This four-lens Barlow is a telecentric system and offers outstanding imaging performance, even off the optical axis. This distinguishes it from conventional designs, where the image quality deteriorates noticeably towards the edge. This is a major disadvantage, especially with flat objects such as the sun and moon. The Barlow lens not only has high-quality optics, but also exemplary internal blackening. This is very important, as otherwise internal reflections would reduce the contrast. The lens edges are also flat, of course. This Barlow lens does not produce any additional colour aberrations and is therefore ideal for apochromatic lens telescopes.
The Barlow extends the focal length of the telescope by the specified factor and also shifts the focus further back. A special feature of telecentric Barlows is the parallel light exit, which means that the distance between the Barlow and the camera no longer changes the extension factor. This is advantageous if additional accessories, such as a filter wheel, are to be mounted in front of the camera.
