Deep-Sky Astrophotography with the FlipMirror II star diagonal

The Baader FlipMirror II (BFM II) in action

The Baader FlipMirror II Star Diagonal (#2458055, € 190,09) is not only an accessory for "experts" but also a useful tool that makes the work of every amateur astronomer – especially the astrophotographer – easier.  First and foremost, the BFM II is designed to fully replace your standard star diagonal so that you can continue to observe as normally with any good star diagonal. But with the BFM II you also have the freedom to create your own photo system immediately – or step by step – and have it ready for immediate use on the telescope.This saves a lot of time and nerves. We would like to introduce to you the countless possibilities of this new product in several blog posts in loose order. We start with the field of application for which there is certainly the most interest: Deep Sky Astrophotography.


Baader Flip Mirror II star diagonal, equipped for astrophotography

Deep Sky Photography with Off Axis Autoguiding

The FlipMirror II star diagonal is far more than a simple flipmirror, as these accessories were known in the past. Thanks to the very high-quality, fine-optically polished mirror and the large T-2, M48 and S52 connection threads, as well as the connection possibility on four sides, it offers completely new possibilities to the astrophotographer to make the work easier.

Of course, the connection to any desired telescope of any size is possible. The same applies to cameras. All conceivable camera models, DSLR as well as bridge, system and astro cameras of almost all manufacturers can be attached.

In the picture on the right the camera is mounted at the rear end of the FlipMirror II, so that the light from the telescope can come in straight and unreflected when the flipmirror is "flipped up". If the hinged mirror is "flipped down", the light from the telescope is directed into the eyepiece instead of to the camera. With a variety of T-2 tubes and adapters, the eyepiece can be placed at the same distance as the camera so that the image is sharp in both the camera and the eyepiece. This means that the eyepiece can be used to center the object for the camera and (pre-)focus it for image acquisition.

FlipMirror II with Off Axis Guider (in this example with UFC filter slider)

The Baader UFC-System can be mounted before or after the BFM II, depending on your needs

Usage with Off-Axis-Guider

An Off Axis Guider can be attached to the lower end of the BFM II (e.g. Off Axis Guider for Baader FlipMirror II (BFM-OAG) (#2956951, € 95,53) ). A small prism protrudes from the BFM-OAG into the FlipMirror II, which is located below the hinged mirror. The prism directs a small part of the telescope's field of view, which is not captured by the camera, to an optional guiding camera - regardless of whether the mirror is flipped up or down.

In this way you can use the Baader FlipMirror II Star Diagonal (#2458055, € 190,09) for Off Axis autoguiding on every telescope. This also works if you want to work with narrowband filters, whose image is usually too dark for autoguiding. But due to the flexible connection possibilities of both the FlipMirror II and the Baader UFC system, filters can even be mounted behind the FlipMirror II, i.e. directly in front of the camera and not in front of the autoguider.

The FlipMirror II is a multi-purpose tool which provides many options and ports. It spares you a guiding scope as well as continous changes of eyepiece and camera. What could be more useful?

Coming Soon: Planetary imaging with the FlipMirror II star diagonal

About the author

Michael Risch

Michael Risch has been interested in astronomy since he was 6 years old, and in 1981 became a member of the Association of Amateur Astronomers in the Saarland. There he accompanied the construction of the observatory Peterberg as a member of the board. As co-founder and first webmaster of, he contributed many ideas to the first German astronomy portal and, as a lifelong academic lecturer, has guided many "Northern lights and stars" tours into the Arctic Circle. Astronomically, he has dealt with planets and comets, sun, deep sky and TWAN-style photography, including many long-distance travels, amongst others to 7 total solar eclipses. Michael has published many of his own photos and articles in journals and authored with his colleague Martin Rietze for "Color Foto" chapters for the books Fotoschule (Photo School) and Extremfotografie (Extreme Photography).

He is part of the observatory project team at Baader-Planetarium and is booked for lectures within the Celestron distribution in Germany and abroad. He is also a consultant for high end mounts, telescopes and much more.

View all posts from Michael Risch
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