JOHN HARRIS, EXPLORA:
What defines an ultra-telephoto lens? Of course, it’s the “ultra” (or at times “super”) prefix that we are concerned with when talking about these lenses, which enable photographers to get a close-up view of something from which we normally remain very distant.
These lenses are used primarily for photographing wildlife, sports, journalism, and perhaps paparazzi or “stake-out” photography. If most readers are not going on a stake-out or stalking stars, let’s say a clear majority of ultra-telephoto lens users are photographing sporting events, airplanes, boats, birds, or wild animals.
Let’s discuss some of the notable versions of these lenses, which are considered to begin at the 400mm focal length (or that equivalent when using crop-sensor camera systems) and top out at 800mm. Canon, at one point, did sell a 1200mm f/5.6 EF-mount lens, which we were lucky enough to try.
Read more, here.