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telescopes for visual planetary observation

Ags

By Ags
in Discussions - Cameras

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Ags

Ags

Posted
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Next year I might have enough money to buy a larger telescope than my current 102mm Mak. That's if I can quit buying eyepieces! ;-)

The one I keep coming back to is a C8 SCT. But that's a lot of money (nearly £1000 on a CG5). I was wondering what options I have, given the main target would be planets.

I'd rather avoid the weight and complications of an EQ mount... Putting a portable scope like a C8 on an EQ mount seems a waste of portability to me. (But I'd pay an extra 200 for an 8SE).

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John

John

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I had some of my best views of Saturn with a fork mounted C8 SCT a few years ago even though I don't think SCT's are the optimum planetary scope. Perhaps an Skywatcher 180 maksutov-cassegrain on the Nexstar SE mount would be a good setup :)

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Ags

Ags

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No budget really - I just have to save up for longer for a more expensive telescope. I've seen people are a bit negative about C8s on planets - why is that? I'm attracted to the size and weight of a C8.

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astroeddie

astroeddie

Posted
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after a few weeks of pondering, thats the scope I've decided upon. The Skymax 180 Pro. With a F/15 the planets size must be pretty big. Even more so with barlows ofcourse.

There's one on astro buy and sell for £750 with HEQ5 mount.

Another is the Orion Optics OMC 140. £700 OTA £889 deluxe version.

Eddie

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Ags

Ags

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John, I suspect a Skymax 180 would be too much for a NexStar mount.

I've been thinking about the smaller skymax 150 as well...

Surely a C8 would be pretty good too? As far as I can see, it should perform similarly to Mak...

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Moonshane

Moonshane

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don't know the scope but having bought several things off Paulo, can vouch for him - really nice guy and totally trustworthy.

from my experience, a long focus dob would be excellent. if you could get an 8" f8 dob, this would be superb on planets. my own 6" f11 is far better than my 12" on Jupiter for example. I have just got an 8.5" f8 mirror to build a dob to see what this is like cf my 6"

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John

John

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I own an Intes MN61 - the maksutov-newtonian version of the MK67. It's tiny central obstruction (19% by diameter) means it delivers very sharp and contrasty planetary images - reviews I've read have compared it favourably to top quality 5" apochromats. I've not done that comparison myself but the views of Jupiter I've had with the scope have certainly been as good as the 6" chromacor-enhanced refractor I used until recently. A previous owner of my scope claims to have seen detail within the Great Red Spot with it on a night of excellent seeing.

The mak-newtonian design is not as compact as the mak-cassegrain of course but at F/5.9 the MN61 is capable of excellent wide field views as well. That rare thing - a true all-rounder !.

Apparently Intes Micro make a 16" mak-newtonian - it must need a colossal mount but the planetary views would be sensational !.

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John

John

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Hi John, are you saying this could be the ultimate planet scope:

Maksutov Newtonian - Skywatcher Explorer 190MN DS-PRO Mak-Newt Astrograph

At ten kilgrams and a long tube, I guess it would need quite a mount.

I've not tried the Skywatcher mak-newt although I believe it's design is optomized for imaging with slightly larger secondary than the Intes and Intes Micro equivilents. It probably performs very well visually though - perhaps I'll get to try one at the SGL6 star party next year :)

My 6" mak-newt weighs 10 kg as it happens so the Skywatcher is not that heavy as mak-newts go. The tube walls on my scope are 3mm thick which accounts for a lot of the weight - the Russian ones are incredibly solid though and hold collimation in the same way a refractor does.

I'd be very cautious about using the "ultimate" word though :)

I'd get plenty of justified flack from the owners of long focus newtonians for one thing !.

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brianb

brianb

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The tube walls on my scope are 3mm thick which accounts for a lot of the weight

And also have a lot of heat capacity ... the trouble with Maks above about 5" aperture is that they never seem to cool anywhere near to ambient, unless assisted by some sort of active air circulation system. SCTs cool slowly but Maks of the same aperture are a lot slower to cool ... impeccable optics are of little use if the definition is ruined by tube currents.

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ollypenrice

ollypenrice

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I would not look at an 8 inch SCT for planetary observation because mine was distinctly inferior to the 10 inch which replaced it. I don't advocate a 10 inch but just mention this to show that the 8 inch was not 'all the way there.'

So, yes, a larger Mak, an Mn190 or one of the very reasonable budget apos like the ED120 or Meade 127. My own favourite planetary scope is our TEC140, which I prefer to the 10 inch SCT. The Meade 127 was not far behind it in visual use. Refractors cool fast, are less susceptible to seeing (maybe?) and are unambiguopus regarding focus. I like them but will now shut up!!

I would also think about a C9.25, the only sub 10 inch SCT on my imaginary list.

Olly

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ollypenrice

ollypenrice

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Still no love for the Tal 150k? Are they not worth the asking price? They read well and seem a good choice for smaller mounts..

Only for want of experience, I daresay.

Oh, what about the Altair Astro modified Mak tested by Ian Morrison recently? I think he has the credentials and liked it!

Olly

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russ

russ

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Quality of SCT's seems to vary quite a bit. Of the 9 i've owned, 2 were excellent, 3 good, 2 not so good and 2 were dire. The bests one were not the Celestron's surprisingly but the Meade's. My LX6 10" F10 and LX50 8" F10 ota's were superb, as good a SCT as you could hope for. The two dire ones were a Meade LX200 10" F6.3 and a Celestron C5 F10.

Based on that LX50 8", i would highly recommend an 8" SCT but there's a good chance you'll get a duffer. Rob's Celestron C8i was a good example of a poor performing 8" SCT. Just couldn't yield a sharp image.

No experience of the Tal K series scopes. I know they have issues of their own from reviews i've read but all scopes have flaws. Best to find some good reviews and judge from that I suppose.

My own personal recommendation would be a good planetary optimised newtonian or a Mak. Shane's Orion Optics 150 f11 Deluxe was simply gobsmacking for planetary detail.

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John

John

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And also have a lot of heat capacity ... the trouble with Maks above about 5" aperture is that they never seem to cool anywhere near to ambient, unless assisted by some sort of active air circulation system. SCTs cool slowly but Maks of the same aperture are a lot slower to cool ... impeccable optics are of little use if the definition is ruined by tube currents.

Agreed Brian - my 6" takes a good hour to cool fully (which I expected of course). For that reason I'd hesitate before owning a larger aperture one, unless I can have an observatory to keep it in !.

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beamish

beamish

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And also have a lot of heat capacity ... the trouble with Maks above about 5" aperture is that they never seem to cool anywhere near to ambient, unless assisted by some sort of active air circulation system. SCTs cool slowly but Maks of the same aperture are a lot slower to cool ... impeccable optics are of little use if the definition is ruined by tube currents.

Having not owned a SCT I can't make the comparison, I can however say that with a little fwd planning , cooling the 7" Mak has never been a problem.

If the skies look good I nip downstairs and plug in the fan and get that running. Within an hour the scopes good to go- quicker if i take it out and mount it too ! I've certainly never had to wait before using it.

Not wishing to cause offense to anyone, including yourself Brian, but personally I hear this "complaint/criticism" about larger Maks so often and just can't understand it !!! ...........a bit like " how difficult it is to collimate" !

Rubbish.

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