help cleaning my reflector

[johnkirkpatrick]

my astromaster 130eq-dm has a bit of dust on the large mirror at the base of the scope. am worried i would have to collimate it if removed, as i have no tools to collimate.?

[pvaz]

You'll have to collimate. Just a bit of dust is normal and you should leave it be as the difference is minimal. The only effect is you loose that tiny bit of aperture where the dust is blocking the mirror. To test this, try to put your hand in front of the telescope blocking about half of the aperture, while observing. Things will look fainter but you still see them.

However you should learn to collimate as it makes a lot of difference regarding sharpness and contrast, specially on a f/5 like yours which is much sensitive to bad collimation.

If you do decide to clean use a proper lens cleaning kit (cloth and liquid). If you happen to scratch the coatings while cleaning it will probably ruin the scope.

[johnkirkpatrick]

can collimation be done indoors without a tool? if so i would practice now.

[pvaz]

Yes it can be done indoors. In fact I always do it indoors.

You need at least a collimation cap. You can make one at home. Use a photographic roll plastic case (it's 1,25" wide) make a 2 mm hole in the center then put it on the focuser as if it was an EP.

Then follow the steps on this guide where it explains collimation with a cap:

Astro Babys Guide to Collimation

A Cheshire or a laser colli will make it easier. If the secondary seams centered then don't touch it as it's the "hard" part. Align only the primary then do a star test outside to check results.