- Lens quality: Are the lenses of a particular vendor known for their quality, both optically and mechanically (what is known as build quality)? Does this vendor offer multiple lens lines with economy lenses that might be a little less rugged but affordably priced, as well as pro-style lenses with the ultimate in sharpness and ruggedness? Depending on the type of photography you do, trading off a little weight and replacing a few metal parts with tough plastic might be important. Or, you might require lenses that can take punishment and still deliver sparkling results.
- Focal length ranges: Some vendors are stronger in the telephoto lens department and weaker when it comes to providing wide-angle lenses. Some do a better job with certain kinds of zooms than others. Make sure that vendor of the camera youʼre contemplating offers lenses in the focal lengths and maximum apertures you require. If not, see whether you can fill in the lenses you require from third-party vendors, such as Tamron and Sigma. These manufacturersʼ optical offerings might be completely satisfactory — or they might not. Itʼs best to see whether the lenses you will need are readily available at a price you can afford.
- Special features: Focal lengths, zoom ranges, and maximum aperture arenʼt the only features you want in a lens. You might need close focusing, fast auto focus (which is partially dependent on the design of the lens), or the ability to control the out-of-focus areas of animage. (Nikon, for example, has a line of DC lenses that are great for portraiture because youcan control how the defocused areas look.)
The lens on the camera primarily controls what viewing angle an image will be taken at. The viewing angle of a lens and the size of the image relative to that of the object is expressed by its focal length, measured in millimeters (mm) -the distance from the middle of the lens to its focal point.
Fish-Eye Lenses (6mm – 16mm) This type of lenses drastically distorts reality, by expanding the view of angle far beyond what would be considered normal for human vision. With an extreme fish-eye lens you could photograph holding your camera straightforward and still get your own feet in the picture. This type of lenses are often used for the special effect they create but can also be used to photograph interiors where there is not space enough to compose a proper image with amore regular lens.
Wide-Angle Lenses(18mm – 35mm/ focal length shorter than normal, and angle of view wider)Wide-angle lenses are probably the most common lenses around. They do expand the angle of view, but a good quality wide-angle lens can do so without distorting the image. This type of lenses also expands the perspective within the picture, which means that things that are close in distance will seem to be farther apart when seen through the camera.
Normal Lenses (40mm – 60mm / angle of view of the diagonal about 50°: a focal length approximately equal to the diagonal produces this angle) This category of lenses closely corresponds to the natural perspective of the human eye. Normal lenses are simple in construction and often produces the highest optical quality in terms of resolving power and lack of distortion. Normal lenses do not expand or contract perspective but simply see things in terms of perspective as they appear to the human eye.
Telephoto Lenses (Long Focus Lens)(75mm – < / focal length longer than normal, and angle of view narrower) When trying to capture anything further away then you can or wish to reach telephoto lenses can come in handy. By narrowing the angle of view they function just like binoculars bringing what is visually far away much closer. Telephoto lenses will also flatten the perspective within the image. When photographed with a Telephoto lens, subjects far apart in reality will seem to be much closer in distance.
Of course, the only problem with using prime lenses is that you must be willing to swap lenses whenever you decide to shoot something else or when you need a different perspective that you canʼt get by stepping closer or farther away. Digital SLRs have one additional consideration: If youʼre working in a dusty environment, you might not want to change lenses a lot because each time you take off a lens youʼre letting some dirt invade the camera body, and that dirt might end up on the sensor.
Lenses can be made to cover a single focal length or to be variable in terms of focal length.
Fixed focal length lenses
These types of lenses have the highest optical performance and they also support the largest aperture openings. The fact that the focal length cannot be varied can be to a disadvantage but some photographers claim when continuously using a single focal length lens you eventually learn to see and compose your images after that given perspective so that when you lift the camera you have already positioned yourself in the right place at the right moment to take the picture you intend.
These types of lenses can be very convenient to use since they can cover a large degree of focal lengths within the same lens and therefore minimizing the need for additional lenses. Most common zoom lenses cover a focal length from a wide angle to a telephoto, typically35mm – 75mm. Constructing a zoom lens is far more complicated than constructing a lens with a single fixed focal length. Because of this zoom lenses are often of a lower optical quality than fixed focal length lenses, they can also be considerably more expensive. Another drawback with zoom lenses is that they canʼt support as wide aperture openings as fixed focal length lenses can.
Stay tuned next week for more on camera lenses.
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