Barlow Lens is an optical accessory used for telescope observations with visual and photographic observations. It allows you to achieve a higher zoom range and higher image quality.
What is the Barlow lens for? Unlike other astronomical elements, it allows you to achieve an increased focal length through the lens of the telescope. This effect is achieved due to the built-in negative diverging lens. Biconvex glass with a negative effect reduces the angle of the rays converging from the aperture. Due to this, the focal length increases.
The main indicator of efficiency is the multiplicity of increase.Usually used models from 2 to 5 levels of multiplicity. The magnification is the degree of growth of the focal length of the aperture. There are models with not very common multiplicity of 2.5 or 2.25. The average multiplicity level - 3 - corresponds to the models of observational telescopes. Zooming over 3x allows you to take high-quality photos. Barlow's 2x lens is the most common option in production and sales.
The optical unit of the lens includes a housing with an optical part inside. Factory equipment includes the following items:
- a metal case (usually black) with a company sticker and model designation;
– the clamping screw of metal that secures the eyepiece, the diameter of the planting of 1.25”
- the thread on the upper part of the body (T-shaped) allows you to attach the lens to the camera or other photographic equipment;
- a 1.25 ”threaded adapter ring, which allows to mount the entire optical unit and filters for light with the same thread size;
- a groove designed to protect the part from falling out in case of incomplete clamping as part of the telescope focuser;
- glued negative achromatic lens in the composition of the optical unit, designed for dispersion, with a total diameter of 2.4 cm. The light diameter is 2.2 cm and the width is 0.7.
In the working position, the lens is placed with its flat part outward, and convex - inside the telescope, the parts are blackened from the end of the edge. On the surface of it you can find many layers of enlightenment in blue-violet shades. Attaching to the optical unit is carried out by a sealing ring, which is wrapped in a thread.
A part manufactured in China is usually referred to as a Barlow T-Adapter 1 × 1.4 ”with a specific model number. Overall height is 7.3 cm in full assembly.
Consider a model with a twofold increase. The Barlow lens is made up of two elements, has a size of planting 1.25 mm eyepieces with magnification factor 2. A T-thread, and enlightenment. Its weight is about 90 g. the Scheme Barlow lenses includes a built-in filter. A feature of this device is the ability to unscrew the entire optical unit together with a magnifier and put any filter of the desired size into an empty unit.
The results are a pleasant surprise: this option allows you to reduce the brightness of the moon if installed polarizing filters and sun spots become more contrast (especially when you use special filters Baader Solar Continuum). Contrast detail on small planets increases with the use of colored filters.
The main functions are performed at a decent level. If the lens is removed with the entire optical unit, then there remains only a sleeve with a light filter, which in the complex can serve as an adapter.
The principle of operation
It is a multifunctional device that allows to perform astronomical observation & photography compatible with SLR camera. The T-thread allows you to attach via the T-ring which serves as the adapter on any model of camera. An astronomical photo can be taken in any focus, even without using a Barlow lens - the user can unscrew the entire optical unit with a lens at any time. At the same time, an empty sleeve can work as an adapter — connect the focus of the telescope and accept any light filter for direct focusing through the existing light filter.
This is a budget option astronomical device for producing high quality contrast images. The device allows for a wider removal of the pupil and to suppress in this case arising in the process of increasing the aberration.
Device with adapter
Lens Celestron 2x Barlow with T adapter has no special differences in the functions from the normal pattern, but allows for small differences in weight due to the presence of the adapter. Image both lenses are identical, differences in the structure of the enlarger there. The same structure as the quality mechanics and optics, provides a positive level images with sufficient sharpness, clarity and the resulting increase to 160 times.
The use of an enlarger with an adapter allows you to view Jupiter and its main belts, of which there are four, as well as the Great Red Spot.A well-received image of the rings of Saturn with belts of clouds. Combination with another eyepiece (for example, SkyWatcher) makes it possible to view the lunar and solar surfaces with craters and various formations.On the sun are visible separate flashes, spots, torches. The image quality is achieved by the joint operation of two lenses - their pairing reduces aberration, eliminates additional chromatism. Barlow's devices work worse when they work with a wide-angle eyepiece. It is much more convenient to combine them with eyepieces of small removal and simple schemes: Ramsden, Kellner, Plessla eyepieces and others.
What is the Barlow lens reviews? Most buyers talk about the positive qualities of the product.These are magnifiers that are good, inexpensive and affordable for beginners, which provide the user with all the necessary functionality for shooting and performing astronomical observations and experiments. The variant with the adapter allows you to more deeply and significantly view the space objects with maximum clarity and detail. The choice of model depends on the needs of the researcher or photographer and his material capabilities.