I think we all agree that seeing is the dominant factor. However, what if on your night of excellent seeing you had used a better or higher quality planetary eyepiece?
Seeing will vary but the quality of your optics is fixed. Better optics will always be better and worse optics will always be worse, in any type of seeing.
Well what is the better planetary eyepiece? Supposedly it is the 3 and 4 element orthos etc. So I would need a 7mm ortho to meet the “planetary” designation.
So lets think about that:
~Poor eye relief - which is uncomfortable and a distraction
~Small AFOV - which means more frequent recentering of the planet since I use manual alt-azimuth
~Possibly scattered light issues because for all the praise of orthos I’ve typically been disappointed with their control of scattered light and their contrast. That includes older University orthos, the HD orthos, and the currently available Japanese orthos that I’ve tried.
vs the 7mm APM XWA
~super comfortable eye relief
~no issue with scattered light last night
I think it highly likely that I am not going to see more with a planetary ortho than I did last night with the 7mm APM. I was able to relax with the comfortable view and did not have to adjust the slow motion controls every 2 seconds.
At this point, with on axis viewing, I’m not convinced that low element count eyepieces are any better than high element count eyepieces. For example, while I love the 4 element 32mm University Konig in my 102mm f/11 ED, there is no question that the 9 element 30mm APM UFF provides sharper star images in the central field.
Obviously there are some rarefied options like the 5.1mm Pentax XO, Zeiss orthos that probably give you a detectable advantage if you don’t mind cramming the eye lense into your retina.
Edited by russell23, 31 July 2021 - 04:06 PM.