Adapting the M68 Tilter for use with T-2 and M48 Accessories

The Baader M68-Tilter (#2458170 , € 255,-)

The M68 system allows for a sturdy and rigid connection of heavy accessories. The M68 tilter is a relatively recent addition to this family of adaptors and was developed to easily compensate for image tilt in an optical train through simple adjustments of three pairs of easily-accessible (even when a camera for example is attached) hex-screws located around the edge of the adaptor. Although the M68 tilter itself is small occupying just 9.50-10.25mm of optical path length, and relatively light weighing in at just under 100g, it can accommodate a heavy accessory payload of up to 5kg. The tilter allows a tilt shift of up to 1° to compensate for misalignments in the image field.

Baader M68 Adapter with M68-Tilter + UFC for the QHY600M camera
Baader M68 adapter with M68-Tilter + UFC for the QHY600M camera.

The M68 tilter has been used successfully on a Celestron EdgeHD 14” with a 36.3MP DSLR and a 61MP CMOS camera to achieve round stars edge-to-edge. A review of the M68 adaptor can be found on AstroGear Today's website.

Other "members" of the Baader tilter-family include the UFC tilter and the FCCT (Filter Changer Camera Tilter) forr RASA 8" and QHY cameras. You can read more about these here.

The T-2 and M48 adaptations for cameras and accessories are still widely popular and we have been often asked whether (and how) the M68 Tilter can be used with these systems. The answer is YES the M68 Tilter can indeed be used with T-2 and M48 accessories and below we show you how. At the moment we have no plans to introduce a smaller T-2 or M48 tilter as the larger size of the M68 unit allows for fine tilt adjustments and also can accommodate a larger accessory payload too.


T-2 Accessories

Lets begin by looking at the T-2 system first. The T-2 system is still widely used and there is a wide variety of cameras having T-2 (female) connections and T-2 (male) fitting accessories.

M68 Tilter with parts for connecting to T-2 telescope and camera-side accessories

Starting from the telescope (left) side and moving (right) towards the camera side, we have the following adaptors in place:

Telescope or accessory with male T-2a thread :->

  • Baader Expansion Ring 2"a/T-2i with 1mm optical path length (T-2 part #28) (#2958242 , € 25,-) :
    The adaptor ring has an internal female T-2i thread (to screw onto the male T-2a thread of the telescope-side accessory) and has a 2"a external male thread. In other words it allows a male T-2a thread to be converted to a 2"a thread.
  • M68 to 2" UNFi Conversion Ring (#2458232 , € 51,-) :
    Has an internal 2"i thread with an M68a external thread. With the above adaptor in place it will now convert the telescope accessory T-2a external thread into a male M68a thread.
  • Baader M68 Conversion Ring (#2458195 , € 41,-) :
    This converts the male M68a thread of the above #2458232 adaptor into a female M68 thread to allow attachment onto the Tilter's telescope-side M68 male thread.
  • Baader M68-Tilter (#2458170 , € 255,-) :
    The M68 Tilter (external M68a thread telescope side ; internal M68i camera side)
  • M68 to T-2 Conversion Ring (#2458233 , € 67,-) :
    This two-piece adaptor steps down from M68 to T-2. The adaptor has external M68a threads to screw into the Tilter's M68i internal threads and has T-2 male threads on the camera side to attach to a T-2 accessory with female T-2 threads (e.g. camera). The adaptor, as whole, consists of two separate parts: M68 to 2" UNFi Conversion Ring (#2458232 , € 51,-) and Baader Adapter 2" (male) / T-2 (male) (#1508035 , € 41,-) .

-> fits to Eyepiece/camera side accessory with female T-2 thread (e.g. camera with female T-2 thread or T-ring)


M48 Accessories

Let us now turn to the M48 system. As with the T-2 outline above, we will once again start from the telescope (left) side and move (right) towards the camera side. You will notice that there are a number of the same parts used as outlined for the T-2 adaptation above.

M68 Tilter with parts for connecting to M48 telescope and camera-side accessories

Telescope or accessory with male M48a thread :->

  • 2"a / M48i Zero-length reducing piece (zero optical length) (#2454834 , € 27,-) :
    This zero-length adaptor has an internal M48i thread and external 2"a SC thread to convert 2"i SC female into M48i female. This will attach onto an M48 accessory with a male M48 thread. As this zero length adaptor is very thin we suggest it be attached to the male M48 accesory first.
  • M68 to 2" UNFi Conversion Ring (#2458232 , € 51,-) :
    Has an internal 2"i thread with an M68a external thread. With the above adaptor in place it will now convert the telescope accessory into a male M68 thread.
  • Baader M68 Conversion Ring (#2458195 , € 41,-) :
    Converts the male M68a thread of the above #2458232 adaptor into a female M68 thread to allow attachment onto the Tilter's telescope-side M68 male thread.
  • Baader M68-Tilter (#2458170 , € 255,-) :
    The Tilter unit - which has an M68 male thread on the telescope side and M68 female thread on the camera side.
  • M68a to M48a Reducing piece (#2458229 , € 51,-) :
    A single-piece step down adaptor with a male M68 thread on the telescope side to screw into the M68's female thread and has a male M48a threads on the camera side to attach to an M48 accessory with female M48i threads.

fits to -> Eyepiece/camera side accessory with female M48-thread (e.g. Camera or M48 adaptor with female M48 thread).

M68 Tilter used with a DSLR and the Baader M68 Quick Changer

It may be that your imaging train uses both M48 and T-2 accessories, for example an M48 male thread accessory on the telescope side and a camera with a T-2 female thread. In this example this is easy to accommodate. Looking at the first T-2 diagram you would simply replace the first (in-line) telescope-side T-2 adaptor (#2958242) for the 2"a / M48i Zero-length reducing piece (zero optical length) (#2454834 , € 27,-) which would attach to the M68-2"UNFi conversion ring (#2458232; used in both configurations) and then use the remainder of the adaptors in the T-2 sequence. If you require to use spacer/extension tubes (e.g. for use with reducers etc) you could select one of the fixed or the variable extension from the M68 series and the Baader M68 Quick Changer to use on the telescope side of the tilter (e.g. see image opposite).

Please note: With the Baader family of tilters, the whole "tilt adjustment operation" can be achieved without imaging train removal. Tilt adjustment is performed using three pairs of opposing set screws, on the tilter's outside edge, which independently move the inner tilt mechanics. These hex screws have tapered and hardened points that bear against a precision hardened ‘zero-clearance’ internal steel-counterpart. The direction that each set screw moves the tilter is shown with a helpful etched arrow next to each individual adjustment screw. You can read more on how to finely adjust tilt with the UFC-, M68- and FCCT-Tilters in an article here.

About the author: Lee Sproats

Lee Sproats

Dr. Lee Sproats has been interested in astronomy since watching Star Wars in 1977 and has appeared on the UK Sky at Night TV programme. He then went on to study Astronomy where he obtained a degree and then a PhD in the subject at University College London/Mullard Space Science Laboratory. He has worked in Australia in radio astronomy and used optical/infrared telescopes on Hawaii and La Palma and Lowell and Kitt Peak observatories in the USA. After working for the University of Surrey to promote the use of computers for teaching in UK higher education and then as an IT trainer for a stock market company, he went on to work for Greenwich Observatory Ltd where he ran their northern branch and then worked for David Hinds Ltd dealing with our and Celestron products. He is often involved in flight excursions that take passengers to observe the northern lights, has led trips to see the great USA 2017 eclipse near Hopkinsville and was lead astronomer onboard a specially chartered 737 to view the 2015 total solar eclipse at 38,000ft. Lee`s astronomical interests include Lunar observing, astrophotography, photometry and pro-am collaborations.

Since David Hinds stopped operation in December 2020, Dr. Sproats works for Baader Planetarium as our UK representative/consultant and is responsible for looking after our UK/Eire dealers, dealing with Baader Planetarium/PlaneWave/10Micron product support, writing articles and also is involved in our large telescope and observatory instrumentation projects.


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