ring image on corrector glass of 8SE

[bomberbaz]

I have found a image on the corrector of the 8SE I have. Its quite faint and doesn't efffect the viewing. It appears to be on the inside of the glass surrounding the secondary. I have only just noticed it and wondered if anyone can shed any light as to what it might be.

[Stargazer33]

Looks a little like a calcite ring mark from evaporating water. Do you bring all your kit indoors after a session and leave the scope standing on its front cover? Mind you that would mean a lot of dew getting INSIDE the OTA for that to happen and I don't think dew contains calcite!!! (I live in a hard water area).

Either that or a rub mark from the retaining collar being screwed onto the secondary mirror assembly and someone not being very careful about touching the corrector plate whilst doing so.

[bomberbaz]

Is it removeable nd is it a manufacturing error? if it is I could have it looked at as it about 9 months old. I mean it doesn't effect the viewing but is it something that can be corrected.

It is not something I have done but I want it righting as you would.

[Stargazer33]

You can take the secondary out on the 'Fastar' systems. I did mine a little while ago to remove some swarf that had got onto the secondary mirror. Then I found out that the retaining collar isn't fixed to the corrector plate and so I couldn't screw the secondary back on without removing the corrector plate too!

I then worried about whether I had flipped the corrector plate before I put it back on! If you do decide to remove the corrector to try to clean it, mark the tube and the corrector (low tack tape is a good option) so that you get it all back in the same postion/orientation. Be careful what you clean the corrector with too. You don't want to scratch it and make it 10 times worse.

You would obviously have to recollimate afterwards.

I think most people on here would say, 'if it isn't causing you any problems then it's best to leave it alone'.