Jeweler's Optical & Inspection Gateway
Gateway to magnifiers, jeweler's loupes, microscopes, headband magnifiers, lamp magnifiers refractometers, etc.

 

HOW TO SELECT MAGNIFIERS

Precision work routinely requires magnification to increase the visual size of objects. As the eye comes closer to an object, the apparent size and detail is increased. However, the ability of the eye to focus correctly diminishes at distances closer than 10" (254 mm). Use of a magnifier provides increased focusing power, resulting in the visual effect of a clearer, larger image of the object.

FOUR CHARACTERISTICS of MAGNIFIERS:

1) POWER of MAGNIFICATION

The ability of the lens to increase the visual size of an object. The symbol X (times) is used to identify this factor. For example, a 3X magnifier triples the size of an image.

2) WORKING DISTANCE (FOCAL LENGTH)

In addition to power, a magnifier will also be classified for working distance. For example, 2X at a working distance of 5" 127 mm , means that the magnifier will provide double magnification an be in c ear focus when held at a distance of 5" (127 mm) from the object.

 

3) FIELD OF VIEW

The size of the area that is seen through the magnifier; the field of view decreases as the power increases.

 

4) DEPTH of FIELD

The distance that a magnifier can be moved from an object and still have the object in focus, the higher the power, the shorter the depth of field.

 

CORRECTIVE MAGNIFIERS

Certain magnifiers have lens systems which correct optical distortion or aberration that might otherwise be present as follows:

 

COMMON TERMS
AchromaticLens that eliminates chromatic aberration.
AplanaticLens that corrects for spherical aberration and coma.
Chromatic Aberration Inability of a lens to focus light of different colors at a point.
Coma Blurry appearance around an object viewed through uncorrected lens.
Corrected Lens system that corrects for distortions and aberrations to produce a sharp image.
Diopter Approximately ½ power (so, for example, 8 diopter = 2 power).
Spherical Aberration. Lens defect that produces an image that lacks