Hi Ben, I'll speak from my own experience going from a 6" to a 10".
Jupiter in a 6":
In a 10mm: Both the NEQ & SEQ red bands could be made out, the planet was small, and the red spot was faint and just visible.
Barlowed to 5mm: bit larger, image not as detailed/sharp (and the red actually looked redder through a 10mm).
Saturn in a 6":
By the time Saturn came around later in the year, I worked out that a 7mm hit the sweet spot better on planets. Barlowing a 15mm wide angle ep down to 7mm, the planet was mostly always beautiful and sharp. The black Cassini division could easily be made out, and the black ring closest to the planet (the D ring) surprisingly could always be made out (even by my hubby and daughter).
In a 4mm, I once saw the faint shadings of the bands on Saturn. It appeared very large and filled up the entire field of view of a standard Celestron 4mm plossel. Constantly nudging the dob proved too much work while trying to see detail with such a tiny field of view- it was incredibly frustrating.
The biggest difference I noted for planetary viewing on both a 6" and 10" was that I could see planets almost all of the time successfully on a 6", whereas a 10", even with a 10mm ep, I had trouble getting "great" (not fantastic) views on a regular basis. Yes, there was definitely more resolution using a 10", but the viewing times had definitely decreased. I soon came to learn first hand what others have said, that larger apertures tend to magnify poor seeing conditions. In my opinion though, I would rather see a planet which gives me some detail to chew on for say 5 times for that season, than having a planet I can see all the time with little detail.
Jupiter in a 10":
This is now the next Jupiter season to my notes above and have since purchased a premium eye piece, being a Pentax XW.
In a Pentax XW10mm: The planet is now slightly bigger. I honestly don't know if it has anything to do with the size of the apperture or whether the fact that Jupiter is actually closer to us this time around. Some input from others, size vs aperture would also be a help to me as well.
The planet was definitely brighter, the red bands were striking.
I could easily make out little cloud formations and the narrower red bands both in the north and south. The ripples of blue/grey clouds were jaw dropping as they were sharp and detailed.
Interestingly, when I threw on the 6.7mm Meade 5000 (it was a night of relatively good seeing that this focal length should have handled nicely), however, the ep made Jupiter very bright, washed it out and very little detail was discernible. I then changed to a Celestron 4mm which gave me much better contrast and resolution compared to the Meade.
Case in point: a good quality ep will show you a lot more.
There are factors which will dictate how well you see a planet: aperture/quality of eye pieces/ seeing conditions/ how well your eyes are trained at teasing out detail (the more you do the more you'll see).
I can't comment on a view through my 15mm barlowed down to 7mm (as I'd used on Saturn), as this ep is now rendered useless on my scope due to the fast ratio of the 10' dob- it gave me fuzzy images, and sea gulls every time I used it. Perhaps seeing conditions played a part too, I don't know, I just know I could never use it - on anything really.
Ben, for a much detailed explanation, have a look at the link I have supplied below which is my first Observation Report (posted) using my 10" dob. giving some comparisons from my 6" to the 10". In particular read about the sections on Jupiter and the Orion Nebula.
Please note that within this report I made reference to having problems with a 6mm TMB. I put down the performance that night to poor seeing conditions, however this actually proved not to be the case in my future sessions using the TMB. Since the report was done, I had many attempts trying to use it and did comparisons with other ep's, the TMB just would not come into focus on my dob, so it was rendered useless. Though others here have used it to great success and satisfaction. At the time of the report I thought that perhaps the seeing played a part on it's performance, but it wasn't to be the case.
http://www.iceinspace.com.au/forum/s...ad.php?t=67200
I have come to understand why making notes of observations is so important. It is interesting watching my progression on discerning detail on objects past to present as my eyes improve.
A quick little story...
When I was looking through Ron's (astroron) 16" scope (monster much?!
) he lined up NGC 104 (47 Tuc) for me. He told me to have a look and tell him what I could see.
Not knowing what to look at
, I nervously starting looking so my answer would be correct
. With confidence and a smile of satisfaction on my face, I responded back with "there's a break in the core". Phew, correct answer- was I relieved..
. If he'd asked me that same question 12 months I ago I would have said, "yes yes I see a shiny bright ball"
Ron is a great teacher. He did right by getting me to work it out for myself rather than telling me, with his guidance, pushing my new and slowly acquired observing skills.
Observation Reports are also very handy to check on things - my post here is probably a good example as I had to refer back to them.
You should join us in the Observing Forum and try your hand at reporting, we would love to have you there!
I hope my my post has been of some help to you.
Blimey, I've just done a preview post to what I've written, and for pete's sake, I do waffle on don't I?!
My wrists now ache
If I don't post anymore today, it's your fault Ben.