To new photographers it can be quite surprising just how many types of lenses there are. Understanding the options is the first step to building your own photo system.

There are three types of lenses

• Normal : Focal length of 50mm
• Wide : Focal length of 28mm and lesser
• Telephoto : Focal length of 90mm and more

These lenses are further classified according to the aperture each of these lenses provide and some special features. Nowadays most of the lenses come with so many features which differentiates one lens from the other. Among these features most notable is the Image stabilization feature. There is a different set of lenses called Prime lens, these set of lenses have fixed focal length.Aperture and focal length

The two main optical parameters of a photographic lens are the maximum aperture and the focal length. The focal length determines the angle of view, and the size of the image relative to that of the object, while the maximum aperture limits the brightness of the image and the fastest shutter speed usable.

The maximum usable aperture of a lens is usually specified as the focal ratio or f-number, which is equal to the focal length divided by the effective aperture (or entrance pupil) diameter in the same units. The lower the number, the more light per unit area is delivered to the focal plane. Larger apertures (smaller f-numbers) provide a much shallower depth of field than smaller apertures. Focal lengths are usually specified in millimeters (mm). More the focal length of your lens the more you can zoom into the picture or more closer you can get near the picture.

Types of LENS

Standard Lenses (~50mm) : A standard lens is the usual lens supplied with an SLR. They are good general purpose lenses having an angle of view close to the human eye. They are sharp, compact and lightweight. Small “standard” zooms have a range of typically 35-70mm (2x), 28-85mm (3x) or 24-105mm (4x). These zooms often replace the 50mm lens. A typical compact has a zoom lens with a focal range of 35-100mm.

Wideangle Lenses (<50mm) The natural choice for landscapes, sweeping panoramas and other outdoor scenes, group shots and generally anything requiring strong perspective. In some situations a wideangle might be the only way to capture the entire scene without excluding an important element in the frame. A characteristic of wideangle lenses is a deep depth of field making constant refocusing less critical. Good when you’re in a hurry or the subject is moving fast such as photojournalism.

Medium Telephoto Lenses (85-135mm) These lenses are perfect for portraits. Compared to a 50mm lens they isolate the subject from the background more and the increased focal length slightly flattens the image and gives more a natural and flattering perspective. Popular for candid photography.

Long Telephoto Lenses (>135mm) Used for sports, nature or other types of documentary style photography that requires you to be close to the action but cannot be close physically be it dangerous or timid. Like portrait lenses they are great for picking out the subject from the background.

Other Special Lenses

Macro Macro lenses can focus very close allowing real size, 1:1 image ratios, ie an object 10mm in size will appear 10mm on the 35mm frame. Excellent for nice close ups of insects or flowers.

Fisheye Lenses Distort the perspective to create a circular “fisheye” 180° image. A very specialised lens. Picking the correct subject is necessary but when you do can produce some memorable images. Focal lengths vary, 7~16mm.

Super Wideangle Lenses (<24mm) Like wideangle but more so, but not as much as the fisheye. Great for exaggerated perspective or scenes from restricted vantage point. Favoured lens of the estate agent!

Super Telephoto Lenses (>300mm) Longer telephotos and an eye-watering price tag to match. Can be heavy due to the amount of glass they contain. Often they have a tripod mount on the lens. You will need to tripod mount to reduce camera shake and weight of lens (unless you’re after a work out!) Favoured by tabloid journalist when spying on celebrities!

ZOOM LENSES vs. PRIME LENSES

A zoom lens is one where the photographer can vary the focal length within a pre-defined range, whereas this cannot be changed with a “prime” or fixed focal length lens. The primary advantage of a zoom lens is that it is easier to achieve a variety of compositions or perspectives (since lens changes are not necessary). This advantage is often critical for dynamic subject matter, such as in photojournalism and children’s photography.

Keep in mind that using a zoom lens does necessarily mean that one no longer has to change their position; zooms just increase flexibility. In the example below, the original position is shown along with two alternatives using a zoom lens. If a prime lens were used, then a change of composition would not have been possible without cropping the image (if a tighter composition were desirable). Similar to the example in the previous section, the change of perspective was achieved by zooming out and getting closer to the subject. Alternatively, to achieve the opposite perspective effect, one could have zoomed in and gotten further from the subject.

The primary advantages of prime lenses are in cost, weight and speed. An inexpensive prime lens can generally provide as good (or better) image quality as a high-end zoom lens. Additionally, if only a small fraction of the focal length range is necessary for a zoom lens, then a prime lens with a similar focal length will be significantly smaller and lighter. Finally, the best prime lenses almost always offer better light-gathering ability (larger maximum aperture) than the fastest zoom lenses– often critical for low-light sports/theater photography, and when a shallow depth of field is necessary.

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