Making the most of telephoto zoom lenses

The compression effect of a 200mm focal length on a camera with an APS-C sensor, which gives the equivalent of 320mm in 35mm format. The layered areas within the scene appear flattened by the long lens, which makes the distant mountain range appear closer. Canon EOS 1100D with 70-300mm lens at 200mm, ISO 200, 1/500 second at f/11.

The second lens in a twin-lens kit is usually a telephoto zoom lens that picks up where the range of the standard zoom lens (which we looked at previously) ends and extends to cover focal lengths that are ideal for sports and wildlife photography. Like standard lenses, kit zooms are usually built to a price. However, they also tend to be compact and portable and make a versatile addition to a basic kit of camera plus standard zoom.

Lenses are generally deemed ‘telephoto zooms’ when their shortest focal length is equivalent to 70mm on a 35mm camera. This translates to a diagonal angle of view of 34 degrees and 21 minutes. Kit lenses usually extend to the equivalent of 200mm or 300mm in 35mm format.

Focal length options vary with different sensor sizes and you can often choose from two or more zoom ranges for some sensor formats. The table on the next page compares the most common tele zoom kit lenses in the main camera formats that offer twin lens kits containing a tele zoom lens.

Telephoto Zoom Characteristics

Telephoto lenses narrow the photographer’s field of view and, in doing so, make distant subjects appear closer. Nearby objects also appear to be closer in size to more distant objects of the same size because the angle of view is reduced. This is the most common application for telephoto lenses.

Telephoto lenses are often described as ‘compressing’ perspective. However, perspective depends upon where the photographer is located with respect to the subject (as outlined in the Insider in this issue). Using a telephoto lens probably means the subject is some distance from the camera ““ and that will influence perspective.

Rather than compressing perspective, tele lenses compress the sense of depth within a scene because more distant objects cover a larger percentage of the frame. In effect, objects at different distances from the camera appear to be closer together with longer lenses than with normal or wide-angle lenses. The longer the telephoto lens, the closer different objects in a scene will seem to be.

This characteristic of tele lenses can be used creatively by photographers to emphasise the number of objects in a scene or to exaggerate the appearance of congestion. However, the perceived depth compression produced by tele lenses should be used with discretion, particularly with focal lengths of 200mm or longer. Human eyes normally expect close objects to appear larger than distant ones. Very long tele lenses can make objects in a scene appear so close to each other that the scene appears static, flat and uninteresting.

Telephoto zoom lenses are popular for photographing wildlife. Taken with a 70-300-mm lens on a Canon EOS 1100D body. 264mm focal length (396mm equivalent in 35mm format), ISO200, 1/100 second at f/7.1.

Sensor format/size	Crop factor	Main focal length range	35mm equivalent	Common alternatives
‘FX’ / 36 x 24mm	1x	70-200mm	70-200mm	70-300mm
‘DX’ / ~23 x 15mm	1.5x / 1.6x	55-200mm	82.5-300mm	55-200mm, 55-300mm
M4/3 / 17.3 x 13.0mm	2x	40-150mm	80-300mm	45-150mm
‘CX’ / 13.2 x 8.8mm	2.73x	30-110mm	81-297mm	n.a.

 Telephoto Zooms for Landscape Photography

When shooting landscapes, most photographers reach for wide-angle lenses. However, telephoto lenses can produce some worthwhile results if you take advantage of the characteristics outlined above.

Whereas wide-angle lenses are often used to exaggerate the sense of depth in scenes, telephoto lenses can emphasise a sense of layering. This produces an impression of depth in a scene in a totally different way.

Scenes that lend themselves to this treatment tend to be composed of different layers at distinct and differing distances from the photographer. The closest layer might comprise nearby vegetation or a door or window frame. Beyond that there may be a hillside or the houses of a village (which in themselves may be arranged in different layers). The final layers might be ridges of hills or mountains before finally there could be the ocean and/or the sky.

Depending on the clarity of the air, you might be able to take advantage of the ‘aerial perspective’ created by diffusion. Particles of dust and/or moisture in the air can refract and reflect light, reducing overall contrast and colour saturation. A progressive loss of both characteristics will emphasise a sense of distance between near subjects and the horizon, recreating a sense of depth that may have been compromised by using a telephoto lens.

Telephoto Zooms for Portraiture

The 85mm focal length has been considered ‘ideal’ for portraiture ever since the days of film. It’s still a good portrait focal length for ‘full frame’ cameras in the digital age because it combines a natural-looking perspective with the ability to produce blurred backgrounds ““ provided the lens is ‘fast’ enough.

On cameras with APS-C sized sensors (‘DX’ cameras), a 50mm focal length will provide a similar perspective, while for M4/3 cameras the closest focal length is around 43mm. Users of Nikon 1 cameras should find the 30mm focal length provides a similar perspective for head-and-shoulders portraits.

This shot taken with a 70-300mm zoom lens on a Canon EOS 5D body shows the characteristic compression of perspective of long focal length settings and how it creates an impression of crowding in the scene. 300mm focal length, ISO100, 1/250 second at f/8.

Medium telephoto lenses ““ in this case a 105mm lens on a camera with a 35mm sensor ““ produce relatively slight compression of distance. Other cues to the depth in this scene include the layering within the scene itself and the differences in sizes between the people near the camera and those on the slope to their left.

The 85mm focal length on a 35mm camera provides a natural-looking perspective for portraits. Taken with a 55mm lens on a camera with an APS-C sized sensor the equivalent focal length for this shot was 88mm; ISO 400, 1/50 second at f/5.6.

A macro shot taken with a tele zoom lens at 120mm focal length, ISO 200, 1/160 second at f/8. Note how the background is blurred, even with a relatively small aperture. The close shooting distance required an f/8 aperture to render all of the subject in sharp focus but allowed the background subject about a metre behind it to be attractively blurred.

Some portrait photographers prefer the perspective imparted by a slightly longer lens and longer focal lengths are usually required for candid portraits. Focal lengths equivalent to 105mm and even 135mm in 35mm format are often preferable for close-up portraits that fill the frame with the subject’s face.

These lenses will also allow a greater distance between the camera and the subject, which may be more comfortable for subjects who are shy. But they will also compress the perceived distance between the subject and the background a little more than shorter lenses.

By 200mm, telephoto lenses tend to flatten faces, which may not be flattering to some subjects. In addition, there’s an increased risk of ‘choppy’ bokeh resulting from depth compression. Longer focal lengths should probably be reserved for candid portraits.

The main issue to consider when using a tele zoom for portraiture is the maximum aperture at the focal length you’re using. The widest aperture for most kit tele zoom lenses is seldom larger than f/4, and while this can deliver out-of-focus backgrounds on a ‘full frame’ camera, it may be difficult to de-focus busy backgrounds on cameras with smaller sensors.

The smaller the sensor, the greater the depth of field for the equivalent field of view and f/stop when compared with 35mm format cameras. If you can’t avoid busy backgrounds in portraits, you’ll obtain more pleasing blurring with a ‘full frame’ camera and tele lens. With ‘DX’ and M4/3 cameras, moving closer or re-positioning the subject a long way from the background may be the best (or only) solution.

Telephoto Zooms for Close-ups

The longer focal lengths of tele zooms are often used for close-ups of flowers and small insects. Indeed, some lenses have special ‘macro’ settings for this purpose. If you can’t afford a true macro lens (defined as a lens that can produce 1:1 or ‘life size’ reproduction) these lenses give you a taste of macro work without the expense of a dedicated lens.

Depth-of-focus can be an issue for close-up shooting with a tele zoom lens because the maximum aperture is usually quite small. Widest apertures of f/5.6 are common in ‘full frame’ lenses with the 200mm focal length and can be as small as f/6.7 for 300mm lenses on a M4/3 camera.

If you can’t achieve sufficient background blurring with the widest aperture at full tele zoom, try moving the subject as far from the background as possible. If this isn’t possible, change your shooting angle to ensure the background is as even in brightness and colour as you can make it.

A candid portrait of a group waiting for a ferry, taken with an 85mm focal length (equivalent to 136mm in 35mm format) on a camera with an APS-C sized sensor. ISO 200, 1/250 second at f/8.

‘Fast’ and ‘Slow’ Lenses

Terms describing the ‘speed’ of a lens have nothing to do with how quickly it can focus. Instead, the term is applied to the size of its maximum aperture. Faster lenses have larger maximum apertures than slow ones.

The main advantages of fast lenses are:

1. They let more light into the camera and this will make the viewfinder image brighter (if it’s an optical finder).

2. You can shoot with faster shutter speeds in dim lighting.

3. The plane of focus at maximum aperture is often very shallow, making it relatively easy to produce blurred backgrounds.

But they have their downsides:

1. Fast lenses require a lot more glass. This makes them larger and heavier than slower lenses.

2. They also tend to be much more expensive.

The telephoto zoom lenses in the ‘kit’ category tend to be comparatively slow, with maximum apertures of f/3.5 or smaller at their shorter ends, compared with f/2 or f/2.8 for a fast lens.

Fast lenses make it easier to blur backgrounds, particularly in close-up shots. Taken with a Canon 70-300mm kit lens on an EOS 5D II body. 105mm focal length, ISO 200, 1/160 second at f/5.

The Value of Stabilisation

Built-in stabilisation has become an important feature in many cameras and lenses and it can make a huge difference to the number of sharp images you can obtain when shooting with longer lenses. Effective systems can allow photographers to use shutter speeds several exposure values (EVs) below the recommended settings in an unstabilised camera.

Camera buyers can choose between having stabilisation built into the camera body or into each lens. Although both are almost equally effective, the advantage with moving the image sensor, instead of the lens, is that stabilisation is available with any lens you care to use ““ including wide-angle lenses.

Body-integrated stabilisation moves the image sensor to compensate for vibrations. Stabilised lenses include one or more elements that are shifted to counteract vibrations by re-directing the imaging light.

Stabilised lenses are usually larger, heavier and more expensive than unstabilised lenses because they contain more components. However some lenses provide several stabilisation settings for coping with different types of vibration, including the forwards/backwards movements associated with close focusing.

Image stabilisation is particularly useful for close-ups, when even slight camera shake can produce blurring. The stabilisation system in some IS lenses must be switched off when you mount the camera on a tripod; other lenses detect tripod mounting automatically.

 

This is an excerpt from Photo Review Issue 57.

Subscribe to Photo Review:
–  Photo Review Magazine Subscription

Lenses Guide by Margaret Brown
Lenses Guide provides all the information you need for selecting the right lenses to improve your photography.