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/
- Baader Heavy Duty T-2 QuickChanger (T-2 part #06A) # 2456313A
to connect it to the Zeiss Microbayonet ring-dovetail.
On the telescope side, you need either one of these nosepieces:
- Baader Nose piece 1¼" / T-2 (T-2 part #14) # 2458105
- Baader 2" / T-2 Nose Piece and Camera adapter (T-2 part #16) # 2408150
or you can screw it directly onto a Schmidt-Cassegrain 2"-SC-thread with
- Baader SC / HD Ultra Short T-Adaptor, 7mm optical length # 2958500B
You can use this roof prism with a binoviewer, too. But please note that even astro-grade prism still has the roof edge. So, while it will not produce double images even at high magnifications, there can be reflections at the roof which goes straight through the center of the field of view. So, if you have a bright object in the center, there can be reflections (just like there are spike in a Newtonian telescope caused by the holder of the secondary mirror). You can reduce them by moving the planet/star to the side, but they are part of the optical design. As binoviewers are often used for observing planets, we usually recommend to use a standard prism (which also requires less length).
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|Optical Design||Erecting Prism|
|Inner Connection (lens sided)||Thread, T-2 (M42 x 0,75)|
|Inner Connection (eyepiece/-camera-sided)||Thread, M34|
|Outer Connection (eyepiece/-camera-sided)||Thread, T-2 (M42 x 0,75)|
|Reflection surface||Sealed BBHS coating|
|Prism Glass (Type)||BaK-4|
|AR-Coating||Phantom Coating® Group|
|Image Orientation||Erect image, Non-reversed|
|Optical length (mm)||47.5|
|Clamping System||no clamp|
|Inner Diameter / Clear Aperture (mm)||31|