Donegan DA-2 OptiVISOR Headband Magnifier, 1.5X Magnification Glass Lens Plate, 20" Focal Length

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 MagnificationDiopter Magnification Focal length
(Distance from object) Sample view 20/20 vision 20″ (50.8cm) 2-diopter lens
1.50X 20″ (50.8cm) 3-diopter lens 1.75X 14″ (35.56cm) 4-diopter lens 2.00X 10″
(25.4cm) 5-diopter lens 2.50X 8″ (20.32cm) 7-diopter lens 2.75X 6″ (15.24cm)
10-diopter lens 3.50X 4″ (10.16cm) 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?OptiVISORFitted,
plastic, carrying caseInstruction manual

Features:

• Headband binocular visor with snap-in 1.5X 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
• 20" focal length for a variety of uses

Product Details:

• Brand: Donegan Optical
• Color: White
• Batteries Required?: No
• Item Weight: 8 Ounces
• Lens Material: Glass
• Is Discontinued By Manufacturer ‏ : ‎ No
• Product Dimensions ‏ : ‎ 12 x 8 x 2.3 inches; 8 Ounces
• Item model number ‏ : ‎
• Date First Available ‏ : ‎ December 17, 2004
• Manufacturer ‏ : ‎ Donegan Optical
• Best Sellers Rank: #41,096 in Health & Household (See Top 100 in Health & Household) #83 in Magnifiers
• #83 in Magnifiers
• Customer Reviews: 4.6 4.6 out of 5 stars 1,384 ratings