The portrait lens

Although almost any lens can be used to take portraits of people, some are more effective and easier to use than others. Wide angle lenses are not a good choice, but they require you to work very close to your subject in order to fill the frame with just head and shoulders. The close viewpoint results in perspective distortion and makes the subject feel uncomfortable besides.

So called normal lenses allow for better perspective than wide angles, but they still call for too close a viewpoint. On the other hand, very long focal length lenses magnify the image too much and have to be used so far from the subject that indoor portraiture becomes impractical.

The best size portrait lens for any camera is one with a focal length of 1.5 to 2 times normal. In the 35mm camera filed this covers focal lengths from about 80mm to 105mm. Such a lens allows you to position your camera at a comfortable distance, providing good perspective while still filling the frame with a close up view.

If wire sharp images of the proper size are satisfactory for your purpose, then an ordinary lens of about double the normal focal length will serve you well. However, if in addition you desire portraits that possess an alluring softness – a glowing quality that subdues wrinkles and other defects while enhancing the subject – you will need a special purpose optic known as a portrait lens.

Times ago, even the best lenses obtainable were burdened with so many aberrations (defects) that really sharp images were impossible to achieve. This was a drawback for many kinds of photography, but not for portraits.

Over the years, as aberrations were tamed and image quality improved, lenses lost their characteristic flattering softness of earlier times. But since it was a defect known as spherical aberration that had caused the glowing fuzziness admired by so many portrait photographers, lens deliberately retained this one. The result was lenses that offered a whole range of soft focus effects, depending upon how far they were stopped down. (Spherical aberration is caused by the light rays which enter around the edges of a lens, coming to a focus at a different point from those entering through the center. Therefore, a portrait lens is softest at its widest aperture, but gets sharper gradually as it is stopped down. At f/8 or so and beyond the resolution is equal to that or any ordinary lens.)

Early portrait lenses were designed for use on large studio cameras only. Now these special purpose optics are also available for all DSLR cameras. Today the choice of f-stops is not the only means of controlling the degree of softness. Movable internal lens components, filters that block out parts of the light beam, or metal inserts that look like sink strainers also help to regulate the amount of diffusion.

You should understand that soft focus is not the same as out of focus. A sharp lens thrown out of focus renders everything mushy and unsatisfactory but a carefully focused portrait lens delivers an image in which every part of the subject is both in and out of focus at the same time. The effect is charming and romantic.

Keep in mind the fact that a portrait lens, while it is ideal for its intended purpose, needn’t be confined to pictures of people. Landscapes and many other subjects can also benefit from the velvety softness. The possibilities inherent in this versatile optics are limited only by a photographer’s imagination.


More about Special Purpose lenses

- Portraits Lens
- Tips on using Portraits Lens


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