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Baader Planetarium laser colli (collimation device for Newtonian and SC telescopes)


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SKU: 18919 Category:


Product can be shipped as of 15.04.2021Order now!

Colli is an abbreviation of collimation. In its broadest sense, the word means adjusting or aligning.

Newtonian reflecting telescopes are usually considered susceptible to de-collimation. And that is true – at least if they are sometimes transported to dark observing sites in the boot of a car. If you are that type of observer, then you should have a Laser Colli™ included in your basic astronomy equipment. With some practice and a little preparation, in just a minute or two the telescope can be once again perfectly collimated.

The technique employed to ensure that a reflecting telescope is properly collimated is, with the Colli inserted in the focuser, to adjust the laser beam so that it reflects back along itself. Of course for the Laser Colli to function accurately here, the laser beam must be exactly centred in its housing to start with. The laser is co-axially adjustable at 6 points within its housing (this adjustment has already been done by us in-house). Six small screws are used for this, so please do not adjust these – the laser will immediately become tilted in its housing and collimation is then impossible.

What distinguishes the – specially manufactured for Baader Planetarium – laser adjuster compared to the various competitors? The really clever thing here is its special etched reference plate which no other laser collimator available on the market has. Firstly, it is used to make the reflected laser light beam more easily visible – a simple glass plate here would make the point of laser light much more difficult to see. Secondly, in the case where the telescope is badly de-collimated (so the laser beam is not even reflected back onto the plate), it allows you to look through the plate into the focuser tube itself to see roughly in what direction the beam has been reflected. A grazing reflection will be visible somewhere inside the focuser tube.

Additional advantages of our Laser Colli:

  • all-metal design
  • extremely accurate 1.25″ barrel
  • laser beam exits through a 0.8mm aperture, making it also suitable for collimating SC telescopes


Never look directly into the laser beam. Protect your eyes. Store the laser-Colli™ so that it is not accessible to inexperienced adults or children. Bear in mind that, in a badly de-collimated telescope, the laser beam could be deflected out of the tube.

The white point-shaped marker (reference point for adjustment) should be in line with the clamping screw on the focuser.

Collimation always begins with checking and setting the secondary mirror. For this, it is a big advantage if the centre of the primary mirror has been marked.

When you can see an image on the cross-mark etched reference plate, keep adjusting the primary mirror until the reflected beam falls through the central hole and is reflected back on itself.

Product number: 18919


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