Barlow & Cheshire suprise!

[slice of heaven]

The cheshire is basically a sight tube fitted with cross hairs.
Looking into the sight tube you can see the line up of the optics.
eg. the bottom of the focuser,the secondary mirror,the primary mirror and the reflections of those. Line all these up and your sweet. The crosshairs show you the centre point of the focuser compared to the optics and their reflections.

Easy hey!

For 90-95% of collimation it's great. Getting the last 5-10% thats the tricky bit.

Slice

[ballaratdragons (Ken)]

and because my mirror is centre spotted with a hole in the centre, when it is collimated I can see the tiny hole in the EP in the centre of the Mirrors centre spot.

Below is what I see in my Cheshire when collimated.

[h0ughy (David)]

thanks guys, helped fill in some blank spots. Although I don't know how it would work with the SCT.