The practical result is that inserting a Barlow lens magnifies the image.

Astronomical Barlow lenses are rated for the amount of magnification they induce.

Teleconverters are variations on Barlow lens that have been adapted for photographic use.

In microscopy the Barlow lens is used to modify the working distance and the magnification.

The effects and uses of the telecompressor are largely opposite to those of the teleconverter or barlow lens.

Most commonly, Barlow lenses are 2x or 3x but adjustable Barlows are also available.

A derivative of this work is still known today as the Barlow lens and is a widely used piece of astronomical equipment.

If a diagonal or Barlow lens is used before the eyepiece, the field of view may be slightly restricted than using the eyepiece alone.

In effect, a Nagler is a superior version of a Barlow lens combined with a long focal length eyepiece.

The power of an adjustable Barlow lens is changed by adding an extension tube between the Barlow and the eyepiece to increase the magnification.

Together with Peter Barlow, he also invented an afocal system to extend the focal length of telescopes, called the Barlow lens.

A true telephoto lens uses a configuration similar to a Barlow lens to obtain a shorter tube length for a given focal length.

The Barlow lens, a negative achromat magnifier invented by Peter Barlow in 1833, is still sold to increase the eyepiece magnification of amateur telescopes.

A real barlow lens is not a single glass element, because that would generate chromatic aberration, and spherical aberration if the lens is not an asphere.

In its astronomical use, a Barlow lens may be placed immediately before an eyepiece to effectively decrease the eyepiece's focal length by the amount of the Barlow's divergence.

These work by means of a dual lens system of a plano-convex and a plano-concave lens fitted into an eyepiece adaptor which superficially resembles a Barlow lens.

The amount of magnification is one more than the distance between the Barlow lens and the eyepiece lens, when the distance is measured in units of the focal length of the Barlow lens.

The Barlow lens, named after Peter Barlow, is a diverging lens which, used in series with other optics in an optical system, increases the effective focal length of an optical system as perceived by all components after it is in the system.

Tele Vue also manufactures special nebula filters, barlow lenses, special image amplifiers known as Powermates, the "Paracorr" coma-corrector for "fast" (f/5 and below) Newtonian telescopes, and the "Dioptrx," a special lens that fits over most Tele Vue eyepieces to correct eyesight astigmatism.