Secondary collimation

[Uranium235]

If you are having to adjust the secondary every time you use the telescope (assuming its not been bashed about), then something is clearly wrong. Mine gets touched only 3-4 times a year, and thats only in order to slightly improve field illumination.

My hunch is that it "appears" your secondary collimation has drifted because of the random nature to which your collimating device attatches to the focuser. Take it out, put it back in, and you may find you dont hit the same spot twice. A self centreing adaptor helps with this aspect because the connection is (more) repeatable, and if you have a purely threaded connection - then the collimation device is in the same spot 100% of the time. Having said that, the chances of a visual observer having a threaded connection is rather slim (I never look through mine, imaging only), so the best bet is the self centreing adaptor.

In the absence of a self centreing adaptor, I would repeatedly insert and remove the collimation device to check that you havent collimated on a duff connection.

[malc-c]

Collimation is one of the most frequienly discussed topics, and there are lots of posts covering the basics so I won't repeat them here.  For me the most useful tool to have is a self-centering adapter.  You can have the most precise factory set, guaranteed for life not to need re-collimating colimator, but use it with a normal set of thumbscrews will always cause descrpencies as the screws push the laser out of true alignment.  I use a Hotech laser collimator which is itself self centering, and this combined with a self centering adapter means the laser is always central and true to the focuser.

[Jason D]

I use Glatter parallizer. It is high quality and ensures parallelism between the eyepieces and focuser axes. Technically, parallelism is what is important -- not self-centering. 

http://www.firstlightoptics.com/adapters/howie-glatter-parallizer.html

Jason