Choosing a lens

What to know about selecting a suitable focal length

Atelephoto or super-telephoto has a couple of key benefits when it comes to wildlife photography. Often you just can’t get close for a frame-filling shot with a short lens – either because the animal will just clear off or you can’t physically get any nearer. The narrow angle of view afforded by a long focal length also makes it easier to pick out an uncluttered area of the backdrop and throw the foreground and background out of focus with a wide aperture, such as f/4.

For wildlife photography you’ll be looking at 300mm as a minimum, with 400-500mm being preferable – and you’ll still need to be surprisingly close to get a frame-filling shot. Super-telephotos in the 600-800mm category are cumbersome, and best reserved for the likes of bird photography where you typically never have enough reach. Adding a teleconverter to the lens can help in this regard. For instance, a 1.4x extender increases the effective focal length by x1.4, while a 2x extender effectively doubles the focal length. This comes at a price: light. A 1.4x extender reduces the effective maximum aperture by one stop, while a 2x extender reduces it by two stops. So, with a 2x teleconverter, a 500mm f/4 lens effectively becomes a 1000mm f/8 lens.

The crop factor of the APS-C sensors found in the majority of Canon cameras can be a benefit when it comes to shooting wildlife. These sensors are 1.6x smaller than a full-frame sensor, which means they appear to give more ‘reach’. The trade-off is that smaller sensors don’t produce the same image quality at the high ISOS you might need when photographing animals towards dawn and dusk.