|TeleVue.com: Eyepiece Accessories > Barlows > Reviews|
Tele Vue's Big Barlow doubled the power but, like an optically perfect window, never gave any other indication that it was in the light path. The airy disc and surrounding diffraction rings were perfect, with no sign of astigmatism or coma. It will provide outstanding optical performance with all your eyepieces.
Taking award-winning images of distant planetary bodies requires extending your effective focal length to several meters. See Tele Vue's Image of the Day Winners page for examples.