Can't see the primarys three clips using my collimater EP?

[adgecutler]

If you are not bored of me yet I would love some help. I am now sat here trying to collimate, at first I could only see one of the primarys clips upon trying to rectify this I moved the secondary until the primary moved more central (as per manual), trouble is I now cannot see any of the clips to use as a guide. I am using a Cheshire collimater. I have taken the collimating EP out which reveals the clips but fear this is not accurate. What am I doing wrongly?

[Neil1194]

Wind the focusser out with the Cheshire in - I found this revealed the clips round the edge of the primary

[adgecutler]

Thanks Neil but I already tried that and still can't see them.

[spaceboy]

If you have tried both ends of focus travel and still no good I'm thinking the secondary is too close to the primary or it is now square to the focuser ie: perfectly round in view. If you are confident the boxes are ticked on the above it may be you need to adjust the focuser but I would check with others to see what they say first.

[adgecutler]

I have a slightly eliptical view of the secondary.

[philhas]

I find this on my Celestron SLT 130, the clips are not quite visible with a Cheshire.

[adgecutler]

Well I think I am pretty close now, I have all components lined up and just see the clips at the edge of the viewfinder without the Cheshire. It seems that this scope was out a fair bit, I'm sure it could've been done in minutes but as this was my first time it took more like 2 hours. The good thing is that I feel I have learnt a little about my scope.

[spaceboy]

I have a slightly eliptical view of the secondary.

This is your problem then. loosen the secondary screws enough that the secondary can be rotated allowing it to appear circular. You should now see the 3 clips and the views will soon be better for it

[umadog]

How readily you can see the clips depends on the size of the secondary. If it's too small then you won't see the clips. If the sizing is very tight then you will only see all the clips if everything is just so.

[Doc]

A cheshire might not always show the mirror clips, try a collimating cap you should see some of the clip with one of them.

You need to get the secondary to appear as circular as possible as well.

[adgecutler]

I managed to get the secondary to appear nice and round last night and unfortunately still cannot see the clips, it looks as if I will have to make a collimating cap to make any more accurate adjustments. Thanks for the pointers, and now I have actually spent a while "playing" with all the adjustments I feel much happier as I now know how the assembly works. Shouldn't take long to adjust in future with the lessons I learnt last night. Once again thanks to all that have given me pointers.

Jamie.

[terrym2002uk]

Have you tried pulling the Cheshire back in the focuser a little. A cap would be better, which you can make either by drilling a hole in your focuser cap or uses a 35mm film canister.

[adgecutler]

Have you tried pulling the Cheshire back in the focuser a little. A cap would be better, which you can make either by drilling a hole in your focuser cap or uses a 35mm film canister.

Just tried this and still nothing, will have to make a cap.

[umadog]

Take out everything from the focuser and rack it all the way in. Put your eye up to the empty eyepiece and move it around. Is there any one single position from which you can see all of the mirror clips?

If you can't see all the clips then this means that the secondary is a little on the small side. It's no big deal. You don't need to see all the clips. Just make sure you use a sight-tube to centre the primary mirror in the secondary. Once you've done that you can adjust the primary with a cheshire. Usually a cheshire and a sight-tube are integrated into one tool.