The Barlow lens is one of the most popularaccessories in the arsenal of astronomers, and both professionals and amateurs. It is important in this field of activity. This device is in the form of a concave simple lens (negative), which greatly increases the effective magnification of the telescope. This element was invented in the XIX century by the mathematician Peter Barlow. Hence the very name of this device.
Due to its multifunctionality, the lensBarlow is quite widely used by astronomers of various qualifications. With the help of this device it is possible to realize the maximum possible increase in the object that is observed in the telescope.
The main advantage of this deviceis that it increases the amount of available magnification. For example, if an astronomer has eyepieces of 10 mm, 18 mm, 26 mm, then if the Barlow 2x lens is present, his instrument stock is enlarged by 5 mm, 9 mm and 13 mm. This is economical in this case. In other words, one Barlow lens can replace three eyepieces.
The most common lenses of Barlow steeldouble (2х). However, the increase multiplier for these products produced today is very diverse. The Barlow lens 3x, and 4x, and 5x is quite common, and you can also find 1.5x and 2.5x. There are models with variable magnification from 2х to 3х. To complicate the use of these lenses may not be sufficiently high focus of the telescope.
When selecting the necessary Barlow lens forThe existing telescope should pay special attention to the diameter of the landing sleeve. Its size can be 0.965, 1.25 or 2 inches. It should be identical to the diameter of the focuser and the position of the eyepieces. In order to get a double image magnification with the Barlow 2x lens, it is necessary to place it between the diagonal mirror and the eyepiece. These products of really high quality should have an enlightenment and ideally it should be multi-layered.