GSO 10" DOB mirror blues

viking88 · #1 29-08-2008, 08:43 PM

I just got a "new" secondhand 10" GSO DOB. The guy sold it after having it for only 2 months. After inspecting the primary mirror I found it looks like it is "chiped" on 2 places on the side of the mirror. The cips extend about 2 mm into the inside of the mirrors reflective surface.The one chip luckely fits under one of the mirror clips.

Does anybody else have chips like this and should I wory about it? If it is a bad thing where can I get a replacemnet mirror and what are the specs? 254mm 1270mm focal length(f5) OR 254mm 1200mm(f4.7)? Is there a way to measure it?

AdrianF (Adrian) · #2 29-08-2008, 08:51 PM

My 10" GSO also have chips around the edge. Doesnt appear to affect anything.

Adrian

Solanum · #3 29-08-2008, 09:32 PM

Mine too, about the same distance in as the clips (I suspect there may be a correlation there...). If you can't see the clips whilst viewing I don't see why you'll see the chips.

iceman (Mike) · #4 30-08-2008, 06:42 AM

Chips right on the edge won't affect your viewing at all.

It's possible that the chips originated from someone trying to tighten up the mirror clips too tight. In fact the mirror clips should be loose - loose enough that they just hold the mirror in place but isn't putting any pressure on the mirror itself.

If the clips are tight, not only do you risk chipping the mirror, but you introduce astigmatism as you squeeze the mirror out of its ideal shape.

btw

to IIS!

GrahamL · #5 30-08-2008, 08:40 AM

mine had a couple of small ones to.. I thought it might of happened when they beveled the edge as one was hidden under the mirror clip so it
seems it was there when they put the mirror in its cell.

It'll be fine .. A new mirror may well show you the same small defects
enjoy your new scope and welcome to IIS

CoombellKid · #6 30-08-2008, 10:30 AM

Out of curiousity

What are the clips made out of? do they have any protective rubber or
such on them?

regards,CS

Solanum · #7 30-08-2008, 01:31 PM

Mine are metal (from memory), they definitely have rubber pads.

Starkler (Geoff) · #8 30-08-2008, 01:51 PM

I certainly wouldnt be rushing out to replace the mirror as you wont see any visible difference in the views.

GeoffW1 (Geoff) · #9 30-08-2008, 05:33 PM

Quote:

Originally Posted by viking88

I just got a "new" secondhand 10" GSO DOB. Does anybody else have chips like this

As below, don't stress. I bought a good 300mm GSO here in IIS with some edge defects, and it does not affect the seeing at all. Enjoy.

Cheers

rmcpb (Rob) · #10 30-08-2008, 05:34 PM

If it really worries you, you could blacken the edges of the chips but I wouldn't worry considering the location and how shallow they are. Just enjoy the scope, they will make noooooo difference.

viking88 · #11 30-08-2008, 10:30 PM

I must say the IIS forums are "alive". So many replies in such a short time! Thanks everybody, I feel much more at ease and now I will REALLY enjoy my scope!

tnott · #12 01-09-2008, 07:24 PM

You will not notice any effect of the chips at all. Shine a torch down the tube of any commercial SCT and you will see what I mean, scratches everywhere! I know a couple of people with huge chunks knocked out of their mirrors but they have long since gotten over it as it makes almost no difference. Tiny effect compared to the secondary obstruction.