Donegan V388-1 Vantage Series Linen Tester Magnifier with Lens, 5x Magnification, 1" Focal Length

The Donegan V388-1 Vantage Series linen tester is a double lens magnifier with a scale in inches along two edges of the base, for use in textiles, graphic arts, engraving, and industrial inspection. It has 5x magnification and a 1" lens. The frame is 2" high and folds flat for storage. The frame is constructed of black-enameled brass for visibility and durability.

Magnifiers are devices used to enlarge the visual appearance of an object or image. Magnifiers come in a variety of styles such as hand-held, headband, standing, clip-on, eye loupe, and those that hang in a necklace form, or fit in a trouser pocket. Magnifiers are commonly made of plastic or glass. They can have one or more lenses with varying magnification abilities, and can have a binocular configuration with a single lens, or two separate lenses. They are sometimes used with LED or fluorescent light sources to help control viewing capabilities. Magnifier ability is often expressed as magnification at a specific length. For example, 1.75X at 14” means that when a magnifier is held at 14” from a viewer’s eyes, the object will be magnified 1.75 times (X) its actual size. As magnification increases, viewing areas and focal length decrease. Magnifiers sometimes have a diopter number, expressed as + or -D, which is a measurement of strength (or power) of the lens. Some magnifiers are marked with a dioptric number on the lens. A high diopter number has a higher magnification than a low diopter number. Aspheric magnifiers, unlike spheric magnifiers, produce a sharp image to the edge of the lens for less distortion. Magnifiers are widely used in jewelry inspection and fabrication, watch-making, needlework, artwork, fly-tying, electrical inspection, reading, print inspection, and stamp-collecting.

Donegan Optical manufactures precision visual devices such as magnifiers and optical loupes. The company, founded in 1952, is headquartered in Lenexa, KS.