Collimation without a collimating tool

[earth titan]

Skywatcher 150p. Love it. However the images of planets are a little fuzzy on higher magnification - in particular Saturn through a 6.3mm Plossl and especially with the 2x Barlow.

I know the moon is very bright at the moment and consequently the viweing is not as good as it could be but I am starting to check the collimation using Astro Babes excellent guide. Just to ensure everything is as good as it can be.

Happy with aligning the secondary and using a home made colllimation cap but as I have spent a fair bit on scope, equipment etc. and would prefer alternatives to Cheshire collimaters if they are available until I can scrape the cash together. Any suggestions? Any other excellent guides?

[acey]

Yes, you can collimate without any tools. Just use a star. Look at one out-of-focus at high power, see if the "donut" has its dark spot exactly centred. if it does (and the star is centred) you're in collimation. If not, move the star around in the field and find if you can get its dark spot centred in the donut. If you can't, you're either way, way out, or your optics have inherent coma. More likely is that you'll find a "sweet spot" where the coma disappears. By adjusting the collimation bolts you want to move that sweet spot to the centre of field.

Otherwise, if you don't want to spend money on a Cheshire, you could try making one.

accessories

And don't worry if planets look a bit blurry through a 6.3mm plossl plus Barlow. They'd prbably look blurry with that combo in my 12" too.

[sgazer]

hi,

with that combination of eyepiece and 2x barlow you'll be up to about 240x magnification, which is pushing the usable limit in this country and would require excellent seeing. Your scopes potential is about 300x, again with excellent seeing, collimation and eyepieces. It's better to have a lower magnification clear image than a high mag blurred one.

The moon shouldn't affect the seeing on planets, as they are bright, but any atmospheric distubances or cloud etc will. If you look for long enough, their may be occasional moments of clarity with the image.