A high-powered zoom lens has both advantages and disadvantages.
The choice here is between a fixed focal length lens and a zoom lens. In this case, the telephoto lens has a focal length of 400 millimeters, while the zoom lens can be adjusted from a focal length of 100 millimeters to one of 400 millimeters or anywhere in between. Each lens has its own set of advantages and disadvantages.
Variable Focal Length
The zoom lens is adjustable in its focal length. This eliminates the need for changing the lens, if you want to change from a super telephoto (400 mm) to a minimal telephoto (100 mm). With a zoom lens mounted on your camera, all you need to do is change the lens adjustment. Each lens has its own specific use, so it is a great convenience to be able to switch from one focal length to another just by moving the zoom-adjustment ring.
Fewer Moving Parts
The 400 mm lens has fewer moving parts, so there is a good chance that it will last much longer and with less repairs than the zoom lens. For every time you change focal lengths with a zoom, the main lens moves in or out from the body of the camera, a condition that is made possible by a complex arrangement of camera parts.
Larger Aperture
Fixed-length lenses are usually made with a wider aperture for the lens than their zoom counterparts. For a zoom lens to have the same possible lens opening as a fixed focal length lens, the lens construction would be an expensive undertaking. With wide-angle lenses, lens apertures are not a major problem, but when using a long-length telephoto, the photographer needs every bit of available light that is possible, especially if he or she wishes to avoid mounting the camera and lens combination on a tripod.
Less Expensive
The price of a 400 mm fixed-length lens is considerably less than that for the same zoom lens. The construction of zoom lenses is a complex undertaking for the camera manufacturer, especially as the focal length increases and the lens becomes bigger and heavier.
Less Time to Focus
When using a zoom lens, a photographer can get wrapped up in trying to find the right adjustment with the focal length. Even after he or she does come up with the correct setting for that variable, there still is the focus adjustment and the calculation of the shutter speed and/or lens aperture. It is quite possible that during the time that is spent adjusting all the settings that the subject matter may have moved. Considering that high-range telephotos are often used to photograph wildlife, this is an important item to consider.
Lens Sharpness
Sometimes the images made with a fixed-position lens are sharper than those created with a zoom. The lens quality of zooms is improving, but you may have to pay top dollar to get the best quality image from a zoom lens.
Tags: zoom lens, focal length, advantages disadvantages, Each lens, fixed focal, fixed focal length