[Hotdog (Anthony)]

Originally Posted by mental4astro

The main thing with Maks is they have very long focal ratios, typically f/13. Sure, they give high magnifications very easily, however, they are limited to how low in magnification they can go. This restricts their ability to give bright images of DSO's (most DSO are seen at their brightest/easiest at low power). As consquence, unless you know what you are looking for, you just won't see many of them, especially from urban areas.

They also have a restricted capability to how wide a field of view they can give due to the size of the hole in the primary mirror. SCT's are also limited this way. It is more of a concern with low powers. And you can't use 2" eyepieces with either.

It's true that the Maks have long focal lengths (both of the ones I mentioned are f/12 focal ratio so have a focal length of 1800mm) and I understand that they won't be able to achieve very wide fields of view. Note though that the current generation of 6" and 8" Skywatcher Maks and the Bosma Mak I mentioned have 2" focusers (and presumably primary mirror holes sized accordingly) so they won't be quite a limited in this respect as the 1.25" Maks. I don't have the specs for exactly what the maximum true field of view really is, but if the maximum illuminated image circle is somewhere between 1.25 and 2" (which seems a fair assumption) then it'll be between 1 and 1.6 degrees.

Given the light pollution I will usually be contending with I figure that no telescope is going to give me particularly good views of DSOs, hence my focus on lunar/planetary viewing in my initial post. Lower magnifications do increase the apparent surface brightness of extended objects but they also increase the apparent surface brightness of the sky by the same factor, the contrast stays the same so while low magnifications can help to some extent the only way to really win is to find darker skies...

For when low magnification, wide field views are what's really needed then I do have the 20x80 astro-binos. I figure they're a good complement to the telescope so I'm covered for either extreme without requiring very low magnification from the telescope itself.

However, SCT's have an advantage over Maks. SCT's for one are a little faster optically, f/10, but you can also use focal reducers on SCT's that further reduce the focal ratio of f/6.3, making faint DSO's a distinct possability. Many folks use these focal reducers in imaging, but this one is very useful visually too. These focal reducers don't work with Maks.

That's a good point, the availability of focal reducers makes SCTs a little more versatile. Odd in a way that there don't seem to be any available specifically for Maks, fundamentally they're not such different telescopes (both long focal length Cassegrain configuration catadioptrics) so I would think it would be possible.

I've got a Celestron C5, a 5" SCT. As you're in Sydney, I'd be happy to show it to you some evening. You can compare it to a dob too.

Thanks, that's a very kind offer, I may well take you up on that at some point.