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Originally Posted by bluesilver
I thought the larger aperture would give me more detail due to the more light it lets in.
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In theory resolution is a function of aperture. But turbulence in the atmosphere limits that, most of the time.
The second challenge is the quality of the optics. There is a distinct difference in what you will see though a scope that has what I can only describe as "ordinary" (ie budget grade) optics vs one that has premium optics, certified and tested to meet a very high standard.
The third challenge is how you propose to achieve high magnification. Using a fast (ie short) newtonian and insanely short eyepieces with 10 elements is not the optimum solution.
It is far better to start with a scope with a long focal length and use a more modest eyepiece with as few elements as possible. Ideally, 1 element (they exist but have a small field of view, around 10 degrees).
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instead of looking at say the 10 inch dobsonian i might be better of going for something like the Cassegrain Telescopes, Something like the Black Diamond 180/2700 Mak-Cassegrain, where it has a focal length of 2700 mm ?
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That would be a good start for a budget portable scope, optically they are consistently very good and better than the average 8" SCT. They're a very nice size/weight too for a "quick look". The sheer weight of larger SCT's like C9.25 and C11 (and especially the CPC versions) or 12" LX200 makes them tiresome and many give up as they just can't face packing that up in the dark and in the cold. The Meade 14"/16" and C14 are not one-man portable scopes.
In this respect at 13kg the MK91 is a very good solution, as is a C9.25 on a GEM mount. (not the CPC version).
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Or this might be a tad over the top, but the Celestron C14
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I wouldn't be interested in a C14 even if you gave it to me. My next choice would be something like a lightweight truss 14" f/7 dobsonian with a Zambuto mirror, small secondary, and properly baffled. The snag is the wait time for the mirror as it would have to be made to order, and Zambuto have a very long backlog.
If money is no limit there is a 16" f/15 Maksutov for sale with 1/8 wave optics that will easily out-resolve anything from Celestron/Meade. But that is a tad under 50,000 euros.
FWIW on the planets my MK91 out-resolves all the 10-11" scopes it has been compared with, in side-by-side comparisons on the observing field. C9.25 and Meade 10" aren't even close. In theory something like a 12" f/8 newtonian with a perfect mirror and small secondary should be better, but it would need a Zambuto mirror and will be a fair bit larger. That's in theory, practice is another thing and I have yet to see one.
The one scope that I do know was better is the 16" f/7 newtonian at Crago (Mt Bowen). But that had a very high quality Suchting mirror and the scope is a big beast, with a full tube and permanently mounted in an observatory.