Planetary Imaging with the FlipMirror II Star Diagonal

Using the Baader FlipMirror II Star Diagonal (BFM II) at the Telescope

The Baader FlipMirror II Star Diagonal (#2458055, € 195,-) is not only an accessory for professional users, but much more: It is a helpful tool for every amateur astronomer – especially for astrophotography.

First of all, the BFM II is designed to completely replace your standard star diagonal, so that you can keep observing as usual, just like with every good star diagonal. But the BFM II gives you much more options. You can create – from the beginnig, or step-by-step – your own system for photography and keep it always ready-for-use at your telescope. This will save you a lot of time and nerves. In the next months, we want to show some of the many options of this new product here.
In this article we cover planetary imaging.

What are the benefits of the FlipMirror II for planetary photography?

The Baader FlipMirror II Star Diagonal (#2458055, € 195,-) with two M48/T-2-ports is a great tool to make imaging the planets easier. Here, we'd like to show you two possible fields of application.

1. Observe and take photos

The basic purpose of the FlipMirror II Switch easily between eyepiece and camera.

The basic purpose of the FlipMirror II Switch easily between eyepiece and camera.

Attach a camera to the back side of the BFM II and an eyepiece on its top. So it is easy to center a planet on the small chip of a camera module – and with the turn of a single knob, you can switch between "photography" and "visual observing". There is no need to replace the camera with the eyepiece again and again! Just set both camera and eyepiece once to the same focus point, and the coarse focussing is history: If you can see the planet in the center of your eyepiece, you'll see it with the camera, too. Much too often, the de-focussed image of the planet is so large that you can't recognize it at all on the display after switching from the eyepiece to the camera. Take a cross-aim eyepiece to center and focus the planet in both eyepiece and camera. This way, it is much easier to hunt the planets in a telescope without perfect tracking, too – if you have ever tried to photograph the planets with a Dobsonian, you'll be amazed!

Not too mention that the camera is placed in the main focus of your telescope, and the function of the FlipMirror II as star diagonal is only used for a comfortable viewing position when looking through the eyepiece.

Of course, you can also use the Stop Ring 1¼" (T-2 part #30) (#1905131, € 25,-) and if necessary Baader 1¼" - 31.8mm nosepiece extension with 1¼" filter thread on both sides (T-2 part #05) (#1905130, € 14,49) to bring camera and eyepiece into the same focus position whenever you use it – but then, still, the orientation of the camera changes whenever you remove it from the focuser. And at which telescope is there ever enough place to put something down? With the FlipMirror II, everything is exactly where you need it - at the telescope!

The FlipMirror II, configurated for professional planetary imaging: A monochrom camera at the straight-through light path, and a colour camera at the upper port

The FlipMirror II, configurated for professional planetary imaging: A monochrom camera at the straight-through light path, and a colour camera at the upper port

2. Hi-Res planetary photography with two cameras

The FlipMirror II is perfect to solve a problem which every photographer of the planets must face: If you use a colour camera, you don't have the highest possible resolution, because of the Bayer Matrix – 50% of the pixels are sensitive for green and 25% each for red or blue. For the best resolution, it would be nice to take e.g. a hi-res image of Jupiter in monochrome for luminance and combine it with the image of an RGB-camera to add colour. But for this you need to switch between two cameras, and you need time to connect, focus and operate them. This would be no problem if Jupiter wouldn't rotate around its axis in only ten hours – more than twice as fast as our Earth rotates.

If you capture several sequences qith a video module and have to wait for good seeing between the sequences, this may take half an hour or so. During this time, Jupiter keeps rotating, and the images can't be stacked any longer. But if you have a colour camera at one port of the FlipMirror II and a monochrome camera at the other port, you don't waste any time on switching the camera, orientating it and so son. You can switch between both cameras in an instance, and the chances for good results are much better than if you have to waste time for exchanging the cameras in your single focuser.

There is one more intersting option for advanced planetary photographers: If you photograph in UV or Methane on a regular base, you know how hard it is to focus the dim image. If you attach two cameras with the same focus plane to the FlipMirror II, you can use the one for monochrome or RGB-images also to quickly focus the second camera. So, even hard areas of observation get better accessible.

About the author

Michael Risch

Michael Risch has been interested in astronomy and spaceflight, since he saw the last moon landing as a child. In 1981, he became a member of the Association of Amateur Astronomers in the Saarland and, as a member of the board, accompanied the establishment of the Peterberg Observatory. As co-founder and first webmaster of, he contributed numerous ideas and reports on astronomical and spaceflight topics to the first German astronomy portal. He has been practicing planetary, comets, solar, deep sky as well as TWAN style photography, and has been on many long distance trips, among others to 7 total solar eclipses. As a long-time science editor, he has led "Northern lights and stars" trips to the Arctic Circle. Michael has published many of his own photos and articles in professional journals and has written chapters for the books chapters for the books Fotoschule (Photo School) and Extremfotografie (Extreme Photography) with his colleague Martin Rietze for "Color Foto".

At Baader-Planetarium he is part of the observatory project team and is booked for lectures in Germany and abroad. Furthermore, he is an expert consultant for observatories, domes, high end mounts, telescopes and much more.

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