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Donegan DA-4 OptiVISOR Headband Magnifier, 2X Magnification Glass Lens Plate, 10" Focal Length

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ASIN B0015IS6K2

Product Specifications
Part Number
DA-4
Number of Items
1
EAN
0633096000496
Item Size
10.5 x 8.1 x 2.2 inches
Size Name
2x Magnification, 10" Focal Length
Style Name
4 Diopter; DA-04
UPC
633096000496
Specification for this product family (See all  products)
UNSPSC Code
41100000
Brand Name
Donegan Optical

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Key Features

  • Headband binocular visor with snap-in 2X magnifying lens plate for hands-free viewing
  • Ground and polished glass prismatic lens for improved focus and reduced eye strain
  • Visor size-adjustment knob for customized fit
  • Visor tilts out of way when not needed
  • 10" focal length for a variety of uses

Package Details

Shipping Weight: 0.4 pounds
Package Size: 10.3 x 8.1 x 2.1 inches

Product Description

The Donegan OptiVISOR is a hands-free, headband binocular magnifier that has optical glass lenses that are ground and polished into prismatic lenses for quality and clarity, and is available in multiple dioptric strengths (indicated by the number in the model) which provide specific magnification power (X) at specific focal lengths, or distance from object. This magnifier enhances the size and resolution of an object or image, and is commonly used for a variety of applications such as jewelry-making, watch- making, needlework, artwork, electronic inspection, book-reading, print inspection, and stamp-collecting.

The OptiVISOR magnifier features replaceable binocular lenses that have beveled edges that are mounted in an interchangeable plastic frame. An adjustable headband with padded leather comfort band conforms to a variety of head sizes and provides comfort for hours of continuous use. It can be worn over prescription or safety eyeglasses. A durable, plastic visor tips up above the forehead when not in use. Spring-loaded pivot screws hold the headband in a raised or a forward-facing position. The magnifier weighs 0.67 lbs., and comes housed in a protective shell and carrying case. It has a one-year limited warranty.

Diopter (D) is a technical term for the measurement of the light curvature and thickness of a lens. A dioptric number and a magnification number are not the same thing. Diopter strength represents a specific magnification power (X). For example, a 5-diopter provides 2.5X magnification (at a distance of 8”). See the magnification chart. The higher the diopter, the more magnification a lens can provide. As magnification increases, distance to the object (focal length), and field of view (diameter, or narrowness of view) decreases. Magnifiers and prescription eyeglasses have a diopter value, such as 1.5 or 2. The dioptric strength of an accessory lens, such as prescription eyeglasses or an eye loupe, must be added to the dioptric strength of the magnifier to calculate total magnification.

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, reading, print inspection, and stamp-collecting.

 

Determining Magnification

Diopter
Magnification
Focal length
(Distance from object)
Sample view
20/20 vision
20" (50.8cm)
No Magnification
2-diopter lens
1.50X
20" (50.8cm)
1.50x Magnification
3-diopter lens
1.75X
14" (35.56cm)
1.75x Magnification
4-diopter lens
2.00X
10" (25.4cm)
2.0x Magnification
5-diopter lens
2.50X
8" (20.32cm)
2.50x Magnification
7-diopter lens
2.75X
6" (15.24cm)
2.75x Magnification
10-diopter lens
3.50X
4" (10.16cm)
3.50x Magnification

Donegan Optical manufactures and distributes precision visual devices for hobbyists and professionals in industry, home, office and crafts applications. The company was founded in 1952 and is headquartered in Lenexa, Kansas.

What’s in the Box?

  • OptiVISOR
  • Fitted, plastic, carrying case
  • Instruction manual

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