In my earlier post, here, I discussed getting in close increases the impact of Zoo photography by eliminating unnatural elements of the exhibit and creating a detailed intimate image of the animals. Getting in close requires a telephoto zoom lens, below I discuss what focal length lens you should purchase.
The zoom lens you choose should have a maximum effective focal length between 300mm and 500mm. Note that I stated “effective” focal length. When you buy a zoom lens it’s focal length is stated relative to a full frame camera. For example if I were to purchase the popular 70mm – 300mm canon zoom lens and placed it on my full frame Canon 5d Mk III body it would be exactly a 70mm – 300mm lens as stated. However if I placed it on a “crop” sensor camera such as a Canon Rebel or Canon 7d then I have to multiply by the crop factor of 1.6 then the zoom lens has an effective focal length range of 112mm – 480mm! If you placed the same focal length range on a Nikon crop camera such as a d7100 or d3100 you would multiply by a 1.5 crop factor for an effective focal length range of 105mm – 450mm.
Now that you know how to calculate the focal length range of a lens on your type of camera body you can look for the many Canon and Nikon telephoto zooms that have at least a 300mm maximum focal length. You should also investigate the third party lens makers Tamron and Sigma which make lenses for Canon, Nikon, and other cameras.
With a telephoto lens allowing you to get close to the animals next we are going to start exploring how to use your camera and lens to take better Zoo photographs.