Wearing glasses while observing?

[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

[niko]

Malcolm,

I haven't experienced this as a glasses wearer but am able to identify your problem and the solution.

You and your eyes are best suited to dobs at or below 12".

I therefore strongly advise you gifting me your 20" and sticking with the 12"

niko

[Barrykgerdes]

I normally view with my glasses off. Mainly it is more convenient. I am only slightly myopic. I have never noticed the effect you mention but it sounds like some possible internal reflection in the glasses. As you say you are profoundly myopic I would suspect that your glasses are quite thick, particularly at the edges.

Usually you will require a small change in focus to compensate for correction caused by the glasses. When I am at astronomy nights I always focus with the glasses on. That way the scope does not need refocusing for the average viewer.

Barry

PS Some expert say that myopia is a sign of superior intelligence,

[barx1963 (Malcolm)]

Thanks for the replies.
Barry your reply got me thinking. When I observe i turn my head slightly to the left (I use my right eye) I think so I have my nose well away from the eyepiece, so I am looking through a thicker part of my glasses. That may be contributing to the diffraction effect.
I also reflected that the effect was most noticeable with brighter stars. implying that the 20" makes this even more noticeable.

Niko
I'll gift you a look through it at SV in March!
BTW I have sent a PM

Malcolm

[leon]

I too always found it easier and better without the specs on.

Leon