comparing optics

[Steffen]

I've had the joy of looking through quite a few big Dobs lately, including some premium SDM ones. They blew me away on the faint stuff, but on Mars or Saturn my puny little Mak held its own quite impressively. And while the big Dobs impress I wouldn't want to own one (and not being able to afford it is only part of the reason).

The funny thing is, owners or proponents of big Dobs won't even bother to look through a 6" Mak at star parties etc. I think they're the ones missing out.

Cheers
Steffen.

[Satchmo]

Originally Posted by Steffen

The funny thing is, owners or proponents of big Dobs won't even bother to look through a 6" Mak at star parties etc. I think they're the ones missing out.

Cheers
Steffen.

Hi Steffen

Large dobs have to be carefully collimated and cooled and the seeing has to be good to work at their best for planetary observing - just you look through a scope that has a certain name tag on it does not mean it is working optimally !

On the Thursday night at SPSP we spent time later in the night on Saturn with Mark Axisa's newish 18" F4 SDM. After I gave the collimation a tweak The seeing was such that frequently the view went rock steady and the Cassini Division looked almost laser etched .

Including the crepe ring we saw the ring broken up into 9 odd rings and the pentagonal polar darkening was obvious. I've been looking at Saturn through various scopes for 40 years and this was by far and away the best view I've ever had - the combination of image scale ( X350 ) - a nice bright image and the incredible resolving power combined to give what everyone in the group agreed was the best ever view of Saturn .

While I'm sure your Maksutov would give diffraction limited sharp view on most nights due to the average size of seeing cells generally being 6" to 8" - I would not trade that restriction for the potential offered by a large quality scope. The views in this scope on the Thursday night were simply mind blowing .

[Steffen]

Originally Posted by Satchmo

Large dobs have to be carefully collimated and cooled and the seeing has to be good to work at their best for planetary observing - just you look through a scope that has a certain name tag on it does not mean it is working optimally !

Very true, I'm amazed that some owners of high-end telescopes can't be bothered with accurate collimation.

While I'm sure your Maksutov would give diffraction limited sharp view on most nights due to the average size of seeing cells generally being 6" to 8"

Actually, nights that allow me to observe at the Dawes limit (about 0.77 arc seconds) are rare. I wish I had spent more time on Saturn that Thursday night, I was mostly chasing doubles, which at 360x was quite rewarding nonetheless.

Cheers
Steffen.