Help! Scratched primary mirror on setup

[histronaut]

Jeez.....well......this is how I start off my time on the forum I guess......

I just bought a 10'' Dobsonian telescope, and put it together tonight, but as I was opening the lid....I did so incorrectly and the lid fell through the scope and hit the mirror

I attached the image, it's brand freaking new mirror other than that spot right in the middle of it.

PLEASE tell me I don't need to have it replaced to work nearly as good as new, I've been dying to own a telescope and that would be a huge bummer!

Thanks for your time guys!

[Robh]

I don't get how the lid would have got past the spider vanes. Is it a truss scope? Any scratches near the primary centre would be under the secondary mirror and would return no light to the secondary anyway. I have several scratches and dirty specks on my primary. It seems to work just fine.

Regards, Rob

[histronaut]

Thanks for the reply! I was dumb and unscrewed the spider vanes...caught the vanes/secondary mirror before it fell and really lucked out....had another individual tell me the same thing, that the mark is close enough to the center (similar to the target at dead center) that it will be blocked.......wipes brow :)

[leon]

It will be fine. the scratch being in that area will have little to no effect at all.

Leon

[dannat]

Have a look thru it , should be fine, if you want colour in the scratch with black texta

[erick]

Errrr.... Yes. That was a bit too much fiddling with your new scope. :doh:

Put a small bandaid on it :D Looks like you are well in the secondary "shadow" area - no effect on your view.

[Forgey]

I have a much larger scratch on my 6" primary and my secondary mirror is chipped, look here http://www.iceinspace.com.au/forum/showthread.php?t=85561 and i still get great views of the planets and nebula so far with no loss of quality. I covered the chips in the secondary mirror with black texta.

[RobF]

Have you had any practice collimating newts? If you've taken the whole vane assembly out you'll be fiddling a bit to get things centred and collimated probably. Will potentially affect views lots more than scratch if not set up optimally. Then again, pulling to down is good practice for understanding how to set it up again. Plenty here to help if any trouble.

[ausastronomer]

Hi,

That's the best thing to do. It's likely, as others have mentioned, the scratch will be in the secondary shadow path and have no effect. However, it can't hurt to paint out the scratch with black texta. This is the best way to treat a scratch that is in the light path. The scratch will generally only cause problems because of the additional light scatter it will cause. If you "black out" the scratch it can't scatter much light at all.

Cheers,
John B

[supernova1965]

Well this is my 10 inch Dob and if you check out this thread the second post you will see what it looks like you have nothing to worry about. I bought this one second hand for $50 and I get great views still from it.

http://www.iceinspace.com.au/forum/showthread.php?t=55796

[andyc]

You should be fine! My primary mirror on my old 8" Dob was literally speckled with lichens up to 1cm across, and almost transparent in places for a while, after it sat in a garage for a decade. I cleaned it up, and was still able to get stunning views of faint nebulae (e.g. the Veil) and galaxies, even though the mirror appeared a mess to look at. The main point being that you'd be surprised how poor a state your mirror can get into before image quality degrades a lot. I'd not recommend being as negligent with your mirror as I was, however, but a small scratch or two should be no problem!

[Jen]

Oh i feel your pain i joined IIS a few years ago when my hubby dropped my 2 week old scope and put a big dent in my tube :(
I have seen worse mirrors than that so u should be fine ;)
:welcome::welcome: to IIS cheers :D

[Scopie]

I just bought a dob with a dent in the side - new - at a discount. Nice thing about dobs is it would have to be a helluva dent for you to not be able to collimate it out!

[CometGuy]

The McDonald observatory 107" telescope was the unfortunate recipient of several handgun shots. See here:

http://toyfj40.freeshell.org/McD107Wound.jpg

They simply blacked over the craters left by the bullets and the telescopes performance is hardly effected.

Hope this puts your scratch into perspective!

Terry