I picked up an Intes MK91, recently, in like-new condition. I’ll be putting it up against my TEC160ED. At 228mm and f/13.5, I’m curious how it will perform compared to a top-notch 6” refractor.
Pics of the Santel !
Personally I'd expect the MK91 will win that contest easily if (a) the comparisons are done at equal magnification (b) the MK91 is insulated and perfectly collimated, and © the seeing is half decent... but I'll suggest you'll have to wait till its planet season to really see it stretch its legs.
The reason I say that is that is while I had an MK91 some years ago, it was pretty routine to take it to 300X most nights and 500X was not uncommon. It also handled average seeing deceptively well; often others would be grumbling about the seeing while I'm thinking "huh ? looks OK by me ...".
In particular there was a night of exceptional seeing with Saturn high in the sky (80 degrees) and at 600X it was possible to see the Encke division in the rings - the rings looked like they had grooves, like a vinyl record. With several present it took us a while to understand and really take in what we could see, as a CPC1100 and 12" LX200 alongside couldn't match it for details. Encke is comfortably beyond any 6" scope/eyepiece/observer combination.
Another interesting test is how many of Saturns moons can be seen, though the MK91 should win that easily thanks to the aperture.
It was that MK91 that convinced me to acquire my current big mak, which likewise does not disappoint.
Edited by luxo II, 15 April 2021 - 10:37 PM.