Overview and Recommended Use: Baader Star Diagonals

The most versatile tools: Baader Star Diagonals (T-2 and 2")

Manual and Recommended Use

A Baader star diagonal (both prisms and mirrors) can show you impressive images for a lifetime and offers more connection and configuration options than standard star diagonals.

Baader Planetarium's star diagonals not only offer the highest mechanical and optical quality, but also have the additional advantage of being part of a large, modular system. They enable very short adaptations as well as threads for direct connections to a telescope or a Baader focuser, as well as adaptation to a wide range of threads for torsion-free use with heavy or long accessories, such as binoviewers.

Decades of customer feedback led Baader Planetarium to create a seemingly overwhelming amount of adapters. But each adapter has its purpose. This is the reason why you can always find the optical length of each part in the product description, so that you can find the best solution for your needs.

To get the most out of them, we recommend that you spend a few minutes reading this brochure.

On the following pages you will find

  • a guide on how to choose coating and star diagonal type
  • an overview of the different models,
  • connection options to the telescope,
  • an overview of the eyepiece/camera side connection options
  • and a tabular comparison of the different models.


Please note: since January 2020 included with all 2" BBHS star diagonals: Baader 2" Safety Kerf nosepiece with 2" filter thread (#2408156 , € 43,-) with Baader proprietory Safety Kerfs for additional grip and security from inadvertent slipping.

Baader FlipMirror II Star Diagonal (#2458055 , € 228,-)

If you are looking for an even more flexible solution, take a look at the Baader FlipMirror II Star Diagonal (#2458055 , € 228,-) – its user manual shows how you can connect e.g. camera, eyepiece, autoguider or even a spectrograph at the same time!

2 thoughts on “Overview and Recommended Use: Baader Star Diagonals”

  • Rafa

    I have a TOA150. Could you please recommend the best diagonal to be used with a piece and I Bino viewer?
    I currently birthday BBHS mirror and I am having problems achieving focus, because I believe I have an aftermarket focus, sir, moonlight crawler, and he does not allow me to reach focus because of its extenders .
    Please , just recommend me the best I can get for my scope and I will order those .

    • Team Baader Planetarium
      Team Baader Planetarium December 13, 2022 at 11:11 am

      The shortest adaptation would be a T-2-prism, and the best quality would be Baader T-2 Stardiagonal (Zeiss) Prism with BBHS® coating (T-2 part #01B) # 2456095.
      A bino-viewer with a female T-2-thread can be directly screwed onto the star diagonal; for a bino-viewer with Zeiss dovetail you need Baader Heavy Duty T-2 QuickChanger (T-2 part #06A) # 2456313A, too.
      On page 20 of the manual of the MaxBright bino-viewer at https://www.baader-planetarium.com/en/downloads/dl/file/id/1614/product/4317/manual_baader_maxbrightr_ii_binoviewer.pdf you can find a descrition of how to determine the available back focus and to see if that adaptation is short enough.

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