Camera Lenses Buyers Guide

In photography it is the lens which effectively takes the picture and the camera body that ensures correct exposure of the film. Therefore the better the performance or optics of a lens, the greater the potential quality of your pictures.

Most modern cameras have autofocus lenses, of which many can be used in manual mode as well. Autofocus allows for the lens to be automatically focused on the subject desired. This is of obvious advantage when photographing moving objects, such as in sports and wildlife photography, but is of questionable advantage in still life photography.

Autofocus does have its own limitations. Most autofocus lenses will only focus on a subject that is central in the frame. Some subjects also confuse it, like when focusing through glass. Comparing autofocus to manual focus is very much down to personal preference. Although Autofocus can be a useful facility to have, it is not essential for most subjects and it is advantageous to have the option for manual focus as well. It is worth noting that many professional cameras do not have autofocus facility. Purely manual lenses tend to be more expensive and with the advent of autofocus they have become more specialized.

Interchangeable lenses are only an option in SLR cameras and larger formats. Compacts will either have a fixed focal length lens or a zoom lens. The focal lengths given here are for 35mm cameras. For larger formats a comparative lens of the same angle of view will have a longer focal length than 35mm.

This lens is the focal length most commonly sold with a camera at time of purchase. Its focal length for 35mm photography is 50mm. The angle of view of the human eye is roughly 45 -50 degrees. This compares with the angle of view of a standard lens and is largely why this lens is so commonly used. It means that you are still relatively close to the subject, and the perspective it gives lends it to documentary style photographs whether for family or more seriously for photojournalism.

These lenses have a focal length which is shorter than that of the standard lens. For 35mm film format this is anything less than 50mm. Common focal lengths are 15mm, 20mm, 28mm and 35mm. When looking through the viewfinder the subject looks further away than it really is. The angle of view is wider and for any given aperture size they have a greater depth of field than the standard lens. The shorter the focal length, the greater the angle of view and depth of field. Angles of view obtainable roughly cover the range of 85 to 100 degrees. This lens is used for landscape photography where a wide angle of view and greater depth of field are looked for. When used for images of people it is useful in confined spaces, such as a room, and a picture of the whole scene is required. For example, with a group of people sitting at a table, a standard lens could frame just a few people, whilst a wide-angle lens will allow for more of the scene to be captured.

Long-focus lenses have a focal length, which is longer than that for a standard lens. For 35mm film format this is anything greater than 50mm. Common focal lengths are 85mm, 100mm, 135mm, 200mm and 300mm. When looking down the viewfinder they have the effect of magnifying and bringing the subject nearer. They have a reduced angle of view and for any given aperture size they have a reduced depth of field. The longer the focal length, the greater the magnification, the smaller the angle of view and the shorter the depth of field. Angles of view cover range approximately from 45 to 10 degrees. To allow for focusing, long-focus lenses must incorporate in their design a tube long enough to accommodate the long focal length and this can make some of the longer focal length lenses bulky and heavy. Telephoto lenses are long-focal lenses that are compacted in design to reduce their length and bulk, therefore making them more manageable: they are the most common form of long-focal length lenses. These lenses allow for photographs to be taken at a distance from the subject and are often used in photojournalism, travel, wildlife and sports photography. The shorter focal lengths, between 80 and 135mm, are commonly used for portraits because they give a slightly flattering affect on perspective.

Even though telephoto lenses are shorter than long-focus lenses, at longer focal lengths of 500mm and more, they can be quite bulky. To overcome this difficulty mirror lenses were developed. For these lenses, the optics are effectively 'folded up' by using curved mirrors, as well as lenses to reduce the weight and length of the overall lens. However, the finished lens is wide and as the normal aperture system is very difficult to fit in their design they have a fixed aperture of usually f8 or f11. As such the exposure is regulated, either by the shutter speed or by neutral density filters which are usually built into the lens. These lenses are also of use in photojournalism, sports and wildlife photography.

These lenses have a variable focal length. As such this means that instead of carrying a number of different lenses, you can effectively make use of just the one lens. They allow for framing and cropping of the subject without having to move in relation to the subject. They are found in a number of different ranges. The commonest is 35-70mm, 28-200mm, 80-210mm and 100-300mm. There is a price for this flexibility though and in comparison to fixed focal length lenses their optical performance is not as good. Zoom lenses are useful for travel photography when luggage weight is a consideration, and also in sports where there might not be the time to keep changing lenses.

These lenses are super-wide-angle lenses with focal lengths of 6, 8 or 10mm, giving picture angles ranging roughly from 140 to 220 degrees. At the wider angles the lens is actually seeing behind itself. This extraordinary angle appreciable distorts the image, especially on the edges, with some lenses producing a circular image. They are very expensive and have very limited and specialized use, for example giving an artistic distortion to documentary work.

These lenses are used in close up photography. Their design allows for focusing whilst at a closer distance to the subject than a normal lens, which can give greater detail to the final image. This is commonly used in wildlife photography, such as when photographing flowers, or when photographing small objects, such as coins and jewelry in archaeology. There are a number of focal lengths available, including 55mm, 105mm and 200mm. They can be used for other subjects, just as if they are a normal lens. Some zoom lenses have macro facility as well.

Usually these are wide-angle lenses, typically 28 or 35mm. Their specialty is that they have the facility to shift the lens vertically or horizontally in relation to the film. This enables the shooting of subjects, such as tall buildings, without the convergence of verticals.

These attachments can be made to increase the focal length of a lens. Fitting between the back of the lens and the camera, they effectively double the focal length of a lens. Although they can be used on all focal length lenses they tend to be commonly used on ones of longer focal length. Whilst increasing the focal length there is an associated loss of lens speed. The extended lens is of a lower optical performance than the equivalent fixed focal length lens.

Most SLR camera lenses allow for filters to be attached. This is not an option for compact cameras, although there is nothing stopping you just holding a filter directly in front of the camera lens as you take the picture. A bit clumsy but it will work. Filters allow for a whole range of effects in picture taking. Although filters effect the colour balance of light reaching the film they are still of use in black and white photography.

These are letter codes, such as FD, EF or MD, and are used for individual lenses, helping to identify the make and type of lens, whether manual or autofocus, ensuring a lens with the appropriate fitting is matched to the correct camera body. The codes are not commonly used, as the make and whether manual or autofocus will usually identify a lens.

Although there are overall guides to the use of lenses, the final choice is very much a personal preference. There are many overlaps in what lenses are used for. Wide-angle lenses tend to be used for landscapes as they give greater depth of field and picture angle. They are also used in photojournalism, often for indoor subjects where the picture needs to take in a wide angle of view. As you increase the focal length you move through to the standard lens. This lens replicates the angle of view of the human eye. Moving on to long-focal lenses, 85mm, 100mm and 135mm, in 35mm film format, are popular for portraiture. As the focal length gets longer you increase the ability of the lens to focus in on distant subjects. Thereby effectively pulling the subject closer and allowing you to keep some distance between you and the subject; this is particularly useful in sports and wildlife photography.