Any reflecting telescope with classic coatings can attain a lifetime of 20 or 30 years - correct handling provided. The same accounts for our protected silver-coatings, whereas the position of a stardiagonal within the optical train does provide much better protection against environmental influences, compared to the exposed surface of a primary telescope mirror.
We do regard the benefit of the BBHS hardsilver coating to be quite noticeable, compared to the reduced spectral range offered by a dielectric coating. Please check in the Internet for statements that would verify our position. Or look for the very extensive tests on star diagonals, performed by William Paolini (see tab "Downloads".
Please read more on the properties of our star diagonals and our design philosophy here: http://www.baader-planetarium.com/en/blog/baader-bbhs-reflective-properties/
The amici/roof prisms that we supply with the BBHS-coating all are made according to the original optical specifications by Carl Zeiss. This is the reason for the high optical quality - good enough for high magnification work ( - and for the price as well).
Of course, it will usually end up in an uncomfortable position - but we offer the NexStar Locking Ring 2458270 which works as counter nut.
To attach the prism housing to your telescope, you may have to unscrew the eyepiece clamp, because otherwise it may hit the focus knob when you screw the prism onto the telescope.
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|Optical Design||Erecting Prism|
|Inner Connection (lens sided)||Thread, M48, M55, 2" (50,8mm)|
|Outer Connection (lens sided)||Barrel, Dovetail ring, S58, 2" (50,8mm)|
|Inner Connection (eyepiece/-camera-sided)||Thread, Clamp, M55, 2" (50,8mm)|
|Reflection surface||Sealed BBHS coating|
|Prism Glass (Type)||BK7|
|AR-Coating||Phantom Coating® Group|
|Image Orientation||Erect image, Non-reversed|
|Optical length (mm)||85|
|Inner Diameter / Clear Aperture (mm)||44|