| Like all binoviewers, the TeleVue Bino Vue uses a single beam-splitting prism and two porro prism systems to provide correctly oriented images when viewing with two eyepieces. In general, prisms introduce spherical aberration, color fringing, and edge of field astigmatism when they are placed in a converging light path such as that coming out of a telescope and passing through a binoviewer. The thicker the prism path and the faster the telescope focal ratio, the more the image is adversely affected.
The TeleVue Bino Vue prism corrector is a multicoated auxiliary lens system designed to correct these aberrations when the Bino Vue is used without the 2x image amplifier. (The 2x amplifier acts to correct the aberrations on its own by effectively increasing the focal ratio and causing the light cone to converge more slowly as it passes through the Bino Vue, so the correction provided by the prism corrector is not needed.) It essentially compensates for binoviewer prism aberrations with any speed telescope. The lens cell of the corrector threads into the base of your TeleVue Bino Vue body. It allows optimum image quality with the Bino Vue, even when used at the highest magnifications. The corrector has very little effect on magnification or focus position when used with the Bino Vue. It can be used in all TeleVue star diagonals without fear of hitting the mirror.
TeleVue considers the prism corrector to be essential to get the best high-power performance possible when binoviewing with telescopes faster than f/10. They consider the prism corrector to be essential for fast systems with focal ratios ranging from f/4 to f/6; helpful for moderate speed systems from f/8 through f/10; but not necessary with slow systems ranging in speed from f/12 to f/15. |
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