Wildlife photography is probably the genre that is most associated with long telephoto lenses.
Rocky, in a 2023 article “Exploring The Pros And Cons Of A 400mm Lens For Wildlife Photography” made the interesting comment that “A medium telephoto lens can capture wildlife at a moderate distance as well as being a versatile weapon.” which reminds me one that choices are not normally obvious.
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Wildlife Photography with Telephoto Zoom
Possibly the most important part of your equipment is the lenses you use. It is therefore important to understand them when you make a choice to buy.
Especially if you are photographing dangerous or skittish animals the telephoto lens is critical as it allows you to keep your distance while photographing. It is anyway good to always try to be noticed as little as possible by the animal so that you don’t interfere with their normal behavior.
A telephoto lens acts like a telescope, magnifying the subject of your shot allowing you to make sure that it fills the picture so that details are visible and sharp prints can be made.
A telephoto zoom lens allows the photographer to adjust the focal length of the lens between the lens’s limits effectively allowing the shot to be framed on the spot without having to change lenses or move in or out.
Note: when this article gives focal length, it refers to the focal length on a full-frame DSLR. Because of the optics, all lenses produce more magnification on cameras with smaller sensors effectively behaving like a longer lens. The effective focal length being increased by a crop factor which for an APS-C sensor is 1.53 ie a 100 mm lens on a full frame is effectively 153 mm when used on a camera with an APS-C sensor.
The 200 to 400 zoom is a popular lens for wildlife photography being useful for larger animals from significant distances. It is also useful for groups of smaller animals further away, photographs of which are improved by the perspective of the telephoto.
Longer lenses like the 600 mm, popular with bird photographers, could be necessary for smaller animals and areas with limited access.
Teleconverters that are mounted between the telephoto and camera can multiply the focal length of a lens by up to 3 times. This is a cheap way to have access to longer telephotos but the performance and photo quality of the telephoto are reduced.
Longer lenses are available but are expensive and can get difficult to carry around. Also when a lens is used over a long distance clarity and sharpness can be lost due to haze, smoke, mist, and even heat waves.
Factors Affecting Choice
If you need really detailed information about the 400mm zoom lens, with lots of specific brand linked information have a look at Exploring The Pros And Cons Of A 400mm Lens For Wildlife Photography
Aperture and Shutter Speed
Telephotos and telephoto zooms tend to have smaller maximum apertures because of the complexity and size of the lens which also increases the costs of the lens significantly.
The maximum aperture of a standard zoom reduces with the increase in focal length. Fixed aperture lenses as the name indicates have the same maximum aperture throughout their zoom range but are very expensive.
Realize that all factors are working against each other. Choosing a longer lens reduces the biggest aperture possible which decreases the usable shutter speed which increases the need for a steady camera which is reduced by the size and weight of the lens.
Image Stabilization
With the zoom increasing the opportunity for camera shake and movement good image stabilization is a must for handheld shooting and when tracking moving subjects.
As always, you should use a tripod and remote shutter release with stabilization switched off whenever possible to ensure sharp clear images.
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Weight and Size
If you are planning to do all your shooting from a fixed position reachable by road the weight and size of the zoom are not really significant in your decision.
However, if you intend walking with your camera and shooting as you move you should definitely look smaller and lighter. One rule of thumb is that you shouldn’t buy a zoom that you wouldn’t be able to carry for the whole day.
image by Bill Larkins in Wikimedia Commons
One often doesn’t like to make compromises but here it’s definitely necessary and difficult. Maybe this is a time to borrow or rent lenses to try them out and avoid expensive mistakes. It is even possible if that big safari is a once-a-year thing, to hire rather than buy.