Cheshire Collimator Cwestion :-)

[Daedalus]

Got my Cheshire Collimator today. No instructions...so i guessed. I placed the collimator into the focuser and when I looked into the cross hairs, what ever I was looking at didnt look lined up. So I twiddled each of the adjustment screws on the bottom of the scope till it did. Then tightened up the screws that secure the mirror.

Is that all there is too it? not had time to test it cause of the rain! But it just seemed too easy.

[Telrad]

Practically. Try Astrobaby's Guide To Collimation:

Astro Babys Guide to Collimation

or this one http://www.propermotion.com/jwreed/ATM/Collimate/Chesire.htm

This one is excellent too: http://www.andysshotglass.com/Collimating.html

all really concise & good

[Moonshane]

hi there

there are a number of steps to 'perfect' collimation although this is rarely possible.

1) ensure the secondary is central in the tube

2) ensure the focuser is vertical and central on the tube

3) ensure the secondary is central in the focuser

4) ensure that the secondary is aligned with the primary

5) ensure the primary is aligned with the secondary

you may need to repeat steps four and five a couple of times to get it right but thankfully you only really have to do step 5) regularly but you check points 3)-5) each time you observe. you may not need to change anything but always check - it's a good habit to get into and will ensure you get the most from your scope.

in truth, it is highly likely that your secondary is central in the tube and that your focuser is correctly fitted/adjusted (steps 1) and 2) so don't worry about these for now.

for point 3) make a collimation cap which allows you to see the whole of the secondary and the ring at the end of the focuser. you may need to turn the secondary or move it down the tube a bit but again unlikely, this is almost certainly going to be OK too like 1) and 2). check the secondary (shiny part) looks round and central down the focuser with just your naked eye for now.

for point 4) put in the Cheshire. Assuming you have a centre circle/donut on your primary, adjust the secondary grub screws until the cross hairs on the Cheshire are central with the donut. the secondary is now aligned. ignore the spider vanes, these may or may not align with the Cheshire cross hairs.

then using the Cheshire, adjust the primary until the black dot is inside the donut.

you are then collimated. sounds more complex than it is and you'll get the hang of it soon enough. try this guide which has helped many before Astro Babys Guide to Collimation

not sure where you are but if anywhere near Manchester, I'd happily help.

[Daedalus]

Cheers. Just checking that guide out. I remember seeing this once before, but it should make more sense now I got all the right parts. :-)

[umadog]

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