Sure, a 4 inch refractor can approach an 8 inch when the seeing is crappy when viewing the planets. And it's not just people with reflectors complaining about Mars.. In my experience, if a planet is crappy in my 10 inch, it's crappy in my 4 inch. When it's amazing in a 10 inch, (or 8 inch) it won't be as amazing in a 4 inch.
I should note that I suspect that many of those having difficulty with Mars were not skilled observers and were trying to observe Mars in the early evening when it was low on the horizon. This is rarely productive. The fact that newbies are having difficulty viewing the planets is not about the right telescope, it's about understanding planetary observing. Sure, you get good views with your 4 inch because you know what you're doing but that's not what those threads were about.
In any event, my point is a little bigger than that. The planets are transitory, they come and go. Pretty soon, there will be no planets to observe. That's a game changer.
I spend a lot of time viewing doubles from my urban backyard. Refractors are nice for the easy ones, the double double is doable in a 60mm. But challenging doubles are like challenging DSOs, is M13 OK as a blob or would I rather resolve it? Is Lambda Cygni OK as a slightly elongated disk or would I rather resolve it clean and wide?
The focus of these discussions is generally about the one thing a 4 inch might do that's competitive with an 8 inch and in the process, the things an 8 inch does far better get lost in shuffle.
That's my point, something to think about.
If I had to decide between an 4 inch refractor and an an 8 inch Dob, which one would I choose??
That would be a difficult choice, I would really want to have both. The refractor is handy, an easy scope to deal with. But I would probably go with the 8 inch Dob simply because it has the capability of providing better views of most objects. It may not deliver all the time but as an all around performer, it'll show me more.
When Clyde Crewey, a long time CN member was just getting started, he called up Televue. He got Al Nagler on the line. Clyde asked Al about the TV-85. Al told Clyde that for anything that fit in the field of view, a decent 6 inch Dob would show more.
On your first point about 4" apo vs larger reflector in crappy seeing, my experience is just a little different, although unlike you I live in an area under the jet stream when declining temperatures during the night are the norm. Yes, a larger reflector can show more if seeing and cooling cooperate, so we agree on that but where we differ is in crappy seeing, which I have to contend with regularly. In my experience if seeing is crappy in a 4" apo it is a whole lot crappier in a larger reflector.
Some people in this thread have said that if seeing is crappy they will just come back another night but under the jet stream, the seeing is kind of crappy almost every night, and in the pacific northwest there are also a lot of clouds to contend with, so coming back another night is not really a good option. For people who have to deal with crappy seeing on top of cooling issues on a regular basis a 4" refractor is a better choice for planetary since it will give consistently less crappy views than a larger reflector of SCT under those conditions.
On your point that newbie planetary observers may have been looking at the planets when they are too low, I would respond by pointing out that there may also have been collimation issues and that a small refractor doesn't need collimation. Since a refractor is easier to use in a variety of conditions and refractors "just work," I think a 4" apo refractor is a better beginner telescope than an 8" reflector or SCT.
I've compared my 4" apo to my 8" SCT side by side on Mars when Mars was above 45 degrees and the SCT had been cooling for over four hours. The seeing was somewhat crappy but the 4" gave acceptable views and some good details could be seen during brief periods of stability. The 8" gave views that were somewhat less acceptable than the 4" so after an hour of going back and forth between the two, I put the 8" in the garage and spent another couple hours with the 4".
Further, it is going to be years before Jupiter or Saturn higher in the sky for northern observers. So looking at planets when they are low on the horizon isn't just a newbie issue. Sure, I can wait until midnight for Mars to rise above 45 degrees (well, actually last night I couldn't because I started falling asleep at 10:00 and had to pack it in, but was still able to see the southern polar cap and Mare Sirenum and Cimmerium in my 4" when it was lower than optimal for viewing). But I would have to wait years before Saturn or Jupiter climb that high.
Turning to your main point that pretty soon, there will be no more planets to observe, we probably have another couple months to observe Mars -- that's pretty much the only planet I am looking at these days, since Mars won't be this close again for another 15 years.
But in a way I am looking forward to the planets being gone since I will then be able to turn my attention to double stars again. I only started becoming interested in double stars last year but have found that I prefer the aesthetics of double stars in the refractor, both because of no diffraction spikes and also because of the aesthetics of viewing stars in smaller apertures as discussed in this thread.
Also, the same issues of seeing and cooling also affect larger reflectors more than smaller refractors when viewing double stars, just like viewing planets.
Sure there are double stars that cannot be fully resolved in a 4" that can be in an 8", but there are thousands of double stars that are within the range of being fully resolved in a 4". For instance, last April, I tracked down STF 1830-1831 in my 4" and was able to resolve all 7 components -- it is a fantastic multiple star system. I haven't tracked this particular double star down in any of my reflectors, but based on my experience viewing other double stars in my other scopes, I cannot imagine a double star like this would look any "better" in a larger reflector. It is all about picking a target to match your scope, and there are hundreds if not thousands of double stars that are well matched to a 4" scope.
Edited by Ihtegla Sar, 22 October 2020 - 12:38 PM.