telescopes for visual planetary observation

[sixela]

It's not like that will have a resolution if every member simply lists a telescope and wanders off.

As I said in a previous (decidedly on-topic) post, I outlined a set of basic requirements, and if the scope meets them it's a fine planetary scope.

That's why we now have two pages full of almost any scope under the sun that has at least 150mm of aperture, and if the thread simply continues like that instead of focusing on the underlying principles we'll have four pages more without any form of resolution. If you're rational, these days you're likely to pick exactly *which* planetary scope you want depending on other things than "planetaryness".

*All* these scopes have the potential to be fine planetary scopes, and the "my scope is more planetary than your scope" is a sterile debate (which fortunately hasn't erupted yet here) -- it made sense when the majority of scopes were achromatic refractors, but those days have gone since long.

In the "my scope is more planetary than yours" debate, by the way, nothing beats the Secret Weapon: a GEM-mounted 250mm Schiefspiegler. Haven't seen one of them yet in the thread, so I thought I might just lob it in the arena .

[Ags]

The CPC on special does sound like a nice idea. It seems you need to make sure the SCT optics are OK and get a refund/replacement, if the other posters' experiences are anything to go by.

To be honest I am thinking (despite all the fantastic scopes mentioned in this thread) of a quick upgrade next year to a skywatcher 6" F8 - although that is a bit of a no-future option. The mount wont be good for anything else, and I'd still want to get a bigger scope... And I'm not certain it will be that much of an improvement over my Mak.

[John]

It's not like that will have a resolution if every member simply lists a telescope and wanders off.

As I said in a previous (decidedly on-topic) post, I outlined a set of basic requirements, and if the scope meets them it's a fine planetary scope....

No problem with that - it was the tedious debate over the testing methods of a particular person that I thought was distracting - thought I was over on "Cloudynights" for a moment there

[dweller25]

£395 gives you planetary views like this .......

http://stargazerslounge.com/imaging-sketches-unconventional/119768-jupiter-14th-november-2010-a.html

[Mr Spock]

Um, but you are using 10"... That's a very similar view to what I've been getting tonight (before the clouds arrived) with my OMC-140, but I have more detail in the south polar region.

[dweller25]

And here is what Roland Christen says ......

What is the Best Planetary Telescope - How To

[sixela]

To be honest I am thinking (despite all the fantastic scopes mentioned in this thread) of a quick upgrade next year to a skywatcher 6" F8 - although that is a bit of a no-future option.

Personally, I think that an upgrade to 10" or (if you want to invest for those three-four days in a year the seeing is really stupendous) a 12" would make more sense. That gives you an aperture that is close to optimal on anything but the very best nights (though I should warn you that I have seen nights in which my 16"er was beating a 300mm Orion Optics scope handsomely, and if you even plan to move to Florida, you'll want a 22").

To avoid having a humongous mount, you could consider an autotracking 10" Skywatcher Dob (not that these are less bulky --the base is cumbersome-- but they don't weigh a ton and are very stable).

Personally, I like a plain Dob on a platform even more --the movements are still as smooth as on the "lone" Dob-- but I don't know if the current cheap source for platforms in the US, Atomic Platforms, ships to Europe. But there are ways around that ( weship-it.com is popular in Belgium because the customs process for USPS packages is atrocious here).

[dweller25]

Um, but you are using 10"... That's a very similar view to what I've been getting tonight (before the clouds arrived) with my OMC-140, but I have more detail in the south polar region.

I see you also have the Skywatcher 10" reflector.

Which scope do you see better planetary detail with - the OMC140 or the 10" ??

[KaStern_Former_Member]

Hello AGS,

what You need is enough resolution and enough contrast.

You get both from aperture.

But there can be some negative impacts on both contrast and resolution:

- bad seeing

- bad collimation

- bad optics

- thermal issues

- too much colour aberration

- too big central obstruction

- combination of the above

So if seeing is good:

- make shure that collimation is perfect

- put the scope out earlier to let it cool down sufficiently

- make shure that your telescope optic is good enough

- and: be shure to use an adequate magnification and brightness.

I think the minimum requiremnts are 6" good aperture, or more aperture

if there are negative aspects such as a bigger than 20% central obstruction,

visible colour aberration, a little bit of spherical aberration, slight astigmatism...

If I had to spend 1000 pound I would buy a very good 8" f/6 or f/8 mirror,

add a good 40mm or smaller secondary, a good low focusser, a solid tube

(not too small, 250mm inner diameter or so, sufficiently long to serve as

a dew shield for the secondary), flock the tube inside and add a fan to

get rid of tube currents.

Cheers, Karsten

[Revs]

This might be worth a look..

U.K. Astronomy Buy & Sell

[Nexus 6]

Another vote for the Celestron cpc range. As has been mentioned easy/quick set-up, solid as a rock, great optics.

Alan

[sixela]

Another vote

Ah? I didn't know it was a telescope beauty pageant contest. That explains a lot .

I like the CPC range - I almost ended up with a C9.25 myself. Enough aperture and they're on a tracking mount (which is, for planets, very important).

Whether on that kind of budget you have other choices depends on many factors not discussed in this thread, though. (Don't forget that you *will* need a dew prevention system for anything with lenses in front! And if you have a closed tube catadioptric scope, you'd better also have a Lymax cooler).

One scope I didn't see mentioned: Tal 200K/250K. Short and compact like other folded catadioptrics, but less issues with cooling and dew.

[michael.h.f.wilkinson]

I think what this thread shows more than anything is that we are spoiled for choice.

CPC are nice, though I really like my German mount (sets up in 5-10 minutes, cooling time is the main issue). The nice thing about Maks/SCTs/RCs is their compact size, which facilitates ease of set-up and transportation. Many have said: the best scope is the scope you use most. If you have a more-or-less permanent set-up, the extra bulk of the (much cheaper, inch for inch) Newtonians is not a problem. Sixela gave a very sensible list of criteria, each of which needs to be balanced against your own personal situation. My only addition to the list is the requirement of good, high contrast EPs well corrected for the light cone of the scope.

If your budget allows, the best scope for planets I have ever seen listed is the APM 530mm F=6500mm APO found here:

APM Apo 530/6500 CNC

You would need your own mountaintop, but as the list price of the OTA is 825.000,00 € and another 500.000,00 € (ish) for the mount, acquiring your own mountaintop observatory is not a problem.

[Mr Spock]

"I see you also have the Skywatcher 10" reflector.

Which scope do you see better planetary detail with - the OMC140 or the 10" ?? "

They are very different. The 250P reaches finer detail but at a lower contrast. For example on Jupiter, the NEB, shows fine white ovals against a pale fawn band with the 250. The OMC-140 shows dark 'knots' against a dark brown band. The OMC-140 also picked out fine bands in the south polar region at low powers (x100) whereas the 250 just gave a pale 'block'. However, the OMC-140 lost it at x222, the 250 was stable at x240.

Most of the difference in magnification is due to how they react to seeing conditions. The contrast difference is down to superior optics and it why I'm thinking about a 1/10th wave Newt.

The OMC-140 can produce the kind of inky black lunar shadows, black cassini division and fine colours that is beyond the 250, but the 250 can reach (with the right seeing conditions) fine detail that eludes smaller scopes no matter how good the optics.

[Mr Spock]

As an ultimate planetary scope I'd love an OMC-200 deluxe. But unless I cop the lottery the £2.6k is beyond me...

[Ags]

Well, this thread has made up my mind. When I have the money, I'll get a 200mm or 250mm dob with tracking and/or goto.

[Moonshane]

you know you wanna

I'd definitely get the biggest you can handle - the difference in aperture really makes a massive jump in detail even from not so dark sites.

[A McEwan]

As an ultimate planetary scope I'd love an OMC-200 deluxe. But unless I cop the lottery the £2.6k is beyond me...

There was one of those on ABS for £1300 recently, or similar price I think...?

[GazOC]

There was one of those on ABS for £1300 recently, or similar price I think...?

Yep that one was quite "cheap", they come up around £1600 reasonably regularly.

[dweller25]

The OMC-200 would be my ideal scope - apart from the cool down.

[GazOC]

I've settled for the "poor mans version", the Skywatcher 180mm f15.

[ollypenrice]

Yes, I don't like the sound of all this telescope down time while your instrument goes from expert to expert so as to furnish the forums with the stuff of fervent controversy! What happened to looking at the planets? In reality all sorts of instruments will give good views. We should maybe remember to look through our telescopes, not at them...

Olly

[Mr Spock]

I've plumped for a C9.25.

Is it better than my 250mm? No, but it's half the length, half the weight and twice the fl.

[GazOC]

I've plumped for a C9.25.

Is it better than my 250mm? No, but it's half the length, half the weight and twice the fl.

And twice the cost.....

[Mr Spock]

Every form of indulgance has a price