Secondary slightly desilvered around edges :(

[BrendanC]

So, after nearly crying the hot tears of a child to collimate this darned thing yet again, in the process I noticed that the silvering around the edge of the secondary seems to have been worn away in small patches.

I may have left the OTA out one night too many, although kept snug with all the cap covers on, hats over them, and inner and outer of a serious tent covering the whole thing.

I guess it's dew? In which case, can that, do this?

If so, given that I'm currently getting OK results with it, do I need to worry? I bring the OTA in now, so it shouldn't get worse. But I do know that whereas artefacts on the primary aren't too much of a concern, on the secondary, they are.

Any/all comments welcome other than 'Just give up Brendan, it's not worth it'.

Thanks. 

Edited December 15, 2020 by BrendanC

[malc-c]

Most SW secondaries have flat unsilvered areas at the edge on the minor axis, possibly due to where they are held in the silvering process.  It's more of an issue when imaging with non PDS versions as the problem causes stars to have additional spikes (I'm speaking from personal experience).  On a PDS the issue shouldn't cause any such problems, and if you are getting good results then no need to worry

Edited December 15, 2020 by malc-c

[BrendanC]

Thanks. It's kind of rough around the edges which it definitely wasn't a while ago. But, as you say, it's working ok so I'm going to leave it!