With the usage of barlow lenses , you can extend the equivalent focal length of telescopes and hence increase the magnification of your observed targets. Subsequently, you can use lower power eyepieces in Barlows to act as much more powerful eyepieces, but retain the larger ocular size and more comfortable viewing that comes with lower power eyepiece designs.
Due to their two lens design , these Barlow lenses provide a brilliant image quality for the whole visual field and are suitable for observations and photography. The black coloured Barlow element cell in this BRESSER Barlow Lens 2x 31.8mm/1.25," can be unscrewed and has the same thread as 1.25" filters, allowing it to be mounted in 1.25" eyepieces, t-adapters and other accessories, giving you flexibility of use and the ability to vary magnification in different accessories. For instance, the black Barlow cell screwed into the average length nosepiece of a standard push fit t-adapter will give around 1.6x magnification on an attached DSLR. This can be very useful when trying to get to photographic focus with some Newtonians and Solar Telescopes, which lack the necessary amount of in focus travel to get a camera to a prime focus position.