Aspheric lenses are a commonly preferred type of lens in both photography and eyeglasses. Their appeal stems from both a cosmetic benefit to a functional improvement over conventional lenses. They are not without their own unique problems, however, in terms of both pricing and practical use.
Definition
An aspheric lens is any lens that is not formed out of a sphere or cylinder; basically, one whose surface angle and profile are not perfectly rounded. They can achieve the same amount of refraction while being slimmer and flatter than a traditional lens, and for both photography and eyeglasses they have other significant benefits.
Photography
Without the rounded surface profile of a conventional lens, an aspheric lens in a camera helps to cut down on the distortions of certain types of lines. In addition, it prevents distortions from occurring in the wider zone of the image (i.e. where a conventional lens would be rounded). Aspheric lenses also cut out the need for several conventionally rounded lenses since it can take the place of several, making the camera less expensive, smaller and lighter.
Vision
Aesthetically, aspheric lenses provide an advantage in eyeglass wearing since they provide a slimmer profile and do not distort the shape or size of the eye. This is especially important in glasses correcting far-sightedness, since with conventional lenses the eye often becomes magnified by the excessive rounding. In addition, the aspheric lenses can accomplish this improvement without sacrificing vision quality, and, indeed, the lack of bulging curves can give even greater benefit to a wearer's peripheral vision.
Disadvantages
Unlike in cameras, aspheric lenses in eyeglasses are usually more expensive than conventional lenses since the process of making them is more refined. In addition, the slimness of the aspheric lenses means they sit closer to the face, sometimes causing visible reflections on both sides that can only be remedied by anti-reflective coating.
Development
The development of smaller aspheric lenses is accomplished through a process called molding, and these lenses are often used in point-and-shoot cameras and cell phone cameras. After the molding process, a laser (like one used to read compact discs) is refracted through the lens. Larger aspheric lenses must be ground and polished, a more difficult process and thus the reason the lenses in eye-glasses are more expensive.
Tags: aspheric lenses, aspheric lenses, conventional lenses, both photography, both photography eyeglasses, conventional lens
