The Barlow lens is one of the most popular accessories in the arsenal of astronomers, both professionals and amateurs. It is important in this field of activity. This device is a concave simple lens (negative) in shape, which greatly increases the effective magnification of the telescope. This element was invented in the 19th century by mathematician Peter Barlow. Hence the very name of the specified device.
Product use
Due to its versatility, the Barlow lens is quite widely used by astronomers of various qualifications. With this device, you can make the maximum possible increase in the object that is observed in the telescope.
This is an important property. For example, a 2x Barlow lens, when placed between the eyepiece and telescope objective,which gives a standard magnification of 100x, increases this figure to 200x. But since the useful increase depends on the stability and condition of the atmosphere, the use of this product is not always relevant. For example, if at 100x magnification air currents blur the image, then the Barlow lens, doubling the zoom level to 200x, will only aggravate the situation. The most effective is the use of this device in combination with a short-focus telescope. The Barlow lens will give this device considerable efficiency due to the fact that these telescopes have a limited capability, since they use standard short-focus eyepieces. The Barlow lens is also an indispensable tool for capturing planets with film or digital cameras.
It makes it possible to "stretch" small details or zoom in on the resulting image. Due to the thinner glass in the light path, a quality lens will give a more consistent result than projection through an eyepiece onto a photodetector.
Dignity
The main advantage of this fixture is that it increases the amount of magnification available. For example, if an astronomer has 10 mm, 18 mm, 26 mm eyepieces, then in the presence of a 2x Barlow lens, his instrumental stock is expanded by the indicated devices by 5 mm, 9 mm and 13 mm. It is economical in this case. In other words, one Barlow lens can replace three eyepieces.
Variety
The most common Barlow lenses aredouble (2x). However, the magnification factor for these products produced today is very diverse. The 3x, and 4x, and 5x Barlow lenses are quite common, and you can also find 1.5x and 2.5x. There are models with variable magnification from 2x to 3x. The use of these lenses can be complicated by insufficiently high offset focus of the telescope.
Tip
When selecting the right Barlow lens for an existing telescope, special attention should be paid 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 eyepiece seats. In order to obtain a twofold magnification of the image with a 2x Barlow lens, it is necessary to place it between the diagonal mirror and the eyepiece. These products of really high quality should have enlightenment and ideally it should be multi-layered.
