Bausch & Lomb 20x Coddington Magnifier
Correction in the Coddington magnifier is achieved through the use of a single thick lens with a central groove diaphragm. This provides for sharp, crisp images.
A swing-away, nickel-plated case protects the lens and serves as a handle.
- focal distance of .5"/1.3 cm
- 80 diopters
- 12.5 mm lens diameter.
The Bausch & Lomb 20x Coddington Magnifier has extremely
strong magnification for a hand held loupe but has limitations too.
Make sure you need this much magnification.
The information below is true of all high magnification lenses
including cameras, telescopes, and magnifiers. It is NOT a unique
characteristic of the Bausch & Lomb 20x Coddington Magnifier.
The strong magnification comes at the cost of a very small lens. The
lens diameter is what collects the light. With a small lens diameter it
doesn't collect much light. A larger lens would really have to be
larger and much more expensive. A 10x power loupe gives very nice
magnification with a lot brighter image.
The lens has a very short focal distance, the point at which the image
appears in focus. The distance at which the object appears in focus is
one half inch (0.5''). Your hand will be one half inch away from the
object and your hand will be blocking much of the light available to
this small lens.
The lens offers very little Depth of Field. Depth of Field is the
vertical relief that appears in focus. The focus slop if you will. The
more magnification, the less Depth of Field. If the object you're
viewing is rough, like a rock or a mineral, you'll have to keep moving
the object towards and away from the loupe. A 20x loupe is good for
looking under high magnification, at the surface of rocks and minerals,
the faces of gemstones, coins, stamps, cloth thread counts and other
objects where you must have high magnification.
This much magnification would not be useful for reading.
A 20x loupe should NOT be the only loupe that you have.