Axunator, what are you really trying to do ? Are you actually a visual observer, or an imaging type ?
IMHO there is a decision to be made - if you live in a big city and want to observe, the only realistic targets are moon, planets, the usual bright clusters, and making measures of double/multiple and variable stars.
For this, yes, a long focal length scope is ideal - and you already have a C9.25. The Mewlon will not beat it on these because aperture rules, assuming the optics of the C9.25 are good (which might not be valid). The Tak simply isn't in the running for this, its aperture is not enough to challenge the Mewlon or the C9.25 and its focal length is not sufficient either for seriously high powers (by this I mean 400X - 700X). Visually, with my Santel 100X is merely for locating targets, and the fun begins at 200X (average seeing) and in excellent seeing 700X is useful.
If you have the opportunity to visit a decent dark sky site to observe DSO's, likewise aperture is king and the C9.25 at its lowest power will simply slay both the Mewlon and the Tak.
The exception to this is imaging where the small Tak is a better match to most cameras for DSOs, whereas the C9.25 is the better match for planetary imaging. Personally I would not use the Mewlon due to the ugly diffraction spikes produced on Jupiter, Mars, Saturn and bright stars.
I had hoped that I'd been clear enough on my intentions and rationale on this on the early posts of this thread, but I also understand that you are trying to be help me out here to make my decision, so here goes again:
- At home (urban, heavy light pollution, no private backyard or garage to store equipment, but peaceful backyard for all the residents of the apartment complex where I can temporarily set up and observe) - lunar, planets (when they again head up north), double stars
- For DSOs I have to pack up and drive to a dark site. Because life intervenes (kid, work), I get myself there far more seldom than I'd like, but most of you know that's just the way life is for a middle-aged working parent.
For DSOs I've got my bases covered for the time being: C9.25 and 4" Tak on AZ-EQ6 - bigger scope to reach deeper, Tak for wider fields (up to 3.6 degrees of bliss; C9.25 won't slay it at that...). Very nice, still portable combo that serves me well. M180 doesn't need to compete for its place in this setup.
Since I currently have too little time for serious observing at a remote site, I like to get most out of my shorter, more compromised sessions at home. Moon and doubles may not stir the imagination like distant galaxies and swirly nebulae, but they quench the thirst when other objects are not available, and if you truly love to do something, you have no choice but to do the best you can within the circumstances you live in.
Now, the 4" Tak is quite a superb performer and in terms of sharpness, withstands pretty much all the magnification arctic skies can deliver. But as I wrote earlier, I'd really like to have a bit larger exit pupils for high magnifications. M180 can deliver those. And as I wrote, I'm quite confident it's just enough small and light and - very importantly - with less demanding mounting requirements, that I, personally, would actually use it as a backyard scope. C9.25 is not - I know, I live with one...
And as for the diffraction spikes, I've had Newtonians, and I can live with them (with spikes that is - not with Newts, too large for my current habitat). I don't love the spikes on planets, but if the image quality is otherwise good, they are not a deal breaker for me.
Edited by Axunator, 18 April 2019 - 03:08 AM.