Auxiliary Lens

Auxiliary Lens


(or lens attachment), a lens attached to an objective to change its focal length. A positive lens decreases the focal length, and a negative lens increases it. Positive lenses are used for large-scale photography (macrophotography) with still and motion-picture cameras, in which extension of the lens toward the object being photographed is limited. The focal length f’c of the optical system consisting of the objective and the auxiliary lens is determined from the formula

where f’Obj and faux are the focal lengths of the objective and the auxiliary lens, respectively, and d is the distance between the second principal plane of the auxiliary lens and the first principal plane of the objective lens.

An auxiliary lens reduces the image quality because of increased aberrations. Reduction of the objective’s aperture (stopping down) and the use of yellow or yellow-green light filters to reduce the chromatic aberration effect are recommended to reduce the effects of the auxiliary lens on image quality.


References in periodicals archive ?
However, with some designs the patient's spectacle correction may be glazed into a small auxiliary lens unit that may then be clipped directly over the telescope's eyepiece lens (see Figure 4).
This is the way the Bucky-Einstein cameraworks: Light from the scene or object being photographed comes into an auxiliary lens and falls on the photoelectric cell.
5X auxiliary lens fits over the standard lens increasing magnification to 3.
Removing the auxiliary lens changes the range of magnification to 84X-540X for inspection and fine geometry probing.
The flat, low-profile package of the QSB34GR makes it suitable for use with an auxiliary lens for focused image sensing.
25x, while magnification can be increased or reduced with the addition of an auxiliary lens.
TESAVISIO measuring machines offer 20 X to 135 X standard magnification with 40 X to 270 X available with an optional 2 X auxiliary lens.

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