Baader FlipMirror II Star Diagonal

  • Streamline your workflow with this multi-use diagonal
  • Adjustable ports for any accessory
  • Perfect for both imaging and visual
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  • Regular price $227.00

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Baader FlipMirror II Star Diagonal

Experience the 'Swiss Army Knife' of star diagonals that is the Baader FlipMirror II Star Diagonal. With 3 adjustable, configurable output ports and a high-quality flip mirror, the FlipMirror II becomes the heart of your equipment system. Its multitude of adaptations give the imager and visual astronomer practically limitless ways to couple and operate multiple instruments, cameras, guiders, OAGs, eyepieces, and more!

Baader Flip-Mirror II Star Diagonal Diagram Full

The Baader FlipMirror II Star Diagonal has a straight-through build (S52, M48, and T-2 on both sides) for full-frame cameras, spectrographs, or other instruments. The T-2 threads are also adjustable to ensure your ability to alter this however you will. The rotatable M48 connection rings can be fixed in the optimum position to rotate any accessory around the optical access and is constructed of hardened, stainless steel on front and rear to be backlash-free with the FlipMirror's housing.

Telescope auxiliary instruments cover a wide range of interests, from a sole eyepiece, via camera use, to high-end spectroscopy. Unfortunately, every telescope just features one exit port. This causes relentless manual exchange of parts in the dark, causing huge time loss, wear on the parts - and "nerves". And whenever you start controlling your telescope remotely - the single port becomes a painful reality. This product is guaranteed to improve your workflow--especially during astrophotography, which is ultimately the main goal of the Baader FlipMirror II. 

The BFM II lets you switch between a straight light path for a camera or other measuring instrument and an angled light path for something like an eyepiece. Additionally, a calibration lamp for spectrographs or OAG can be connected at the AUX port on the bottom of this device.


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  • Baader FlipMirror II Star Diagonal
  • Laterally adjustable T-2a Top Ring
  • 2x M48i / S52 Dovetail ring made of hardened stainless steel
  • Reducing ring M48a / T-2i
  • Reducing ring M48a / T-2a
  • Inverter ring M48a / M48a
  • Pin type face wrench for M48 / t-2 and M4 counter nuts
  • 3 mm screwdriver for M 4 brass adjustment screws
  • 4x hex keys
  • Bottom flange for OAGs or calibration lamp
  • Dust cap for bottom flange
  • 2xM48 dust caps
  • T-2 dust cap
Customer Reviews
4.5 Based on 2 Reviews
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Jeff R.
United States United States
Extremely versital

Great addition to any astrophotography kit. After a little bit to configure all the connections with illuminated eye piece on the vertical port, camera connections on the back port, and guide camera on the bottom port- I can easily switch between viewing, photography, and built in guiding without having to swap out pieces.

United States United States
Great Product, but requires many expensive adapters

The only reason I'm writing this review is to let future buyers know that you will need to buy at least 3 different adapters if you want to use this product (if you don't already have adapters). First you are going to need a nozzle to attach to your telescope with a T2i threading (min is 1.25" so I bought the T2i/1.25" Nozzle buy Baader for $35). To attach a Camera you will need an adapter that connects to a M48i or a T2a (I am using a NexImage 5mp by Celestron so I needed a T2i/1.25" eyepiece mount for $35). Lastly you will need an Eyepiece mount that has a MicroFocuser so that the eyepiece lens and the CCD sensor are at the same focal length so that when you flip up the mirror you don't have to focus the camera after focussing the eyepiece (I'm using 1.25" so I bought the Baader Eyepiece Holder with MicroFocuser and T2i threading ). the "i" means a Female/Internal threading and the "a": means a Male/External Threading. The instructions are kind of difficult to understand as far as knowing what adapter to buy but here is what i figured out: The top of the flip mirror is T2a that accepts T2i Adapters; the telescope side is M48i with an M48a/M48a adapter so that, when you buy it, the telescope side is M48e; The camera side is M48i with an M48a/T2i adapter which I unscrewed and put on the telescope side so that I could attach the 1.25" Nozzle with T2a onto it, also, attached to the M48a/T2i adapter is a T2a/M48a adapter so that the Camera side (just like the telescope side) is M48a on the outside when you buy it. After switching the M48e/T2i adapter to the telescope side I attached the M48e/T2e adapter so that T2a was on the Camera side and I attached the Baader Ultra Short Eyepiece Holder 1.25". It was pretty complicated for me to figure out and with taxes and shipping it cost me another $170 to get the correct adapters to just use the Flip Mirror. I understand they don't ship it with adapters because they don't know what kind of gear you have, but it would be nice if they sold adapter kits or wrote in their instructions a guide or table that had three columns that showed what adapters you would need for your specific setup. My setup is basically the "beginners" setup that is used to attach a 1.25" Telescope to a 1.25" Eyepiece and a 1.25" Camera. I feel like they should at least provide it as a kit for 1.25" setups like mine.