How a Macro Lens Works

Sometimes, a photographer needs to get closer to a subject than most conventional lenses allow. In situations that call for a life-sized view of a subject, a macro lens is necessary. A macro lens is a fixed focal length lens with a reproduction ratio of 1:1 or greater. Some canon slr digital cameras with sensors that are smaller than full-frame can achieve a similar effect, while some non-macro lenses are called “macro,” but this is not true macro photography.

The term “reproduction ratio” refers to the relationship between the size of the subject on an image and its actual physical size. All lenses, whether or not they are macro, have a reproduction ratio. Thus, a 1:1 image reproduces the exact size and scale of the subject as perceived from the point where the photographer is taking a picture. Some lenses attempt to achieve a macro effect by offering 1:2 reproduction, but a lens must be able to achieve at least 1:1 magnification in order to qualify as a true macro lens. In addition, no zoom lens can ever be a true macro lens, not just because they are not primes, but because they cannot reproduce subjects at 1:1.

Macro Photography

Macro Photography

Another benefit of macro lenses is that they have greater working distance, the maximum distance between a subject and the glass of the lens at which it is possible to stay in focus, than non-macro lenses. Along with their superior sharpness, a necessity because of the amount of magnification, they are ideal for close-ups. Photographers mainly use these lenses for product photography, portraits and nature shots, especially close-ups of flowers, insects and any small objects. At such a close distance, depth of field becomes an issue, but a photographer who wishes to increase depth of field can still increase the amount of available light in order to attain the desired effect.

Macro Photography Lens

Macro Photography Lens

Some macro lenses magnify beyond the 1:1 ratio. Such lenses are useful when a photographer needs a larger reproduction ratio. In the absence of such a lens, a photographer may use extension tubes to increase the reproduction ratio and working distance. An extension tube can increase the reproduction ratio and working distance proportionally depending on the size of the tube; a 50mm extension tube on a 50mm lens effectively doubles both. It contains no glass and therefore does not affect picture quality, but, as a tradeoff, it reduces the amount of light output. It is also possible to achieve this effect with a bellows and a focusing rail. These work with all lenses, not just macros. However, these tools make automatic focusing impossible because they block the lens itself from communicating with the camera.

A macro lens has a fixed focal length and a 1:1 or greater reproduction ratio, which, along with their superior sharpness, makes them ideal for close-ups. However, not every lens that calls itself a macro lens is actually a true macro lens. While it is possible to use special tools, such as extension tubes and bellows, in macro photography, most photographers prefer to use true macro lenses for the best effect.

Berger Bros has been an industry leader in supplying the best photographers with all the best equipment. Jeremy Thorne has been involved in the marketing for the company for years and enjoys watching it thrive.









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