Seben Laser Pointers Laser Pointers Telescopes Laser Collimator LK1 31.7mm (1.25")

Where to start on a review, I guess the best place is at the start, before actually purchasing this item. I started by looking for some way to make sure I could the image in the finder to be replicated in the viewing lens of the cheap used telescope I have bought to make a start at astronomy. After reading lots of articles that suggest collimation of a Newtonian telescope I naturally looked for a collimator. This is one of the best out of those on Amazon and eBay and seemed to be at a very reasonable price.I proceeded by reading all the reviews for this particular collimator, finding many that thought it was wonderful, a few who were positive it was a good product, but needed checking and recalibrating before use, and others who said it came fully collimated and ready to use. One reviewer did have a lot of negative points and I asked for further details on how he had tested the collimator and how he had actually used it.After getting back a very full and clear answer on the negatives I thought that I could possibly find a way to overcome the negative points, so went ahead and purchased the collimator.Postage was quite quick and the collimator was in a plastic bag inside a padded bubble wrap envelope, which I thought quite spartan packaging for a piece of sensitive equipment, but on opening it I realized that the collimator is a very sturdy piece of equipment.Having read it might need to be checked for correct alignment I had prepared a small turntable and two wooden "V" trestles so that I could line it up with a horizontal line along the kitchen worktop. I had the turntable on a level surface and the line was checked to be totally level on two worktop s at right angles and on the opposite two walls. The collimator was accurate and projected the laser dot dead centre of the line at every point during a 360 degree rotation. The shape of the collimator needed one "V" trestle to be higher, and narrower, than the other to get the light beam to start in a true horizontal beam but after trying the collimator in a few different positions on the trestles the result was the same in each rotation.Now on to use, which was a difficult challenge as my cheap and cheerful scope has a lot of leeway for movement in the eyepiece socket with only two thumbscrews to tighten it in place, which do not hold it in the exact centre. To overcame this I padded the point where a third screw should be and measured the collimator to ensure it was central. My scope was way out, there was no central spot on the primary mirror and the adjustment screws were facing the wrong way to adjust them from behind. Without the collimator this whole process would have been a nightmare, but this is a very good little instrument and I have no hesitation in recommending it to anyone, but I would suggest they buy a better scope than a secondhand cheap model and one that can be adjusted easily.Overall I found that getting the collimator into the eyepiece socket in exactly the right place each time to be a bit difficult but not impossible and the end result has been really good.

This product worked exactly as expected. It was extremely easy to re-collimate asecond hand Newtonian reflector telescope that had been dismantled by the previousowner and also had several screws and springs missing from the primary mirror mount.The focus of the dot of the reflected image on the eyepiece was very good with this telescope (Tasco 302012 d=114mm,f=900mm),but on my original telescope, the celestron astromaster 114(d=114mm,f1=1000mm,f/9, the dot becomes rather large,about5mm in the eyepiece target. (The tasco is 2x the length of the astromaster withabout the same magnification).This I think is due to the higher magnification (andcurvature) of the primary mirror. However this does not appear to affect the abilityto collimate this telescope.What is not mentioned in the advertisment for this product is the very useful feature that the laser output level is adjustable between 7 different brightnesses.A very useful and easy way to collimate a telescope in a few minutes at a verycompetitive price.The product was delivered in the post from Germany in 6 days, which was shorter than expected.

OK, I'm seriously impressed with this. It's so easy to use, my telescope was properly and accurately collimated within about 10 minutes!It's very well made. It feels solid, and not at all flimsy.As other reviewers have recommended, I first checked the collimation of the collimator, in my case by placing it on a windowsill against the window frame, turning it on and gently turning it. No problems, it was delivered properly collimated, and the little red dot stayed stationery as I rotated it.I next put it into the eyepiece holder on my telescope. As another reviewer said, it's very helpful if the centre spot of your primary mirror is marked, and I was pleased to see a very small circle at the centre point of my (Skywatcher) telescope's primary. The red dot from the collimator was way off, at least a centimetre, so I then adjusted the angle of the secondary mirror to centre the dot onto the primary.I then moved to adjust the primary. As you can see from the pictures, the collimator has a cut away in the side, with a 'target' fitted in. You can turn the collimator in the eyepiece holder so you can see this target when you're up at the back end of the telescope. The red dot reflected back from the primary was a little off centre in my case, so I had to adjust the primary mirror to centre the reflection on the collimator target.And that's it. My telescope is collimated, and I can check it whenever I need - certainly whenever I transport my telescope!A very worthwhile purchase. I'd strongly recommend it to anyone with a reflector telescope.

From my perspective you would be way better buying a Cheshire eyepiece instead of attempting to use this laser collimator. The problem like most other reviews state is that the tool just isn't aligned when supplied and once you attempt to align it, it comes out of alignment very easy so you can't really be certain if your scope is really aligned or the tool is just giving inaccurate results. Every time I attempted to use the tool I tried rotating it in the telescope and I found that the laser dot moved around the telescope mirror indicating it was out of alignment or there was too much play in the scope holder. I decided to buy a Cheshire collimator and easily got my scope aligned, I was much more very confident in Cheshire tool since it doesn't suffer from the same Issues.On the positive side the seller did allow me to return the laser without any fuss and did their best to solve the problem.