Choosing Lenses

Early amateur cameras were made with the lenses built in. These lenses were pieces of optically corrected glass that made an image on film similar to what the photographer saw. However, early-day photographers soon wanted to record images larger than they normally appeared. They knew how telescopes could bring a distant subject close up, and how microscopes could enlarge a Subject to a bigger·than·life image. Why not cameras?

Eventually cameras and lenses were
made for those purposes, and more. Today's camera stores have row upon row of supplementary lenses, and many Photographers' gadget bags have several, too. Are they all necessary?

Like auto enthusiasts who prefer an
engine with fuel injection rather than an ordinary carburetor, photographers have special preferences and reasons for using certain lenses. Many agree extra lenses can be a big help getting the results they want, while others think the camera’s basic
lens is all that is needed.

Too many amateurs buy supplementary lenses because they think the extra gear makes them look more like photographers should look Telephoto and wide-angle lenses have become common. Zoom lenses are especially popular. Macro and close-up lenses fill out the list of the "usual" extra lenses. Just what are the differences in lens types?

First, you should know that all lenses are classified by their focal length. That's the distance from the optical center of a lens focused at infinity to the point behind it where
a sharp image results. With a camera, that distance would be measured from the lens optical center to the film. The distance is measured in millimeters (mm) and is engraved on the front mount of your lens. Occasionally the focal length appears in centimeters (cm). Multiply by 10 to determine millimeters.

The millimeter of a camera lens indicates its field of view (the area it covers), and helps tell you what size image it will produce. The greater the focal length (mm), the greater the subject's image size. Currently, focal lengths range from 6mm to 2000mm. Once
you know the millimeter of a lens, you’ll know what general type of lens it is considered to be: normal telephoto, or wide-angle.

Normal lenses for camera are often 50mm or 55mm, but they can range from 38mm to 58mm.

A telephoto lens is one of longer focal length than a normal lens these generally range from 85mm up to 2000mm. Lenses of 90mm, l05mm, and 135mm are very popular telephoto types.
Simply stated, shooting from the same spot, with a telephoto lens you'll get a larger subject image than with a normal lens. The greater the millimeter, the greater the image size. For example, a l000mm lens would give an image scale 20 times greater than a 50mm lens. That's because with the longer focal length, the field of view gets smaller and the subject image appears proportionately greater.

Wide angle lenses, on the other hand, have a shorter focal length than normal lenses. Popular sizes include 35mm, 28mm, 24mm, and 21 mm. They include a greater field of view than a normal lens, and so subject image size is less with a wide-angle than a normal or telephoto lens. Some extreme wide-angle lenses including one of 6mm.
These are called fish-eye lenses because the lens surface bulges out like a fishes eye, and the field of view is similar, too. Fish-eye lenses can cover a 220° field of view, but with most the coverage is l80°. With a fish-eye lens, the camera records a subject area which appears round.

With lenses of short focal length, the exact angle of view of a specific lens may vary a degree or two, depending on its manufacturer. These measurements are made
diagonally frame.

Close-up lenses enable close focusing of a subject and a large subject image size. They usually are attached to the front of a normal, telephoto, or zoom lens. To increase the close-up magnification even more, extension tubes, or extension bellows, are inserted between the camera body and camera lens.

Macro lenses have become very popular. These allow the photographer to focus near his subject for close-ups and also make photographs at regular distances. Basically, macro lenses will do the same work as a normal, telephoto, or zoom lens that is fitted with close-up lenses, but a macro lens is easier to use and gives sharper close-up results, with some you can focus from infinity down to 2 inches. Generally, however, because of its optical design, the maximum f/stop of a macro lens is less than the maximum opening of a standard lens. For example, some macro lenses open only to f/3.5, while a normal lens may be as wide as f/1.4, a difference of 2-1/2 f/stops.

Zoom lenses first became popular with movie cameras, and then photo;
Photographers adopted them for still cameras. A zoom lens allows you to vary the focal length. That means you can increase or decrease your field of view, and the subjects image size, without moving your position or changing lenses; this makes them very convenient. And composition becomes easier, too. The range varies according to the lens. Most common are focal length which range from a minimum wide-angle lens to a minimum telephoto lens like 35-70mm, and also those of a greater telephoto range,
such as 85mm-210mm. Newer types cover extensive wide-angle to telephoto ranges such as 28mm-135mm. The major drawback of zoom lenses is that their maximum f/stop is limited, often in the f/3.5 to f/4.5 range. This means its harder to see through
the lens and focus in dim light. Some zooms have a variable maximum aperture, such as f/4-4.5; it gets smaller as you zoom to a large focal length.

Autofocus lenses are the latest lens innovation for SLR cameras. Optical sensors in the lens or camera activate a motor to automatically adjust the lens until it is in sharp focus on the subject appearing in the middle of the viewfinder. Some autofocus lenses can be used only on a specific autofocus model camera, while others have been designed for mounting on a number of the major brands of SLR cameras

Before discussing the various types of supplemental lenses more completely,here are some general facts to know. Some cameras have permanent lenses and these cannot be changed. Rangefinder cameras with between-the-lens leaf type shutters are of this kind. Close-up lenses usually can be attached to them, however.

Mounting Lenses

Mounting lenses to your camera body is accomplished by one of two methods. Cameras have either a bayonet or screw mount. Screw-mounted lenses are less expensive but less convenient. The photographer must turn the lens to screw it to the camera, and quick alignment of the grooves is not always easy. With the more common and convenient bayonet mount, the lens is aligned and inserted according to markings
on the lens and camera and a quick twist of the lens locks it in position. Some lenses with a screw base can be fitted with an adapter so they can be used on a camera
using a bayonet mount.

Many supplementary lenses can be adapted for use on a number of camera models. Some lens manufacturers design their products for interchangeable use on a variety of camera bodies. Unfortunately, there is no industry wide standardization regarding lens mounting. This is partly because camera-maker want you to buy the lenses they make especially for their cameras.
Also, automatic aperture and exposure controls vary according to the manufacturer,
and some will couple only to the lens designed for the camera

When buying an extra lens, always take your camera to the store to make certain the lens attaches properly and also makes the necessary mechanics and electrical connections to operate the aperture and display exposure information in the viewfinder.

Pricing Lenses

The cost of lenses varies considerably. Making fine optics is neither easy nor inexpensive, and much of the cost of a camera is determined by the quality of its lens. Technical ability and labor costs are price factors. Japan produces more camera lenses less expensively than any other country. Germany also manufactures lenses for cameras, and the Germans' reputation for quality optics is high. So are their prices.

Lens quality often varies according to price. Usually the more you pay for a lens, the better it is. Sometimes, however, you are also paying for the vast amount of advertising done by some lens and camera manufacturers. How precisely the glass elements within the lens are ground, polished, and mounted determine the real value of a lens. The ruggedness of the lens barrel and the durability of its mount are considerations, too. Some are easily damaged.

The major consideration regarding the quality of a lens is its sharpness. Is the picture it produces sharp corner to corner? Inexpensive lenses, especially telephoto or zoom types, tend to produce pictures with fuzzy edges. The manner in which a lens is
designed and coated to reduce flare and eliminate distortion also is important.

Another cost and value factor concerns the maximum lens opening. Generally, the wider the maximum f/stop, the greater the lens price. Maintaining sharpness with a wide f/stop is optically difficult. But photographers seem to prefer lenses with wide f/stops, such as f/1.4, to use when light levels are low. And they pay a higher price for this lens feature.

ln general, you’ll get a good quality normal lens with your camera. The decisions come when you purchase a supplemental lens. First, how much will you use the extra lens? lf your answer is often, a more expensive type is the best investment For occasional use,
a less, costly lens should be adequate. Whatever lens you purchase, if you find it does not produce sharp images,return it to the camera store for replacement.