. This is the opening through which light enters the camera to record an image on the digital sensor. The aperture opens and closes, and, in conjunction with the speed of the shutter, this determines whether or not your pictures are properly exposed. The maximum aperture is critical for this very important reason: In low light situations like the twilight shot of Gdansk, Poland (#6), you need to gather sufficient light with a large aperture because this enables you to use a fast enough shutter speed to ensure sharp pictures. Assuming you are hand-holding the camera (as opposed to using a tripod), a minimum shutter speed of 1⁄60th of a second is required. The large aperture must accumulate enough light to permit that speed.

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A “fast lens” is one with a large maximum aperture, such as f/2.8 or even f/1.4. The larger the lens aperture, the more it costs, the heavier it is, and the larger it is.

Here’s a real situation that happens all the time. You see bird in a tree on a cloudy day (#7), and the light level is very low in the deep shade. If your maximum lens aperture is f/5.6, the shutter speed could very well be as slow as 1⁄30th of a second if you are using a low ISO for maximum picture quality. Even with a tripod, this is too slow for this kind of subject, and the result may be a blurred picture. On the other hand, if your maximum aperture were f/2.8—two f/stops larger (f/5.6>f/4>f/2.8)—then you could use a shutter speed of 1⁄125 (1⁄30>1⁄60>1⁄125). That’s the kind of difference that can make or break a picture.

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A large maximum aperture is worth its weight in gold. In countless situations, from dim cathedrals to active children playing outside on a cloudy day, large maximum apertures mean the difference between sharp pictures and images that are soft or significantly blurred. They can also mean the difference between being forced to use a tripod to get a sharp picture and being able to hand-hold the camera. Yes, you can always increase the ISO to get that faster shutter speed, but the downside to that is there is an unwanted increase in digital noise and a degradation to overall picture quality when you do so.

Two defining aspects define all lenses: focal length and maximum aperture. Lenses are defined, for example, as 400mm f/4.5, 14mm f/2.8, or 50mm f/1.4. This gives you the most important information about the lens that will help you decide whether or not you want to buy it.

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