SIDO

I agree with Andrew here but all of the right conditions have been met to evolve a species intellectual enough to bring such a question as you ask, that in itself might que the question beyond just the slight unique character of the system and would be my reason to ask the question but of course I am not. To construct such a solar system would require a 4.5 billion year ongoing project still underway as we speak so as this would not be a set it and forget it task, so at random it is entirely possible but planned it would be quite impossible. Freddie...

One reason being is that a 4" frac will not be as bothered by atmospheric dispersion as atmospheric dispersion correctors for visual are only suggested for telescopes 200mm and up, it's for this reason I think even 90mm f10 achro's will show some benefits but also have false colour of their own meaning Ed and Apo scopes will do better than achromats in this area. For achromats f11 is where false colour tends to show less distinction but not all f11 achromats are equal and a better optical figure will often show less false colour, too bad the f11 and up achromats are harder to come by these days mine is 30 years old now and I still can't part with it...Was the one scope I had that saved the 2018 Mars opposition when the others failed me. Freddie.

Best of luck of course and do work on collimation by laser or cheshire, you should be getting some pretty pleasing views of Jupiter with a 250mm dob and there must be a significant issue preventing that. Freddie.

I answered your question in response to the way you framed it, the generalization of your question allowed this to happen. And yes vehicle load times are another area where small fracs trump larger dobsonians, thanks for throwing that one in there. The op already has the 250mm f4.7 dobsonian, of course a 250mm dobsonian will outclass a 90mm f10 achromat visually for planets and that has been fully represented in responses thus far and I was not disputing this. But the refractor is the fastest scope on the planet outside of f ratio and on nights were time is limited due to responsibilities or impending cloud the achro can get the job done and be stored away before the dob is acclimated and ready for collimation... I was going to leave it right there and even said so... Freddie.

Yes indeed it will... While one guy waits for his 250mm dob to equalize with the surrounding air temperature the other is observing with his refractor, this is true providing everything is equal mount wise and both individuals are utilizing none goto altitude azimuth mounts as goto and equatorial mounts require additional setup times. A refractor will also not likely require collomation as a newtonian mounted dobsonian most certainly will and newtonians above 150mm most definitely will. There are a few more areas of trumping but the formentioned are hands down trumpers so I'll leave it right there 😉 Freddie.

Better late than never they say, Welcome to SGL...Best of Luck and Clear Skies of course. Freddie.

I bought some heavy quite expensive wheels for a diamond plate mobile work table in my shop some years back, the wheels on that cart in the shot are awesome...

Its a very moving image, or to say it is a surprisingly good image.

That's a cracking image, nice setup for capturing too...

Same here, Version 2 is sharper and has better colour. I as others have said think V2 is a significant improvement over V1...

Very nice all around, scopes looking great and changes ring of freedoms to be enjoyed... Best of Luck with it all and Clear Skies of course. Freddie.

Welcome to SGL Yash, Best of luck with your paper... Freddie.

Awesome, Thanks for sharing...One of my favorite lunar scenes...

11 observing days since Jan 1 here in Wisconsin, only one of those a Milky Way sky and the rest all high thin cloud where extended objects were only visible by astronomy camera and longer exposures and even then the stacked images were lacking. Has to be the worst in many years here and last fall was also a bit of a washout but the first part of last year was quite good, clears sky's soon I hope... Freddie.

Welcome to SGL, Best of Luck with your new telescope and Clear Skies of course... Freddie.

Beautiful shot!

So indeed the Gso my supplier is listing for $30 can be had for much less and my eyes for aberrations are still quite good.

Ok this is making sence now, in the US the top reducer pictured is branded Gso through my supplier and the more expensive one so I'm guessing that the supplier is running out old stock or Gso is just supplying them with theirs. Here the wider aperture reducer is unavailable at least through the suppliers I am dealing with branded Gso.

Clearly two different objectives loaded in two different cases and swaping them in use its my opin that the Svbony is superior, but just my opinion and I haven't tested more than these 2 units against each other.

I bought 2 different focal reducers one from Gso and one from Svbony, they are different by clear aperture and case length with the Svbony having more clear aperture but both 1.25. The Svbony is clearly superior, since beggining eeva I decided to upgrade focal reduction from two 24mm binocular objectives I installed in filter cases some 8 years back for visual purposes and am very pleased with the Svbony and plan to replace the Gso I'm now employing ahead of one of the two cameras I run together on my eeva rig. I also own an Svbony dovetail and a helical focusing eyepiece adapter and am also pleased with those items. I own Baader, Celestron, Meade, WO and a host of brands and if the shoe fits wear it I say. I always work with sellers using a full return policy and have been happy with some brands components and unhappy with others per my specific needs. With all that being said Svbony is selling the same focal reducer Gso is selling for $30 for only $11 but Svbony is also selling the reducer I wound up preferring for $20, of the 3 Svbony items I purchased the total savings was better than 50% of cost elsewhere for very comparable items and of course that put more kit on the stick... I should add that my eeva scopes are running at f 1.8 and f 2 and the Gso reducer may work just fine in slower applications as many users like the Gso reducer just fine. Freddie.

Excellent...

I understand both the cost issue and the weight difficulties, having a spinal cord injury and a 10 pound weight limit with my left arm and a one # limit for my right while being gimp without being able to look up or to the right most telescopes are more a burden than a benefit, have been observing forever and have owned and operated alot of heavy scopes and still own a few but one has to succeed where one can. A small short focus refractor on an ultralite alt az mount or a small table top 4.5 to 5 inch Dobsonian and I had to choose only one it would be the table top dob because it would be a better all rounder compared to a short focus achromat on bright target's like the moon and planets chromatic aberrations would not be an issue like with the achro. Down the road something like the revolution imager would expand the lightweight horizons of such a scope lightweight is the kit and a small roller table and chair = no lifting. I currently am using astronomy cameras and small scopes with a lightweight utility desk and laptop computer all on wheels I just roll the stuff out of my garage and within a couple minutes I'm up and observing. Hope this helps, Best of Luck and Clear Skies of course. Freddie.

Welcome to SGL Joe, Best of Luck and Clear Skies of course... Freddie.

Observing or Imaging without a tracking mount...