TeleVue Barlows and Powermates
TeleVue Barlows and Powermates are used to amplify or enlarge images in both visual and imaging applications. Barlows are powerful tools for extending an eyepiece collection at minimal cost, however; there are certain practical limitations to their application. The simple negative element Barlow increases eyepiece eye-relief. With short focal length eyepieces the effect is negligible. However, on long focal length eyepieces the exit pupil position moves well beyond the designer's intended position, resulting in vignetting with many eyepieces. This is why shorty Barlows in particular often vignette and degrade long focus eyepieces.
The 4-element TeleVue Powermate image amplifier picks up where the Barlow concept can go no further. Powermate is a technically universal solution, using a positive field lens to redirect field rays. The result is an exit pupil that stays where the eyepiece designer intended. With freedom from aberrations, greater magnification potential, and compact size, the 4-element TeleVue Powermates raise the bar for image amplification.