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Telephoto Lenses; Up Close And Personal Bookmark and Share

Photographers love telephoto lenses. We can’t always get close to the subjects we want to shoot, and a telephoto lens allows us to fill a significant part of the frame with them. That makes a picture with a lot of visual impact. Virtually all subjects are dramatized by the use of a telephoto—wildlife, children, sports, nature, architectural design, flowers, and more.

There are both technical and artistic considerations you need to look at when using a long lens (“long” refers to the fact that the focal length of the lens is much longer than wide angles and normal lenses). The most important aspect of using “teles” is making sure that your pictures are as sharp as possible.

Sharp Strategies
Telephoto lenses magnify distant objects so they seem closer than they really are. At the same time, however, the movement of the lens as you hand hold it is magnified. This movement is obvious when you look through the viewfinder. The heavier the lens is, and the longer the focal length it is, the more movement you’ll get. As a result, if you don’t use a fast enough shutter speed, your pictures will be blurred.

The general rule that correlates the speed of the shutter with focal length with respect to getting sharp pictures is this: The shutter speed should be at least the reciprocal of the focal length if you are hand holding the camera and lens. In other words, if you are using a 300mm telephoto, the shutter speed should be 1⁄300th of a second or faster. With a 500mm super telephoto, if the shutter speed is less than 1⁄500th of a second, there is a good chance your images will be blurred. If you are shooting from a tripod, this guideline doesn’t apply. (Read on about image stabilization lenses for a further refinement of this rule.)

The amount of light you have available is a critical part of the equation, of course. If you are shooting with a long lens in the shade, such as photo (#1), you may not be able to use a very fast shutter speed unless you bump the ISO up higher. This introduces too much digital noise, though. Therefore, we are forced to make a tough decision: We can raise the ISO and suffer the loss in image quality, or we have to risk getting less than tack sharp pictures by choosing a shutter speed that is relatively slow for the lens.

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All Photos © 2009, Jim Zuckerman, All Rights Reserved

This is why the maximum lens aperture is so important. If you have an f/2.8 lens, like the 70-200mm f/2.8 medium telephoto, in low light circumstances the light gathering ability of the large aperture means you can use a faster shutter speed. If you have a lens like the 18-200mm f/3.5-f/5.6 lens, at 200mm the largest lens opening is two full f/stops smaller than f/2.8 (f/2.8>f/4>f/5.6). With the f/5.6 aperture, you’d be forced to use 1⁄50th of a second instead of 1⁄200th. If you insisted on the faster shutter (a good thing to do in this case), then you would be forced to raise the ISO. Instead of using 200 ISO, for example, you’d be forced to shoot at 800 ISO—not a great option.

Using a tripod allows you to use a slower shutter speed providing that the subject isn’t moving. In (#2), for example, I used a 500mm lens, and even though the horses weren’t perfectly motionless a tripod would permit a shutter speed slower than 1⁄500th of a second. I wouldn’t like to go less than 1⁄125th, though. In a landscape shot like the lavender field in Provence, France (#3), nothing was moving at all (fortunately there was no wind). In this situation, any shutter speed can be used from a tripod. However, it’s vital to do two things:
1. Use the mirror lockup feature in the camera. This eliminates any possible vibration from the mirror going up and down inside the camera body. Every time you take a picture, the mirror flips up out of the way of the sensor so the light coming through the lens can form an image. After the shutter closes, the mirror flips back down so you can again see through the viewfinder.

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2. Use a cable release or the built-in self-timer feature. This prevents the camera from being jarred by your finger pushing the shutter button.

Everything that you can do to make sure the pictures are tack sharp is worth the effort. If you are not already familiar with these functions on your digital camera, it’s worth your time to learn where they are and how they work.

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Image Stabilization
As I mentioned in earlier, image stabilization is designed to minimize or even eliminate blurred images due to camera movement when telephoto lenses are hand held. When IS and VR lenses are used on a tripod, lens manufacturers suggest turning the stabilization off with some lenses. This is especially true for the original stabilized lens designs, and for some of the newer image stabilized lenses we are told that even when using a tripod, the IS and VR feature can be left on.

I have done testing with my own lenses and I’ve come to the conclusion that even if the manufacturer indicates it’s safe to leave the IS feature turned on while using a tripod, it’s best to turn it off. While some pros as well as camera company reps may disagree with me on this, every time I use a tripod and leave the IS turned on, my pictures are not as sharp as I expect them to be. This includes monopods and bean bags (such as the type used on safari in Africa), too.

Compression
Lenses don’t capture the world as we see it with our eyes. I have demonstrated the type of distortion inherent with wide angle lenses in the previous section, and now I want to explain how telephoto lenses distort reality.

There are two ways in which long lenses alter a subject or scene. First, they compress the elements that make up the composition. This means that they make the foreground seem like it is closer to the background than it really is. The longer the lens, the more compressed the image is. Second, telephoto lenses have such shallow depth of field that foreground and background elements in front of and behind the subject are often out of focus. Our eyes never see this. Both of these characteristics are the opposite of what wide angle lenses do.

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Photo (#4) is a good example of what I mean by compression. Sometimes this is referred to as “stacking”, where the elements seem to be stacked on top of each other. The black tailed deer fawn photographed in Olympic National Park in Washington was a great distance away from the mountain backdrop, but you can see that due to the compression effect it seems like that distant mountain slope is quite close. In actuality, it was about one third of a mile away. Similarly, in the photo of the group of giraffes in Namibia (#5), the animals look like they are in a fairly tight grouping, but in fact the foreground giraffe was at least 100-200 ft in front of the rear giraffe. The 300mm lens compressed the elements in the shot to make them seem like there were closer to each other than they really were.

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This stacking effect is a great tool when you want to show a mass of objects. For example, in photo (#6) the charging muddy horses I shot in France were compressed by my 500mm telephoto so they look like a fearsome mass of power, and in (#7) I used a 200mm lens to underscore the incredible density of people in Puri, India. Notice this was taken from an elevated viewpoint. Had I shot this from street level, the foreground people would have been blurred if I focused on the middle of the crowd. Also in India, with a different kind of composition, I stacked a line of rickshaws with a 200mm lens in (#8).

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Due to the compression, the distance from the front cart to the rear of the line-up seems to be less than it really was.

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