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A zoom lens offers a continuously variable focal length, normally without the need to refocus. A wide-angle zoom covers a range of focal lengths that include a wide angle setting. A standard zoom goes from a slight wide angle to telephoto and a telezoom covers a range of telephoto focal lengths. Some zoom lenses are called super zooms because they cover a larger range of focal lengths from wide angle to longer telephoto.
This is the eye of the camera and is used to capture the image it sees onto the camera's light sensitive film, or CCD in digital camera. The size of lens is measured and indicated as a focal length. Cameras come with either a fixed lens or zoom lens with a range of focal lengths (see lens range) and on some SLR and rangefinder cameras the lens detaches so others can be attached to increase versatility. With a detachable lens camera it's often possible to buy just the body with a lens of your choice.The amount of light passing through the lens is controlled by an aperture, which is often quoted with its maximum aperture setting.Buying adviceSLRs: If you intend buying a specific lens in the future make sure that it's available in the same mount as the camera you are considering or own. Also if you're upgrading cameras, buy one with the same lens fitting or one that can be adapted to save the cost of replacing all the lenses you own.Digital and compact cameras: A fixed lens camera can often be much smaller so could be selected if you need to travel light. It's also less expensive if your budget is tight. It's better, though, to choose a camera with a zoom if you can afford to, rather than using a digital zoom or cropping the picture later. Go for one with a wider angle zoom if most of your pictures will be landscapes, interiors or family group shots.Choose a version with a longer telephoto setting if you want to shoot long distance subjects, portraits and wildlife.
(Not be confused with Fixed focus lens!) A lens that only has one focal length (as opposed to a zoom lens). A fixed focal length lens (also called 'prime lens') will often have good brightness, contrast, and be optically well-corrected. For that, it doesn't need any special glass or aspheric lens elements. Fixed focal length lenses are always superior to zoom lenses if they're made with the same optical materials and standards. They usually offer a wider maximum aperture than zoom lenses. They're often preferable for indoor shooting, but are also favourite choices as long telephoto lenses used for wildlife, sports and news photography.
Cameras with figures in this column have a digital zoom that increases the magnification of the optical lens by the quoted figure. To do this it uses part of the CCD so the resolution is reduced to allow for the increase magnification. If you dont intend making big enlargements this is useful other wise stick to the optical zoom. Most cameras have the option to turn the digital zoom on or off.
An electronic flashgun feature that allows the flash coverage to be adjusted. Flashguns are usually designed to cover the same angle as a standard lens, so when a wide angle lens is used you may find the edges of the frame are darker. A zoom head pulls closer to the flashtube to widen the angle and extends to throw the flash light out at a more concentrated angle.
Cameras with zoom lenses have either a rocker control, two buttons or a lever to adjust through the focal lengths of the lens. You can adjust this while looking through the viewfinder and then let go when the desired angle of view is reached.
Extreme wide-angle lens that gives 180 degrees coverage and is uncorrected for curvilinear distortion so you produce a heavily distorted photograph. If the photo turns out to be rectangular or circular, and how distorted it looks, depends on the lens and the camera. There are basically two kinds of fish-eye lenses for photography: 1. Lenses that produce a circular image, typically 8 or 10mm lenses, used on 35mm cameras or full-frame digital cameras. They produce a circular image with dark corners (due to most photos being rectangular). A similar lens is available for digital cameras with a so-called "cropped sensor". To achieve the same circular effect, it's a 4.5mm lens. 2. Lenses that produce a rectangular image. These lenses enlarge the image to cover the whole rectangular frame of a photograph. They are typically 15 or 16mm lenses. On a 35mm or digital full-frame camera they produce rectangular but still heavily distorted images without dark corners. The same lenses on a digital camera with a cropped sensor will still have a distorting effect, but less so. Fish-eye lenses used to be prime lenses only, but one company has gone so far as to produce a 10-17mm fish-eye zoom lens. This lens still produces distorted, curvy images, but zooming in lessens the distortion.
A lens that can be adjusted from one focal length to another. Wide zooms cover a range of wide-angle focal lengths while tele zooms cover telephoto ranges and superzooms go from wide angle to a long telephoto.
Called 'extender', 'lens extender' or 'telephoto extender' by some manufacturers. (Not to be confused with an 'extension tube'!). A teleconverter is an accessory that fits between the camera lens and body to increase the focal length of a lens by 1.4x, 1.7x, 2x or 3x. When coupled with a 200mm lens, for instance, teleconverters would give these results: a 1.4x teleconverter gives an effective focal length of 280mm, while a 1.7x teleconverter increases this to 340mm, a 2x teleconverter to 400mm and a 3x to no less than 600mm. Teleconverters are compatible only with selected lenses, so always check with the manufacturer or retailer before buying. Although they will work with some zoom lenses, they're best used with (fast) prime lenses, since there usually is a drop in quality, and many prime lenses give a higher level of quality to start with. Besides changing the effective focal length, the effective aperture of the attached lens is increased by one or more stops as well. Autofocusing usually does not operate if the effective maximum aperture is greater than f/5.6 with the lenses/cameras from most manufacturers (in some cases greater than f/8, like on the Canon EOS 1V and EOS 3 cameras). And not all teleconverters support autofocus in the first place!
This is the widest aperture that can be selected on the camera and is an indication of the speed of the lens. On zoom lenses two figures are often given. One is for the lens at the wide-angle setting and the other is for the telephoto setting.
CIPA test camera batteries to make it easy to compare their expected life. There is a standard measuring procedure for high power-consuming functions such as colour image display activation, use of flash, zoom and retractable lens movement. It doesn't include audio and movie recording functions.