Maksutov like planetary scope.

[pluton]

Hello,

I am looking for a small planetary and lunar telescope, and I doubt between two scope, one is a C90, that I heard good qualities, optical and mechanical, other is a 4" Nexstar ,also small and not too much weight...

In your opinion there is others more economical alternatives, but also with ood quality ?

I have a opportunity of to buy ,second hand, a 6" SW Maksutov, optical tube, but I think that this option can be a weight solution, but it is I think a good planetary scope also, ....more specialized maybe ? This for me is more complicated as I must to buy a big monture..., more garage, more cooling I suppose, more weight....all this worth ?

 

Thank you in advance for your opinion and advice...,

Regards,

Paulo

[spaceman_spiff]

Hi Paulo,

I have a 6" SW Maksutov that I got second hand (about £300) and it is a great planetary scope. For me it had several advantages over a apo refractor:

- Cheap (for the aperture)

- CA no worse that an apo (any fringing is fixed in Registax)

- Compact (my old EQ5 easily handles it)

- Tough (it is very well built and collimination is not a big issue because optical surfaces are spherical).

Admittedly, I haven't had it under stars very often because I have been con concentrating on DSOs (which at F12, the Mak will not perform well on). My first attempt at Jupiter with the Mak was great - it was low (about 15 degrees or so) so I know the scope can give more.

[mikeDnight]

The SW 127 and 150 maksutov scopes are both excellent for planetary. The 150 is a bit on the heavy side but its a great scope. An eq3 will carry the 127 and an eq5 will carry the 150 well. You could use an AZ4 which would carry either scope well but its only a push/pull altazimuth, though it is solid. An eq mount would be better for high power work as you can track using manual slow motion controls. Motor drives are nice but not essential, and I'd suggest you avoid anything at the cheaper end of the market that involves computer driveeq3

Mike

[baggywrinkle]

I have a SW Mak127 as a grab and go and it gives great viewing for Lunar and Planetary.

The OTA is very light and the optics are excellent.

[michael.h.f.wilkinson]

The SkyMax 127 always punches well above its weight on planetary, the 150 is optically excellent, but heavy. My C8 OTA weighs about the same. Whilst the secondary obstruction of the SCT might be larger, 2 inches of extra aperture show, especially when imaging. I had a very good 6" F/8 "planet killer" Newtonian with small central obstruction, but the C8 gave me more detail (albeit at a slightly lower contrast) than the 6" Newtonian could. The SkyMax 127 would be much more grab-and-go than the SkyMax 150.

[Peter Drew]

For Lunar and planetary observation I would recommend not less than a 127mm aperture for satisfying results with a Mak.

[Dave In Vermont]

As our colleague, spaceman_spiff, has brought up CA in APO refractors & Maksutovs, it should be understood this is why 'apo's' became popular - to reduce CA (chromatic abberation) to the lowest degree. Different wavelengths of light, red & blue, have different focal-lengths. And this is why CA is present in two-piece lens-elements. The 'achromatic' refractor does have a bit of this. Toward reducing CA is why two different lens-elemants are made for the achromatic-refractor, one of crown-glass and the other of flint-glass. These glass types differ by their density to offset the disparity in the focal-length inherent in just a single lens-element.

Maksutov-Cassegrains, as a combination of mirror's and a glass corrector-plate, do not suffer from CA in any excessive way - a bit more than the similar Schmidt-Cassegrain - due to the heavier front corrector-plate - but not nearly as much as a refractor, which is all glass lens-elements.

Most people who use Maksutov's understand this and realize that the cost difference between, say, a 150mm apochromatic-refractor and a 150mm Maksutov is huge! If no CA is tolerable for one's purpose, I'd suggest a reflector-telescope instead. But these also have some special optical-abberations to consider. But I'll leave that to another thread.

No one type of telescope will do everything superbly. A bit of a trade-off is part & parcel in all optical-systems. Regards abberations in the Maksutov design, this is a good read:

https://starizona.com/acb/basics/equip_optics101_maksutovs.aspx

As the owner of a SW 150mm Maksutov, I've found this to be an excellent telescope. It has a narrow field-of-view, yes.  And using this on smaller targets is great! These can give superb views of other planets and comets and smaller DSO's - like ring-nebulae and globular-clusters. These seemingly little telescopes are true power-houses on these things. But trying to use one for extended objects like the Veil Nebula will be a disappointment.

Hope this helps -

Dave