• The advantage of the telephoto is to isolate far away detail in an image, give a narrower view than the normal lens. Their focal lengths are long and their angles of view are narrow.
• They come in different focal lengths, with the longest very expensive ones approaching the ability of telescopes to magnify images. Image magnification is not the sole purpose of telephoto lenses. Their inherent shallow depth of field makes them useful in eliminating unwanted foreground and background objects by simply throwing them out of focus. Also, their foreshortening characteristic can make portraits look much more pleasant and natural, and can visually compress distant objects so they don’t look so far away. The full moon, for instance, can seem so much larger and closer when photographed through a telephoto lens.
• Telephoto lens between 80 and 135mm is most appropriate for shooting portraits the 105 mm is considered to be the classic portrait lens. Those between 135 and 300 can be used for sports and nature photography while the super telephoto lenses, those over 300mm, are often used to capture sports and wildlife. The larger the lens the closer you can get to distant objects but the trade off is greatly increased cost, size, and weight. Increasing weight also increase the need of a tripod or higher shutter speeds to prevent camera shake.
• The 180 mm to 200 mm lens is ideal for sports when the action is taking place just in front of you and even a 200 mm lens can be easily hand-held when shutter speeds exceed 1/200 second. If you are way off in the bleachers, you’ll need a more-powerful lens. Lenses in this range are also good lenses for news photography. The speed of the lens is critical at this focal length. My favourite telephoto is a Canon 70-200 , 2.8 zoom, it can be double with Canon extender x2.
|Canon 5D Markiii, 800mm, f11, 1/1250sec ISO 640, too soft|
|Canon T4, 800mm x 1.6 1280mm f11, 1/2500sec ISO 800, too soft|
• A 300 mm lens does everything a 200 mm lens will do, except it brings subjects even closer. The problem with lenses in this size is that the best ones - those that are fastest - are quite expensive. I question the merits of buying a 300 mm lens for action photography when its maximum aperture is ƒ/5.6 or even ƒ/4, because the shutter speeds required are often so slow that you sometimes can’t capture fast-moving images without subject blur. But, a 300 mm lens that has a very wide ƒ/2.8 maximum aperture is quite costly around $7000 US. Of course, not only cost is a factor with larger faster telephoto, the weight too, it's very hard to hand-held, you need to use a tripod or at least a monopod.
• I am using 2 telephotos the first one a Canon 70-200 f2.8 IS USM, one of Canon best lens, and now that Canon launch the 70-200 f2.8 IS ii USM, you can get the older version for a lot less money and frankly I don't see any reason to pay $1000 more for the newer version, if you have the money to spend hey go ahead. This telephoto mounted on a full body with a Extender 2x will up the range to 140-400 f5.6, the image quality can suffer a bit when using an extender but not that much, and auto focus work fine, if you put the same arrangement on a 1.6 crop body like canon 7D that will give you a range of 224-640mm, Canon Extender are not cheap but compare to the cost of super telephoto it's quite affordable.
• The second telephoto that I am using is Canon 100-400 4.5, 5.6 another great Canon lens, great range even on a full body, it become a 200-800 f9 to f11, with a Canon Extender x2, at f11 auto focus is almost impossible, mounted on my 5D mark iii, it will focus at the longer range "800mm f11"only by using the life view and AF On button, it's ok if you have a fix subject and time, it's faster to focus manually. The range on a 1.6 crop body "320-1280mm". When I go out with this telephoto I normally don't bring my Canon Extender I find the image too soft as you can see on my test, I bring my kenko teleplus Pro 300 1.4 extender, with this extender my range goes to 140-560 f8, at f8 I get a fast auto focus from the view finder, great for wildlife, I always bring a strong heavy tripod, this telephoto is very heavy and difficult to hand held, the extended barrel make it front heavy especially with the Canon Extender x2, as you can see in my first image. I tested this lens at full range with both the full and crop 1.6 body & Canon Extender x2, shooting from my living room window, during lunch not the best light, both shots were done with auto focus, very slow focusing for both camera, and only possible on live view, result is very soft image. I will not suggest to used this arrangement often, but if you need the range, it will work, if you have the money buy a super telephoto or rent one.
|Canon 5D Markii, 100-400 at 400mm, hand held, f5.6, 1/400, ISO 200, for this shot I had I couldn't use a tripod, I was almost running after him, no time only action, at 1/400 I was able to get the shot without blur, a lucky day!|