Collimation and setting circles

[george7378]

Hi everyone,

I have a 130mm 'scope, and this is the view I get when I point my camera straight down the focuser:

Does this mean that I need to collimate? How would I go about doing this?

Also, I tried using my setting circles last night, and didn't really get the hang of it. I'm confused as to how they work (it is an EQ-2 mount). I think that the silver pointer on the right is supposed to turn, and the wheel is supposed to stay still, but when I rotate the scope, both the pointer and the wheel move. I have managed to make only the pointer move by loosening the locking pin for the RA wheel, but I'm not sure if this is what I do. Are the silver pointer and the wheel supposed to move, while the line between the R and the A points out the right ascension? Here is an image:

Thanks!

[stev74]

Hi George,

I'd recommend having a look at - Astro Babys Guide to Collimation

The tutorial is great and if you follow each step you wont go wrong. Just make sure you don't go making any adjustments until you've checked first that it's out. It may sound like I'm stating the obvious but the temptation can be 'thinking' it's out, making adjustments and making things worse ,when it may be ok in the first place.

As for the setting circles I've never used mine and going by what I've read they aren't very accurate anyway and are more for show. I pretty much find everything by 'star hoping' and would recommend a good RDF like a Telrad to help find your way around the night sky. This thread here should help - http://stargazerslounge.com/beginners-help-advice/105091-setting-circle-help.html

Cheers

[John]

Before starting to adjust things I'd check out the scope with a star test - unless your camera was precisely aligned with the optical axis of the scope when you took the photo, it's not really going to tell you much.

Polaris is a good star to use for this as it does not need to be tracked. If the star test is OK (ie: secondary shadow is more or less central when the star image is defocussed) then things are OK.

I agree with Steve on the setting circles - not really big enough or accurate enough on the EQ2 although I believe one or two members persevere with them.

[george7378]

Thanks for the advice. I generally use my RDF and it (plus Stellarium) has let me find faint fuzzies like the Sombrero Galaxy with relative ease.