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Using a 2" barlow with 1.25" eyepieces

Started by Craig Burlette, 08/31/2003 06:06PM
Posted 08/31/2003 06:06PM Opening Post
I have a couple of 2" eyepieces and would love to have a 2" barlow in order to doubble my options. What is the efect of using a 2" barlow with 1.25" eyepieces? Is their any benefit to doing it this way? Any problems? Does anyone have an opinion on the University Optic 2" barlow? Is this a good choice or should I go for a teleview or any other suggestions?
Posted 08/31/2003 08:25PM #1
2" Barlows usually have longer focal lengths as compared to their nominal magnification factor. This is a GOOD thing. It leads to less vignetting and pupil throwout. Problems would be things like balance or perhaps protrusion into the light path of Newtonians with low-profile focusers--that sort of thing. I have no opinion on the current UO model. The one I tried was nothing special, but it was an earlier model. The Tele Vue Big Barlow is a safe bet, as is the Astro-Physics Barcon. And of course there is the Tele Vue 2" 2x PowerMate, which may work better with your longest focal length 2" eyepieces than the Big Barlow.
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Mike