[barx1963 (Malcolm)]

I have been wearing glasses while observing for some time now. When I had the 8" dob, I found it best to not wear them, probably as with only plossls it was difficult. In my 12" as I used better EP's, I found that images were much the same either way so I did most of my observing with glasses on. The shortest eye relief on any EP was on the 13mm T6 Nagler, which can be done with glasses so all was good.
Last night with the 20" I was having a quick session and when I lined up on Sirius to check finder alignment I noticed a significant "extra" diffraction line that was noticeable brighter than the usual 4 caused by the spider. I was using a 41 Panoptic so I rotated the EP to see if it was a defect in the EP which was negative. Then I tilted my head and voila they moved. So I removed my glasses and the image was instantly better (after refocusing)
I then did some tests, checking with all my EPs and stars and DSO's of varying brightness. Almost across the board the views were markedly better without glasses. The most obvious was in Eta Carina. In my 17mm Ethos at 150x the Homunculus was just a vague blob with glasses on but without I was getting a clearly defined set of 2 lobes showing distinct detail, defined edges and a pointlike star in the centre.
Across the board, stars were sharper and with better colours.

I know I tested similarly with the 12" and didn't see any difference so I just wore them. I guess from now on I will have to get used to taking then on and off. I am really shortsighted so doing anything without glasses is difficult.

Has anyone else found this effect?

Malcolm