Is there a law of diminishing returns on eyepieces?

[Moonshane]

Not sure why they are designed this way, but using Binoviewers, I see it as an advantage as I find most TV eyepieces focus further out than others. This is not a big issue on the moon (as I use a T2 prism diagonal)  but certainly is with solar as I use a 2" wedge and a pst mod.

[JOC]

So on the subject of EP's - if I want to fill more of the useable EP view with Jupiter (assuming the clouds ever clear again) and I own a 10mm EP am I better off getting a x2 converter or a 5mm EP (leave aside that I can use the converter with other EP's - I'm just looking for the potentially best view) or is 5mm too much for my telescope.  I think I'm not going to get many views of Jupiter (given current weather phenomenon) and s I want any view to be as apparently big in the EP and as clear as it can be given any current atmospheric conditions - what should I buy please?

[Louis D]

2 hours ago, JOC said:

So on the subject of EP's - if I want to fill more of the useable EP view with Jupiter (assuming the clouds ever clear again) and I own a 10mm EP am I better off getting a x2 converter or a 5mm EP (leave aside that I can use the converter with other EP's - I'm just looking for the potentially best view) or is 5mm too much for my telescope.  I think I'm not going to get many views of Jupiter (given current weather phenomenon) and s I want any view to be as apparently big in the EP and as clear as it can be given any current atmospheric conditions - what should I buy please?

I've been getting good views of globular clusters with my nearly 20 year old 5.2mm Pentax XL in 8" dob.  My 3.5mm Pentax XW is generally too much as the exit pupil becomes too small and I can't see past my floaters.

For Jupiter, I generally do better at 100x to 125x.  Above that, low contrast features blur together.  In a big dob, it's easy to go to 200x or even 300x and retain low contrast features under the same atmospheric conditions.  I've never figured out why I do better at lower powers on low contrast objects in the dob but do fine on high contrast features at high powers.  Do the obstructions (secondary and spider) really play that much havoc with the light rays?

By comparison, Jupiter looks way contrastier in my little AT-72ED at 100x than it does in the 8" dob at 200x despite having a smaller exit pupil in the refractor.  Makes me think I might want to get a 6 inch APO for planets someday.