| The Extender-T serves a dual purpose. It is both a 2" 1.6x visual Barlow and a field-flattening photographic tele-extender. It can be used with the Takahashi TOA-130, TOA-150, and all FS series refractors that use a 2" focuser. It can also be used with Takahashi Mewlon Dall-Kirkham Cassegrains and with any other brand of quality refractor. This extender is not a simple two-lens achromatic Barlow lens, but rather a refined five-element optical amplification device. The 1.6x Barlow function is very useful with fast focal ratio refractors, as it lets you use long focal length eyepieces without having their exit pupils exceed the maximum dilated size of your eye’s pupil. The Extender-T produces a flat, color free, extremely high contrast image that can be used for high magnification lunar and planetary visual observation or photography and CCD imaging. An additional advantage of the Extender-T is that it corrects the image in the ultraviolet portion of the spectrum that is invisible to the eye, but is easily recorded by CCD cameras. Stars that radiate strongly in the ultraviolet appear closer to their naked-eye visual appearance when imaged on a CCD camera through the Extender-T. They do not have a bloated appearance on photos due to their normally invisible UV component being recorded by the CCD camera and added to the visual image. This feature only adds to the photo/visual capabilities of Takahashi scopes. Its five-element optical system is fully multicoated for maximum light transmission and contrast. There is a safety groove cut into the 2" chrome barrel. This catches the focuser thumbscrew and prevents the extender from slipping out of the focuser should that thumbscrew accidentally loosen while observing. Two chrome thumbscrews in the 2" barrel on the eyepiece side of the extender hold eyepieces and star diagonals firmly in place.
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