Collimation

[Moonshane]

I often struggle with a star test for a couple of reasons. I find it difficult to be sure that the star (I usually use Polaris) is absolutely central which is essential for star testing. Furthermore I find that seeing usually prevents achieving the magnifications I need to see the star pattern properly and I cannot make sense of the boiling patterns. Maybe I am doing it wrong but the view seems good enough to me so I am happy.

This is the main point I feel. If you collimate and can see good detail, contrast and sharpness then what is there to be worrying about!?

[kniclander]

That's a good point Moonshane. the "received wisdom" seems to be that a star test is the ultimate test but surely it's possible to assess things much more accurately by looking down the cheshire etc than by trying to assess whether a de-focussed star is perfectly round?

[LeeB]

Agree I collim. for ages with just a cap and an eye. Recently purchased a cheshire to check my eye and was spot on. likewise with lasers once they themselves were collied. When i now collim lasers I use my scope as a first point of reference and then tweak with long range rotation method against a scale. I have not yet tested any laser that straight out of the box (and that includes some v expensive ones) is as good as my eye, cap, cheshire collimated telescope.

The big thing to remember is if you are careful and take your time the first few times it soon becomes second nature.

[umadog]

I think that the star test is the final "sanity check" that your collimation procedure is right. Once you've established this then you don't need to do it again. In future, you just use the tools. Once you know how to read them, collimation tools provide a lot of information and tell you what to tweak. I think this is a lot less clear when star-testing.

In fact, I don't think a star test is a very good way to collimate a scope. There are two reasons for this. Firstly, the test star has to be exactly in the field centre. Without a cross-hair eyepiece (which most people don't have) judging whether the rings circles are concentric isn't easy. Secondly, if the seeing is poor then performing a star test is hard. In contrast, an accurate collimation tool always produces clear images. I find an auto-collimator is more sensitive to misalignment than a star test.

[cotterless45]

Once you have tight collimation , it should hold. I've transported the Lightbridge several times in pieces, it's held tight collimation.

[fountain]

After a year mine has just gone out. Although I have made my own I probably don't have enough experience to use it properly, so I'm going to get a tool.

Cheshire the best?