T-2 BBHS® Astro Amici-Prism

The quality is the same for both prisms, but #2456120 (2") offers a larger free aperture and allows more field of view at low magnifications.

Jakość jest taka sama dla obu pryzmatów, ale #2456120 (2") oferuje większą wolną aperturę i pozwala na większe pole widzenia przy niskich powiększeniach

Optically it makes no difference which way around you install it. But you will need the right mechanical parts/adaptors that fit on the telescope on one side and for the eyepiece on the other side.

The glass path is the length which the prism (or any other optical element) adds or removes from the backfocus of your telescope. So, if you remove a prism with 50mm glass path from the telescope, the focuser has to be moved 50mm farther out. For the scale of the free diameter: The T-2-thread which is visible on the image is M42x0.75, which gives about 5mm for the aperture mask on each side. So, 31mm fo clear aperture remain.

There are many ways to connect the prism onto the telescope. From OTA to the prism I´d recommend the BTA adapter: https://www.baader-planetarium.com/en/baader-t-adapter-(bta)-for-sc-and-mak-telescopes-(t-2-part-21).html For 2" eye pieces our Clicklock clamp is for sure usefull #2956242 https://www.baader-planetarium.com/en/baader-2%22-clicklock-eyepiece-clamps.html The reducer is actually meant to be used it only for astrophotography purpose. Better take an eye piece with different focal length. The only limittation of the prism when combined with eye pieces is with long focal 2" models are used. However the human eye almost cannot detect obstructions of up to 30% so therefore it isn´t really a limit. The illuminated field is limited by the aperture of the prism but shouldn´t be overestimated.

Both of our Astro-Amici Prisms are produced with the same specifications. There is no difference in the quality of visual observation - the only difference is the size.

To use this or any other T-2 prism with the Binoviewer you need on the binoviewer side: - 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).