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FlipMirror II (BFM II) Star Diagonal

Name: FlipMirror II (BFM II) Star Diagonal
SKU: 2458055
Price: 228 EUR
Availability: InStock

In Stock

11 Reviews

33 Answered Questions

# 2458055

€228.00

Price excl. German VAT tax (19%): € 191.60

EN-Instruction manuals

Instruction Manual: Baader FlipMirror II Star Diagonal

Size: 1.3 MB

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Baader-FlipMirror II Star Diagonal (BFM II) with precise surface-mirrored flip mirror with multi-layer Al coating and three ports:
- Straight-through (S52, M48 and T-2 on both sides) for full-frame camera, spectrograph, or other instruments
- Adjustable T-2 thread on top for eyepiece clamps, video modules (up to 32 mm image circle) or even a binoviewer
- Bottom flange for the optional Off-Axis-Guider or for an optional calibration lamp for spectroscopy
Shortest possible overall length for any application – compatible with a large number of adapters from the Baader Astro T-2 system, the M48 system and the UFC system (Universal Filter Changer)
Rotatable M48 connection rings made of hardened, stainless steel on front and rear

FREE DOWNLOAD:
3D-printable FlipMirror II Mirror Holder

Further information and download link can be found here.

Baader FlipMirror II Star Diagonal

Various ports – variable work

Telescope auxillary 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.

Improving workflow, especially during astrophotography is the goal set out for the BFM II. This is not just a simple flip mirror but much more, as there are three ports to be put into action. The BFM II also enables the precise adjustment of all light paths.

BFM II makes your single telescope port variable – to suit your various interests.

The FlipMirror II Star Diagonal allows a variety of permanent adaptations to your telescope 1 . Use the rotary knob 2 to switch between the rear port 3 and the top port 4; you can use an optional toothed belt to operate it with a motor (not included). An autoguider or a calibration lamp can be connected to the bottom port 5.

Baader-FlipMirror II Star Diagonal (BFM II) offers you three ports:

Straight-through (S52, M48 and T-2 on both sides) for full-frame camera, spectrograph, or other instruments
Adjustable T-2 thread on top for eyepiece clamps, video modules (up to 32 mm image circle) or even a binoviewer
Bottom flange for the optional Off-Axis Guider for Baader FlipMirror II (BFM-OAG) (#2956951 , € 122,- ) or for an optional calibration lamp for quick calibration of spectra without removing the spectrograph.

The rotatable M48 connection rings are made of hardened, stainless steel on front and rear. They are adapted backlash-free to the BFM housing, so that they can be fixed in the optimum position to rotate any accessory around the optical axis. The BFM II is compatible with a large number of adapters from the Baader Astro T-2 system, the M48 system and the UFC system (Universal Filter Changer)

General Function of the FlipMirror II Star Diagonal

The heart of the BFM II is a precise surface-mirrored flip mirror with multi-layer Al coating, which can be used as any regular gigh-end star diagonal for visual observations and for high-resolution images with cameras with small pixels. In addition, the BFM II lets you switch between a straight light path (Position A) for a camera or other measuring instruments and an angled light path (Position B), e.g. for an eyepiece. The following figure shows how it works. In addition, a calibration lamp for spectrographs or an Off-Axis-Guider pickoff-prism (that is not affected by the mirror position) can be connected at the AUX-port on the bottom. The back of the flip mirror is also Al coated and masked to direct the light of an optional calibration lamp onto the slit of a spectrograph.

Scope of Delivery of the Baader FlipMirror II Star Diagonal:

Baader FlipMirror II Star Diagonal – with fine-optically polished, movable mirror
Laterally adjustable T-2a top ring
2x M48i / S52 Dovetail ring made of hardened stainless steel # 2958552
Reducing ring M48a / T-2i # 2958553
Reducing ring M48a / T-2a # 2958554
Inverter ring M48a / M48a # 2958555
Pin type face wrench for M48 / T-2 and M4 counter nuts
3 mm screwdriver for M 4 brass adjustment screws
4x hex keys (2.5 / 2.0 / 1.5 / 1.3 mm). The 2.0 mm wrench has a ball head to reach screws even when accessories are mounted by holding the wrench at an angle.
Bottom flange (laterally adjustable 1mm) for off-axis guide or calibration lamp for spectroscopy
Dust cap for bottom flange
2 x M48 dust caps
T-2 dust cap

FlipMirror II (BFM II) Star Diagonal

Product Details

SKU
2458055
EAN Code
4047825042798
Manufacturer
Baader Planetarium
Net weight (kg)
0.24

Mechanical Specifications

Inner Connection (eyepiece/-camera-sided)
M48
S52
Inner Connection (lens sided)
M42 x 0.75 (T-2)
M48
S52
Outer Connection (eyepiece/-camera-sided)
M48

Optical Specifications

Optical Design
Mirror Diagonal
Optical length (mm)
55 mm with S52, 59 mm with M48/T-2

Customer Reviews

4.8

reviews

Tell us what you think about this item!

Top customer reviews

Andreas Heertsch

2024-11-26 01:54:31

I recommend this product

Rating

Flip-Miror anpassen

Tut optisch, was er soll. Mechanisch musste ich einen Zwischenring drucken, um mein 2" Okulartubus befestigen zu können. Beim Anschluss an den Fokusser musste ich die Inbus-Schräubchen etwas nachziehen, da der Flip-Mirror samt Kamera aus der Fassung geraten war.

Einfach zu bedienen.

Mechanik ist, wenn man nicht aufpasst, fragil. s.o.

Martin Weiss

2023-08-29 06:19:54

Rating

Tut was er soll

Der FlipMirror tut was er soll - sogar ein ferngesteuerter Betrieb ist mit "etwas Gebastel" möglich. Passt, kaufe ich gerne wieder!

Bewährte Qualität von Baader

Die Fernsteuerung ist eigentlich nicht vorgesehen, aber es geht ...

VincentvG

2023-03-05 12:19:25

Rating

STRAY LIGHT PROBLEMS ON CELESTRON EDGEHD 9.25 TELESCOPE AND APS-C CAMERA - REPLY

I could not add pictures to the intended reply. So I created a new review with a 5 star rating due to the applied improvement. The reflections on the back of the folding mirror are a serious problem with larger Celestron SC telescopes. I tested the following solutions to cover the back of the mirror: 1. Black printed paper or black photo book paper. This doesn't work very well. Light rays that run almost parallel to the tube surface are still well reflected. First photo. 2. Good optical black paint on the paper back. This helps a lot, but the reflections are still there. Second photo. 3. Optical black painted sandpaper. This works well. Third photo. The cover plate is 30 mm wide and 31 mm long. Additional folded edges, 3mm 45 degrees at the front and 4mm 90 degrees at the rear, increase rigidity, help positioning and prevent reflections on the leading edge. With 2 strips of double-sided adhesive tape of 2-3mm wide, this cover plate can be fixed without damaging the original rear mirror. Prior to assembly I made the cap from No. 60 sandpaper, which was then painted black with slightly diluted Sennelier Mars Black No. 759 Matt (60ml per sachet, available cheaply from art supply stores). See fourth photo.

Response from Baader Planetarium

Thank you very much for those tests and helpful improvements. For those who want to use the BFM II in such constellations like you do, this certainly improves the overall functionality. It's good to see that the BFM II can be upgraded so easy also for this usage

The problem of reflections on the rear of the mirror can be solved

Nothing after the applied improvement

VincentvG

2023-02-26 20:39:20

Rating

Stray light problems on Celestron EdgeHD 9.25 telescope and APS-C camera

This is a very nice product having a lot of options! I'm using it with a Celestron EdgeHD 9.25 telescope. The light path to the camera consists of: - The Celestron telescope adapter 3.29” to 2" male (d=12,7mm) - The Baader T Adapter for SC 2" to M42 male (d=15,5mm) - The Baader flip mirror (d=59mm) - A camera T-2 360° rotator (d=14mm) - A T-Ring adapter for Canon EOS (d=10mm) - A Canon EOS 77D camera with APS-C sensor (d=44mm) The optical path is now 155mm while the target value is 146mm. Unfortunately I found some flip mirror issues: 1. On the mask at the back of the mirror there is some harmless light grey dirt. It should not be there. See picture. 2. The dimensions of the mirror are such that 36x24mm is reflected. That's quit small to cover the inner 38mm of the 42mm tube system. The original Celestron star mirror has no restrictions caused by the mirror size. Luckily the limited Baader mirror size is at the upper port for visual observations. That does not harm to much. 3. In the up position the mirror is quite low in the light path. I expect extra vignetting in the case of a full frame sensor. 4. Most anodized parts are highly reflective in the near IR. So for IR applications some painting needs to be done. 5. Stray light from the rear mirror. This needs to be solved. See pictures. What is the best way to solve the stray light problem? - Another mirror with no reflecting part at the rear? - Adding some black rear cover? - Optical black paint? - Some kind of a mask in front at the input port? - Adding a screw to tilt the mirror from the zero position? Please your advice on the stray light issue.

Response from Baader Planetarium

Thanks for your review as well as your criticism. Please note the following however: The Baader FlipMirror II was designed as an entry level Flip Mirror solution for guiding and visual inspection in mind. While it can serve as a diagonal, it still has limitations compared to a real Diagonals. The mirror in the BFM II already has the largest known size for a flip mirror in the M42/M48 area (at least to our knowledge). Larger mirrors also means larger backfokus which is usually not wanted. We are aware that the BFM II Design leaves some wishes for more functionality and improvements. Given the price of the product we can not implement them all in the BFM II. But we will keep them in mind for future products which could be larger and likely more expensive and therefore leave some room to implement a lot of the things you wished for improvement.

Nice mechanical building quality and a lot of options

The stray light problem and a quite (almost to) small mirror

Markus Mühlenbruch

2023-01-17 13:40:54

Rating

gute Lösung

der Flip mirror II ist eine echte Weiterentwicklung gegenüber dem alten Flip-mirror. wie immer sehr gute Verarbeitung und die Komponenten passen sehr gut zusammen. Der Spiegel wird in einem Gesamtsetup mit Baader Barlowlinse 2x click-look Fokusing holder T2-1 1/4" Okular 7.5 und einer QHY 485 verwandt

präzise gefertigt, typische Baader Qualität, funktional

I wish to create a “planetary train” bot for visual and astrophotography. The OTA is a SCT 9.25 HD connected with a ClickLoc and a 'Nosepiece to 2"/SCTa'. Subsequently, I aim to insert a flip mirror followed by a UFC, and finally the planetary camera at the rear. The entire train will be configured for M48. The distance between the back of the flip mirror and the camera sensor will be 34 mm, comprising a 16 mm UCF, a 6 mm M48 extension tube, and the camera. Questions: - At the top of the flip mirror, I plan to insert an eyepiece (I have a Morpheus 6.5mm). What is the correct length of the light path I need to set on the upper part of the flip mirror to properly house (and focus) the eyepiece? In other words, I want to be able to focus both the camera, whose sensor is 34 mm from the back of the flip mirror, and the eyepiece simultaneously. However, it is unclear to me how the eyepiece behaves concerning its focal point: should I consider the optical length of the eyepiece holder (which should be roughly equal to the 34 mm of the back focal length), or should I consider a different length? - I am aware that I need to house the eyepiece properly with an eyepiece holder that has focusing capabilities. What is the most useful option — or what are the pros and cons based on your experience — between the 1¼" Eyepiece Clamp to T-2i with rotational focusing (# 2458125) and the 1¼" ClickLock® clamp to T-2a (# 2458100)? Thanks in advance for your reply. Best regards

Andrea Manes / August 28, 20251 Answer

At first, thank you for the clear descrition of your problem!

The field stop of the eyepiece must be at the same distance from the flip mirror as the camera sensor, so it is 34mm in your case. With the Morpheus eyepieces (with the exception of the 17.5mm), the fieldstop is at the connection between 1.25" and 2" barrel, so the eyepiece holder needs a length of 34mm - plus/minus a little bit for diopter adjustment.

We would recommend the 1¼" Eyepiece Clamp to T-2i – with rotational focusing # 2458125. It is up to 35.5mm long, so you should easily reach focus and still have about 1 mm left. In case you should need to get a little bit farther away from the flip mirror, you can either use a T-2 Fine-Adjustment ring 1mm (gold) - Aluminium # 2457913 or simply let the eyepiece stick out of the clamp for a Millimeter or so. But it should probably work fine without an extension.

With that eyepiece clamp, you can easily unlock the clamp, rotate it until you are in focus and lock it again.

The Clicklock clamp works a little bit fifferent, as you have to unlock it with the Clicklock, then rotate the small upper ring, and then lock the cicklock ring again. It is of course a personal choice, but for visual, I prefer the non-clicklock version as I can better hold it, while the Clicklock version is my choice for cameras, where I set the focus once and then only lock/unlock the eyepiece, without changing the length of the clamp.
Baader Web Team / August 29, 2025
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MM / July 31, 20241 Answer

Gautam Biswas / March 26, 20241 Answer

I have a Celestron C6, The Badder Flip Mirror II, the Baader OAG, and a ZWO ASI533MC Pro. I cannot figure our, or understand what I need to connect all of this together successfully, and where to measure the back focus for the 533 camera, let alone what the back focus should be. I also cannot figure out where to measure the 55mm back focus for the Flip mirror itself. Very green, new, to this. But for now, I seem to own a lot of expensive paperweights. Pictures or drawings would be a great help!

Michael Webb / December 15, 20231 Answer

Have you seen this article https://www.baader-planetarium.com/en/blog/using-the-flipmirror-the-correct-working-distances/#BFM-OAG where we describe such a setup? The ASI has got a back focus of 17,5mm if you attach it directly to the T-2-thread of the FlipMirror. The FlipMirror adds another 59mm if you use the M48 or T-2-threads. If you attach the FlipMirror to your telescope with Baader Universal Photo-T Adapter C90 for NX4 / ETX with 1¼" filter holder # 2958500, this adds another 24mm; the optimum back focus distance of the C6 is 5 inch (12.7 cm). If you use e.g. Baader Focusing Eyepiece Holder 1¼" / T-2 (T-2 part #08A) # 2458125, this places an eyepiece ca. 30 mm above the FlipMirror, so you should place the camera sensor also ca. 30mm away from the FlipMirror - Baader T-2 / 15 mm Extension Tube #1508154 gives you a distance of 32.5mm, this should work with the ASI and most eyepieces. Unfortunately, there is no standard position for the location of the field stop of an eyepiece, but it is usually close to the connection of the nose piece to the wider part of the eyepiece. You may have to pull the eyepiece a little bit outwards. If you use the Off Axis Guider, you need a T-2-extension to place the ASI at least 24 mm away from the FlipMirror's housing, so if you use the 15mm T-2-extension at the ASI, it should work. But this depends on the back focus of your guiding camera. It is a bit of try-and-error, in the best case, you set ASI plus eyepiece to the same focus, then you focus the guiding camera by mving it up and down and clamping it when you have reached focus.
Baader Web Team / December 18, 2023
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Konstantin / August 24, 20231 Answer

Hello, I have a question about the Baader Flip Mirrors for use on SCTs (Celestron 8SE to be exact). I'm trying to be certain as to which adapters I would need to attach it to the scope, use an eyepiece and attach a ZWO ASI 224MC camera. To connect to the 8SE I believe I need this - Baader Ultra-Short (10mm) SCT Female to T2 Male T-Adapter # SCT-T 2958500B. Correct? What about a ZWO ASI 224MC Camera? Would I have everything I need or would I need some extension tubes? For an eyepiece holder that focuses looks like I need something like this - Baader 1.25"/T-2 Eyepiece Holder with Helical Microfocuser # EYEHOLD-2 2458125. Correct? I don't know if I'll need any T-2 variable / fixed extension tubes. Here's I'm completely clueless. Most likely I would use an eyepiece with crosshairs (SvBony's 20mm or Orion's 12mm). Thanks for the help. I plan to order a flip vendor from Agena Astro as soon as I know all the adapters I would need.

William Battles / August 13, 20231 Answer

For the adaptation to the telescope, you can use Baader SC / HD Ultra Short T-Adaptor, 9mm optical length # 2958500B, yes. The rest is a little bit tricky... The field stop of the eyepiece and the camera sensor should each be in the same distance from the Flip Mirror. The ZWO has got a beack focus of 12,5mm, when using the T2-thread (maybe a mm more with the 1.25"-nosepiece). A standard 1.25" eyepiece usually has got the field stop more or less at the connection between the 1.25" nosepiece and the wider housing. So, for a standard eyepiece, we'd recommend e.g. Camera: Baader Focusing Eyepiece Holder 1¼" / T-2 (T-2 part #08A) # 2458125 - length 29-35,5mm plus 12.5mm for the camera backfocus makes 41,5-48,5mm distance (plus the thickness of the 1.25"-adapter of the camera) Eyepiece: Baader Focusing Eyepiece Holder 1¼" / T-2 (T-2 part #08A) # 2458125 - length 29-35,5mm plus Baader T-2 / 15 mm Extension Tube (T-2 part #25A) #1508154 With these two focusing eyepiece clamps, you should get both eyepiece and camera into the same focus. The problem is that the focus point of a cross hair eyepiece is often different to that of a standard 1.25" eyepiece. So, we need to know the focus difference between the eyepiece(s) and the camera. To find this, you'd have to pint the telescope at the stars or some far away object, focus with the eyepiece and - without refocussing the telescope! - switch to the camera and see if you can find focus by moving it away from the telescope. If this doesn't work, focus the camera with the telescope and then insert the eyepiece and see, if you can reach focus by movint it outwards. Then measure how much you have to move the eyepiece or camera to achieve focus. This is the length of an additional T-2-extension which you need either for eyepiece or camera adaptation to achieve focus. We have some with fixed lengths as well as the VariLocks which can be adjusted: https://www.baader-planetarium.com/en/accessories/adapters-imaging-accessories/extensions-/-focusing-adapters.html?filter_threads_eyepiecesided=2120 (Depending on the distances, you can also screw the camera to the T-2-thread of the Flip Mirror, but for a rather light-weight camera, the focusing eyepiece clamp should be easier to use, especially if you don't want the cemaera permanently attached to the Flip Mirror, or if you want to change it's orientation without using a screw driver)
Baader Web Team / August 14, 2023
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FlipMirror II (BFM II) Star Diagonal

Baader FlipMirror II Star Diagonal

Various ports – variable work

General Function of the FlipMirror II Star Diagonal

Scope of Delivery of the Baader FlipMirror II Star Diagonal:

FlipMirror II (BFM II) Star Diagonal

Product Details

Mechanical Specifications

Optical Specifications

Customer Reviews

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