Some lenses have one purpose, while others cover several ranges, for example a kit-lens, a lens you often get when buying an entry level dslr, can go from some wide-Angle focal ranges to standard focal range, telephoto range and also with some limited macro capability also.
This is actually what is known as a 'zoom lens', and they often cover a focal range of 28mm all the way through to 80mm or more. This covers three focal ranges known as:
A zoom lens, is also a sub-category lens, as it covers the various focal ranges.Macro-lenses (50/60/105mm)
Brackets-key: Any lens covering the entire mm focal range, or some of it. ex. 20 – 28 mm is also a wide angle lens.
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lens reviews of the basic types, what they do and possible uses
Lens Reviews – Wide-Angle Lenses
A wide angle lens can take in a wider angle of view than a standard lens, and on infinity, can maintain a good depth of field, as in, more things are able to be kept in focus no matter near, in the mid-ground, or background. A wide angle lens is any lens that goes from 6 to 28 mm.
Wide-Angle Lenses – Possible Uses
Wide-angle lenses are most commonly used in landscape photography of one description or another. But they can also be used in many other types of photography too, take a look at the great shot of a London bus above as an example.
Wide-angle lenses are also used when using digital photography to take pictures of some forms of architecture.
Another common use is any type of photography done in low-level light, as a wide angle lens can allow the photographer to still keep a small aperture as it allows more light in compared to a standard lens or telephoto lens.
For more about digital landscape photography click here:
Digital Landscape Photography
Lens Reviews – Standard Lenses
A standard lens is a lens with a focal length of 35 – 50mm. This type of lens gets the best 'true' image of a subject 'as the eye' sees it.
Many years ago most slr's used to come with a standard lens, as opposed to a lens that covers a range of focal lengths (zoom lens), as they mostly do these days.
A standard lens has great optical quality, and a fast wide aperture (f1.8) which is really useful in low level light.
A standard lens doesn't distort an image the way a wide-Angle lens might, or alter the perspective like a telephoto lens can. It sees what your eye sees... or at least what the human eye has in focus, peripheral vision excluded.
Standard Lenses – Possible Uses
A standard lens is great in still-life photography, landscape photography and also portrait photography, depending on your style of portraiture, that is.
This natural perspective lens, can make natural scenes appear more real.
Lens Reviews – Telephoto Lenses
The main point of a telephoto lens is to make a distant object appear close, and also to enable the photographer to greatly control the composition of a photograph by using the extensive focal length. From focal ranges of 80mm to 500, telephoto lenses can come in very useful.
Telephoto Lenses – Possible Uses
Telephoto lenses are often used in sports photography, where the photographer either doesn't have the luxury of being up close (football), or wouldn't want to be up close (Formula 1).
Telephoto lenses are also used in wildlife photography so as not to disturb the animal and its natural interaction with its environment, although you are probably looking at focal ranges around 300 – 500mm.
Another common but surprising use is in portrait photography. Many portrait photographers actually only use a telephoto lens in their portraiture. Finding that the control over frame composition and the flattening effect on the background is appealing.
Lens Reviews – Macro Lens
A macro lens allows you to take photos of something very close and have that subject magnified and still in focus, and/or larger than life.
So, taking a photograph of a pin-head for example, and making it appear 'larger than life' in the final image...
...Or at the very least the same size, is what is generally called macro photography these days.
Macro Lenses – Possible Uses
Any photographs you want to take of a subject for very close detail are what you would use a macro lens for.
Things such as flowers, insects and textures; subjects that the human eye usually doesn't notice, always make for great shots. Also often used in some kinds of technical photography.
What focal range the macro lens has is also quite important.
A macro lens with a focal length of 105mm, would allow you more distance from the subject, Important when shooting insects or anything that gets spooked easily.
This also positively effects the light, whereas being close as you may be with a 50mm macro lens, may cast a shadow.
For more about how to use a macro lens click here:
Macro Digital Photography
Which Lens Should I Buy?
At some point most photographers buy one of the above types of lenses after reading some lens reviews.
There is no exact lens you must have.
It simply depends on what you will use it for, and also, your budget.
The most well known and respected brands of lenses are: