| This short focal length Takahashi eyepiece uses a proprietary five-lens optical design to provide a high magnification capability with exceptional sharpness and contrast. The eyepiece uses an ED (Extra-low Dispersion) glass element for outstanding color correction. This five-element Takahashi is similar in its optical performance to a classical four-element Abbe-type orthoscopic. It has the high contrast, low ghosting, flat field, and excellent edge to edge image sharpness for which orthos are famous – but has a 52° apparent field of view that far outstrips the 40-42° field more typical of a conventional ortho. The 7.5mm Takahashi makes an excellent lunar and planetary eyepiece with scopes of all optical types – refractors, Schmidt-Newtonian and Dobsonian reflectors, catadioptrics, and more. Its high contrast and low ghosting also excel at splitting close binary star pairs, resolving globular clusters, picking out small planetary nebulas against a stellar background, etc. It typically provides the maximum useful power with an f/15 Maksutov-Cassegrain. |