The Amici Prism has long been favored as the best choice for producing correctly oriented images in refractors and cassegrain type telescopes. However, the production of an amici prism is complex and requires a much higher level of quality than a standard mirror or right angle prism diagonal. Prism faces must be polished smooth, flat, and very accurately located at the proper positions and angles. The sharp roof edge must be made vanishingly fine. These demands on prism quality are the prime reason why even expensive amici prism diagonals have developed a deserved reputation for poor image quality. Even the so-called premium quality amici prisms typically produce astigmatic or asymetrical images and display a bright prominent central diffraction spike (the roof edge diffraction spike in the Baader Amici is extremely faint). Also, making matters worse, undersized prisms are used to save cost and large housings give the false illusion of a large clear aperture (as is the case with most so-called 2" amici star diagonals available today).
Baader Planetarium produces what we think is easily the finest amici prism star diagonal available today. The prism has been made to the original Zeiss specifications ** that were used for their famous amici diagonal turrets, in order to provide image quality that suffers from none of the defects found in commonly available correct image amici diagonals. The finest 7-Layer Multi-Coatings ensure the image is bright and contrasty, and the oversized prism provides the full clear aperture of 1.25”! The precision machined aluminum housing provides a stress free mounting and precise location for the prism, unlike the typical weak plastic or crudely cast and machined housings found on lesser diagonals. The end result is a correct image diagonal that is good enough for more than just high-quality terrestrial viewing.
Correct image diagonals have been used traditionally for terrestrial viewing, and limited to low (under 100X) magnifications. The high quality of our diagonal lets you use much higher magnifications without aberrations or image breakdown for both astronomical and terrestrial uses. The diagonal is perfect for matching astronomical charts or sketching correctly oriented planetary detail. It also functions well with the Baader Maxbright BinoViewer and Baader/Zeiss Mark V BinoViewer, to provide correctly oriented binoviewing. Many users have commented to us on how wonderful it is to enjoy correct-image views of all planetary and deep sky objects, and that they would not go back to traditional star diagonals. Finally, views that match star and lunar charts!
One of our customers (a professional optical engineer) turned to us when he needed a high quality correct-image diagonal. This same customer had first tried a competitive (so-called 2") amici star diagonal and had found it useless due to its poor image quality. He was thrilled with the quality of the Baader Amici, and sent us his detailed comments and Interferograms from his WYKO digital interferometer. Please click the link below for his report.
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AMICI OPTICAL REPORT
* PLEASE NOTE: The Baader Amici Star Diagonal incorporates standard T-2 threads at the input and output faces, and is provided as a basic component, without any input or output fittings. This permits the diagonal to be used as a compatible component along with the other Baader Planetarium T-2 accessories, like the Baader Maxbright Binocular Viewer. This also enables you to configure the diagonal to exactly suit your needs, and to fit 2" or 1¼” eyepieces, and focusers. Please see Eyepiece Adapters, Rings for applicable fittings, and the T2 Diagonal Configuration page for detail on specific configurations. The effective optical path length of the base Amici Star Diagonal is approximately 64mm. To calculate the total path length of a particular configuration, see ASTRO T-2 System Specs for a detailed listing of threads and path length dimensions for all of the Astro T-2 system components.
** Many production divisions of the former government owned Carl Zeiss Jena have been privatized. The Zeiss core enterprise today concentrates on production of finished ultra-high end optical and medical devices. Many of the thousands of standard components are delivered to Jena "just in time" like any car factory works today. The opticians and skilled people that once made up the company are still alive (and kicking) and as a result many highly capable optical companies have developed in this region, still producing optics in the old Zeiss tradition. Baader has people employed who formerly worked at Zeiss Jena and they still use their contacts to existing optical shops there for the production of their prisms and all optical components for the Mark V binocular, all produced to the original exacting Zeiss specifications and processes.