Barlow lens


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Barlow lens

(bar -loh) An achromatic diverging lens (see achromatic lens) placed behind the eyepiece of a telescope, just inside the primary focal plane, in order to increase the effective focal length of the objective or primary mirror. This increases the magnification of the telescope so that a long-focus eyepiece may be used to give the higher powers needed to separate optical doubles, or for planetary observation under the best seeing conditions.

Barlow lens

[′bär‚lō ‚lenz]
(optics)
A lens with one plane surface and one concave surface that is placed between the objective and eyepiece of a telescope to decrease the convergence of the beam from the objective and thereby increase the effective focal length.
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References in periodicals archive ?
Those are excellent magnifications for deep-sky observing, and the 10-mm eyepiece together with a 2x Barlow lens shows fine planetary images at 130x.
The company has focused on serving its customers from the first Edmund Scientific catalog in 1943 to providing supplies for the space race in the 1950s and 1960s, including the 95-cent Barlow lens used in a color camera on the Apollo 11 lunar mission.
You put it in your telescope's eyepiece holder, usually with a Barlow lens to boost the image scale.
5x barlow lens giving a focal length of 3 000 mm, mounted on Skywatcher HEQ5 GOTO equatorial mount and a Meade Astrometric eyepiece.
An excellent choice for any burgeoning explorer, it's equipped with a rotating eyepiece turret holding 25-, 15-, and 6-mm eyepieces, along with a removable 18-mm image erecting eyepiece and a power-doubling Barlow lens, giving eight magnification powers to select from.
I was able to see Mars clearly through an eight-inch reflector, using a three times Barlow lens and a 20 mm eyepiece.
The time-honored solution to this ergonomie difficulty is to combine an eyepiece of moderately long focal length (and thus comfortable eye relief and an eye lens of reasonable diameter) with a Barlow lens or other image amplifier that doubles or triples the magnification.
Accordingly, planetary imagers generally use a Barlow lens or tele-extender to increase the telescope's focal length and magnification.
4" from the fainter component I can easily split it with my 8-inch telescope at 200-power by using a 2x Barlow lens and a 10mm Plossl eyepiece.
On the plus side, by not using any extension tubes I could get my Baader binoviewer and its own low-profile diagonal to reach focus without requiring any Barlow lens.
A 2x Barlow lens (also a plastic doublet achromat) yields a magnification of 50x.
However, it is possible to increase a scope's effective focal ratio (usually by a factor of 2) by inserting a Barlow lens between the focuser and the eyepiece.