The thought behind selecting a Canon telephoto lens is, you have or you would like to own a Canon camera with interchangeable lenses, each which has its own specific capabilities. People who are not really into photography would be inclined to stay away from cameras that require changeable zoom lenses, implying basic point and shoot cameras that are outfitted with fixed lens and what many people are wanting simply because of their ease of use.
Canon has really stepped up to the plate by making things real simple for you, Canon telephoto lens can typically be sorted into 3 classes, they are sorted according to how big of a visual field they can get into a picture and how much detail they can take in, and the visual field they capture of each of the lens is specified mathematically by an optical physic attribute called focal length of the lens.
A good example would be...Let's suppose you would like to refer to a lens as [normal], this implies it essentially must be able to capture the view that a normal human eye can see. Talking in technological words a [normal] lens has a focal length of 50mm [if your camera is among the Canon EOS models, SLRs, or Cameras that take images utilizing 35mm film].
Now, just like what you see, [normal lenses] are only beneficial if you are only taking pictures in a convention close up range, NOT good for zooming up to get more details, NOT good as well if you want to take a photo of something far away, and so, normal 50mm lenses are fine if your are shooting a waist-up picture of someone in an ordinary room. For a more detailed picture or shots in the distant you need more [powerful lenses].
Let's use the example of taking a photograph with a group of acquaintances at a Christmas party, in this situation you want get everyone into the picture, and for this function a wide angle lens is consequently appropriate, unless of course you can get higher or move back far enough to put everyone into view ,which means you'll have to stand too far away. On a Camera that takes photos in 35mm film, a wide angle lens would have a focal distance of 35mm or less.
On the opposite end of the spectrum is the Canon EF 75-300mm Telephoto Zoom Lens, the idea of this lens is like using a telescope, which means you can place a chosen scene into focus and get more details from that scene. The end result of photo taken is, the person or a landscape your focusing on appears nearer than it actually is, and the finer details can be seen. Telephoto lenses have a focal distance up to70mm more than a regular 35mm film camera.
The classes and description given in this article are merely a rough overview and short introduction to get you familiar with the Canon Camera Lenses. The decision of which Canon zoom lenses to buy will depend on the types of pictures you want to take and your experience.
Amazon sells them for $138.00 or you can get a used one for $108.00. I seen it advertised at TigerDirect for $199.00 and Walmart had it for $149.00.