PLANETARY VIEWING ?? -aperature rules?or telescope type?

[ngcles]

Pt 2 ...

Originally Posted by robz

The newtonians have and are a proper nuisance, in having to check and collimate the optical path, rotate that bloody tube to get to the eyepeice and are heavy and long, making set up just that bit harder.

I can't (and won't) tell you what to feel and if these are your feelings, a Newtonian is probably not for you and there is nothing wrong with that at all.

Originally Posted by robz

Have never owned a SCT, but have allways wanted a big one............wish me luck coz I'm gonna need it

Don’t for a moment think I’m ridiculing your choice – I’m not. All I hope is that you choose for the right reasons. There are many reasons that make the Schmidt-Cassegrainian a legitimate choice for many people. No argument there at all. Going down that path because you hope for better visual planetary images is not one of them. Going down that path because you believe you are guaranteed higher quality optics … ditto. Some people also go down the S/C path because of peer-pressure or because they find them aesthetically pleasing (ie pretty). Personally I don’t buy telescopes to look at, but if that’s important to you as a buyer, well that’s your choice and I won’t argue about your feelings. Personally I choose a telescope based on what it’s like to look though, not look at!

Very best of luck with your choice and I sincerely hope that whatever you settle on, it will bring you many hours of observing pleasure.


Best,

Les D

[Rigel003 (Graeme)]

Interesting discussion. I understand all the theoretical reasons why a larger aperture gives better results but my personal experience hasn't really shown this in side by side tests. I have an 11" celestron and a 4" Tak refractor and even with careful attention to collimation and cooling in the SCT, it rarely provides more detail visually on Jupiter than the smaller refractor. Brighter, and larger image scale but much softer images 95% of the time. I'd also be wary of the EdgeHD Celestrons if visual planetary studies are your main interest. The vents are passive and not large so don't sound especially effective in assisting airflow, and the flattening optics in the baffle tube will stop you putting in a device like a Lymax cooler that greatly assists cooling.

[mch62 (Mark)]

It only takes about 15sec to remove the secondary to assist air flow as they are Hyperstar enabled. This is actualy mentioned some where in a Celestron manual or on the web site. It won't be long before some one fits a fan to either the vents or at the secondary for more rapid cool down.Personaly give me a good quality Newtonian any day.-( I have an EDGE and there actually quiet good as far as SCT go for Planets but I find a well built newt hard to beat.
Mark

[issdaol (Phil)]

Hi Robz,

Les has done 2 great posts on the aspects thet need to be considered.

On the practical side it really comes down to how much budget and how many compromises you want to make.

I had a really nice US made 8" Meade SCT and a great CPC1100. I also had a very nice 4" refractor (though not as good as the Tak or AP refractors).

MY refractor gave me really nice sharp contrasty views and was simple and easy to setup and did not take much effort to maintain. Due to the lower aperture I found that it's performance on DSO's was lacking but it was a nice scope.

My 8" Meade was very easy to move around and setup. It also performed well across the board but images were "soft" and not as contrasty as the refractor.

My CPC1100 was an improvement on the Meade but again planetary views, while signficantly improved, were a little soft for my taste. Also the CPC1100 was heavier and took ages to cool down to ambient (over 2 hours). Once you get to this size SCT and above you really need to consider cool down times and mechanisms to help reduce this like filtered active fans/vents. As I did not have these, I used to setup my CPC1100 hours ahead of my visual sessions.

Both my Meade and CPC1100 held their collimation quite well so I did not personally find this a problem. Focus is an issue in both of these so I would consider a focuser upgrade mandatory.

When I first used a Mewlon 250 this scope blew away any of my prior scopes in terms of sharpness and contrast. The Mewlon 250 is also easy to setup and use at a reasonable price for the quality you get.

I now have a Mewlon 300 which completely blows away anything else I have used or owned. However, It can be a pain in the behind to setup and breakdown as the total setup weighs nearly 100kg but it is a sacrifice I am happy to make.

For Visual image quality/sharpness/contrast standard SCT's come nowhere near the Mewlons or similar Quality APO's and Similar Quality reflectors.

I have found focus on the Mewlon 300 to be very easy as it has a motorised secondary and the primary is permanently fixed. Also you really have to bounce these around to mess up your collimation.

Another critical thing I have learnt is quality of both the mount and tripod especially for portable systems. The last thing you want is a very high quality scope were the image jiggles around at the slightest touch or breeze. You can very quickly become frustrated.

- Get the best quality Mount AND Tripod you can afford
- Get the best quality Optics you can afford
- Get the best quality mechanical setup you can afford (ie structural rigidity/alignment, baffling etc)
- I would not try to choose a VISUAL scope based on Astrophotograhic images. Base your decision on real visual testing if you can.
- Go and watch other users setup and breakdown their systems at starparty events to gauge if this suits your circumstances.

Cheers

Originally Posted by ngcles

Pt 2 ...



I can't (and won't) tell you what to feel and if these are your feelings, a Newtonian is probably not for you and there is nothing wrong with that at all.



Don’t for a moment think I’m ridiculing your choice – I’m not. All I hope is that you choose for the right reasons. There are many reasons that make the Schmidt-Cassegrainian a legitimate choice for many people. No argument there at all. Going down that path because you hope for better visual planetary images is not one of them. Going down that path because you believe you are guaranteed higher quality optics … ditto. Some people also go down the S/C path because of peer-pressure or because they find them aesthetically pleasing (ie pretty). Personally I don’t buy telescopes to look at, but if that’s important to you as a buyer, well that’s your choice and I won’t argue about your feelings. Personally I choose a telescope based on what it’s like to look though, not look at!

Very best of luck with your choice and I sincerely hope that whatever you settle on, it will bring you many hours of observing pleasure.


Best,

Les D

[Satchmo]

What would I obtain if I wanted the best planetary instrument for visual use ?
I like to keep my feet on the ground so a quality motor driven premium 16" or 18" F4 Dob Newt with low profile focusser,well ventilated thin mirror, below 20% obstruction , and a 2X Televue Powermate plus Clave Plossl eyepiece , would be somewhere near the top , but below the 16" Apo refractor which I could never afford The larger aperture will yield a whole level of detail, via differentiation of colour in features by being able to maintain a healthy exit pupil for colour perception- regardless of the qulity of the seeing. An SCT would be near the bottom of my list of choices for all the reasons set out in this thread. A classical or dall -kirkham cassegrain would come in below the Newt as it has a faster aspheric primary, larger obstruction , and an extra optical surface .

[robz (Robert)]

Oh God................................ .............somebody kill me.................please?......... ......

I guess we all know the truth don't we?................but most are afraid to admit it(read on below), and some have secretly regretted upping their aperture because of the highly contageous ''A.F'', and have ended up with an expensive and possibly dissapointing giant bucket of fiddly glass and metal with the dreaded ''central obstruction'' and the contrast loss as a consequence?

Say what you like about the beloved newtonian, but I hate them........especially the long F ratio ones.........the ''cannons''.
I have owned real big ones and have an 8 inch now - as mentioned (you should see the obstruction on this one..........you can hardly see the primary through the draw tube!)..........no wonder my 60mm refractor can match it in the planetary department

As an Audiophile and having built my own amplifiers and speakers, the K.I.S.S. principle was no myth.It obviously also applies to the optical chain in a telescope doesn't it???

I now realise that large aperture may be of some benefit to see brighter fuzzies, but I have never seen a newtonian produce visual fine detail no matter how perfectly collimated, optically brilliant or cooled to within the required 0.5 degrees(!!!!)
I personally do not wish to at any time, set up the scope at breakfast or wait hours for the optics to cool down(fan assisted or not)....this is insanity.................surely?

K.I.S.S..........keep it simple stupid = REFRACTOR

[issdaol (Phil)]

Hi Robz,

Your initial request for information is an interesting contrast compared to your latest post on this thread.

You initially asked members of the forum for advice based on their experience with different scopes of different size, quality optics, design etc for planetay use.

A lot of members have posted some great comments and recommendations based on their experiences.

If you already had all of the sage experience and opinions in the first place (like your last post implies) why ask for help then put others systems, recommendations and opinions down???

I am sure we are all just trying to help give you the advice you initially requested.

Cheers

Originally Posted by robz

O.K guys, for as long as I can remember, I have allways wanted to be able to visually examine details in planets : the intricate structure of the belts and ovals on Jupiter and variations in the rings of Saturn.........bla, bla, bla,............you know what I mean

I am fully aware that seeing conditions play a big part in this particular field and know that some scopes need to be perfectly collimated/cooled down etc. to stand a chance at revealing any of the fine details I'm after.
I am also aware that what one sees through the eyepeice is not necessarily the same as what is captured and stacked with expensive astro cams and software.

After my last humorous and light hearted post, I thought I might ask for some honest opinions from those who have owned the many various scopes available to the amateur astrononer and are aware of the different performance levels and the reality of what to expect

The questions are as such :

does aperature still rule in revealing planetary details

How does a 12 inch SCT compare against a 12 inch or even a 16 inch dob at the same magnification Does the dob/newtonian need spectacular optics to begin to approach the SCT

Will a 4-5 inch good/medium quality(and price) APO or ED refractor cream all the above at the same magnification

Last of all, are high quality, small aperature(compared to the sizes mentioned above) refractors the ''ultimate'' for planetary viewing or is this just wishful thinking

Love to hear your thoughts

Rob.

Originally Posted by robz

Oh God................................ .............somebody kill me.................please?......... ......

I guess we all know the truth don't we?................but most are afraid to admit it(read on below), and some have secretly regretted upping their aperture because of the highly contageous ''A.F'', and have ended up with an expensive and possibly dissapointing giant bucket of fiddly glass and metal with the dreaded ''central obstruction'' and the contrast loss as a consequence?

Say what you like about the beloved newtonian, but I hate them........especially the long F ratio ones.........the ''cannons''.
I have owned real big ones and have an 8 inch now - as mentioned (you should see the obstruction on this one..........you can hardly see the primary through the draw tube!)..........no wonder my 60mm refractor can match it in the planetary department

As an Audiophile and having built my own amplifiers and speakers, the K.I.S.S. principle was no myth.It obviously also applies to the optical chain in a telescope doesn't it???

I now realise that large aperture may be of some benefit to see brighter fuzzies, but I have never seen a newtonian produce visual fine detail no matter how perfectly collimated, optically brilliant or cooled to within the required 0.5 degrees(!!!!)
I personally do not wish to at any time, set up the scope at breakfast or wait hours for the optics to cool down(fan assisted or not)....this is insanity.................surely?

K.I.S.S..........keep it simple stupid = REFRACTOR

[AstroJunk (Jonathan)]

Originally Posted by robz

Oh God................................ .............somebody kill me.................please?......... ......

Don't ya just love open debates!

Just remember, there is no such thing as the right scope - only the least wrong one.

Go and buy something BIG!

[Satchmo]

Originally Posted by robz

I now realise that large aperture may be of some benefit to see brighter fuzzies, but I have never seen a newtonian produce visual fine detail no matter how perfectly collimated, optically brilliant or cooled to within the required 0.5 degrees(!!!!)
K.I.S.S..........keep it simple stupid = REFRACTOR

Hmm , what can I say but you clearly haven't owned the right instrument or been hanging around with the right people at star parties and taking note of how and why they do things.

It takes a little care and know how to tease the finest planetary detail from the sky- don't expect to get it all just by slapping down a wad of cash on an instrument and just expecting it to perform . If you are happy to be limited in resolution by a small aperture then a refractor is a good choice, it will give all it is capable of, or just go and stick an off axis mask on a reflector and you'll hardly pick the difference. Any large instrument no matter the type will require care , patience and TLC to wring performance out of. That is how you actually see stuff far beyond the `slap down a wad of cash' approach.

You seem a little confused - yesterday you were singing the praises of SCT's as your ultimate planetary instrument, and today it's refractors ? Methinks you are having fun with us.

A lot of 'good oil' has been patiently sent your way in this thread by a number of people ..go read it and my advice is think twice before make posts seeking advice on "best instrument for *****" if you really have pre -conceived immutable ideas , refuse to take in any detail, creating a pile of traffic from people getting stressed that the detail not be glossed over with sweeping statements. Like the `boy who cried wolf' be careful that people who honestly tried to give their considered opinion will ignore you next time.

[robz (Robert)]

My sincere apologies to all and any that have been offended in some way by my last post. It was not meant as such in any way.

I was merely having a shot at myself in attempt at some dry humour as I indeed got so many faithful replies and assistance and good advice from all................so much so that it did my head in and the reality is that there is no perfect scope for all duties.

I guess that as mentioned by some during this discussion, the laws of physics can not be changed and they apply quite strongly in optics as they do in everything else.

All comments and replies on this thread were regarded as very useful information and a wake up call for me that I will need to make up my own mind on what I can afford and what I can handle physically.

Due to my failing health and my struggle with it over the years, it sometimes gets the better of me and dictates the extent of my ability to lift and move heavy items, causing frustration of body and mind.........such is life.

Best regards to all for your kind help.

Rob.

[robz (Robert)]

After careful consideration, I will be going for an 8 inch Maksutov or possibly the Russian 10 inch TAL 250K depending on total price including shipping (information pending at the moment).

[fuso (Anthony)]

I'm only a beginner, but i'm surprised no one has mentioned a mak

Plenty of astro buffs all over the world say a well made 6in mak is as good as a 4in APO.

After trying to get good views from my used 8in saxon dob, i'm saving for a mak( i'll keep the dob for the kids and DSO)

[AstroFlyer (Arek)]

Originally Posted by fuso

I'm only a beginner, but i'm surprised no one has mentioned a mak

Actually Mak was mentioned in couple of posts, eg post #8.
TAL-200K or TAL -250K would be a nice choice, as Robert discovered.

[AstroJunk (Jonathan)]

Originally Posted by fuso

Plenty of astro buffs all over the world say a well made 6in mak is as good as a 4in APO.

I would entirely agree, and there is a brilliant example for sale on this very forum at a great price

http://www.iceinspace.com.au/forum/s...ad.php?t=66455

[robz (Robert)]

Yes, the MAKs do have many advantages over the standard Cass.,R.C. or SCT.

They're not perfect either, but the advantage of a small central obstruction, long focal length and in the case of the two brands I'm considering, no mirror shift.

They are well known for their sharp APO like performance.

[Sylvain (Jon)]

I must say, Maks have my preference when it comes to planetary viewing.

[icytailmark (Mark)]

it really comes down to the seeing conditions etc. No point having a huge telescope if u cant use the high mag on planets. However if you have very good conditions it best to get the largest aperture u can afford. Reflectors gather in the most light therefore u see the most detail on planets.

[robz (Robert)]

Many people swear by their 4-5 inch APO refractors as the best for planetary viewing and claim ''high definition images''.

However this is no doubt inch for inch in aperture against other scope types.

I stated that I had settled on an 8 inch MAK as the scope of preference, but once again, I'm thinking twice before making the purchase as has been the same for SCT's after evaluating what has been said on this thread and Cloudy nights forum also.

So where do I go from here?

I wonder if a 16 inch dob would give me the occasional great view in good seeing and all other factors covered such as collimation, cooling etc.?

In a 60mm refractor at 175 x the moons of Jupiter are clearly defined ''disks'' and that's with a crappy SR eyepeice that came with it!

Can someone please confirm that a 16 inch dob can do this and more and not produce flared stars as moons, and can indeed show fine details on the planet's surface?

I am totally confused after so many opinions(the comments have been appreciated though) and am at the point where I am thinking of leaving amateur astronomy and selling off what I have before I even started back in to it again.

On top of that, I inadvertently got some members off side which is the furthest thing from my intentions when I started this thread, as I am not that kind of person.

All along, I only wanted to know what type/size optics are needed to visually see that detail when the seeing is right.

Rob.

[casstony]

Just go with your gut feeling Rob, most of the different telescope designs will give good views of planets: 5" refractor, 8" newt, 8" SCT(celestron edge with vents), 6" or 7" intes Maksutov Cassegrain(has very smooth, well figured optics and cooling fan).

The only thing I'd stress with a catadiotric scope is to get one with vents or vents and and fan, otherwise you might run into cooling problems. The Intes Maksutovs can be purchased with various focal ratios and secondary mirror sizes(eg. f15, 25% obstruction).

[issdaol (Phil)]

Hi Rob,

The main limiting factors for choosing a scope (apart from technical capability) basically come down to Size/Manouverability and Budget.

It sounds like you have some good experience already but I would recommend that you consider your Scope Budget and Scope Manouverabiliy needs and base your decision on the following:

- Get the best quality Mount AND Tripod you can afford
- Get the best quality Optics you can afford
- Get the best quality mechanical setup you can afford (ie structural rigidity/alignment, baffling etc)
- I would not try to choose a VISUAL scope based on Astrophotograhic images. Base your decision on real visual testing if you can.
- Go and watch other users setup and breakdown their systems at starparty events to gauge if this suits your circumstances.


At the moment I use my system 100% for Visual Work and I have always been a Visual Observer. I have yet to look through another system that provides better Visual Planetary and DSO contrast and detail. (I am not saying there are not equal or better ones out there but I would not like to think of the cost of those either )

There is another couple of members in Perth that each own both Tak APO's and Tak Mewlons. You may want to ask them and look though both.

If you can find a Visual Planetary scope of 4", 5" or 6" that is better than a Tak TSA120, TOA130 or TOA150 (or equivalent) then let us all know .

Cheers

Originally Posted by robz

Many people swear by their 4-5 inch APO refractors as the best for planetary viewing and claim ''high definition images''.

However this is no doubt inch for inch in aperture against other scope types.

I stated that I had settled on an 8 inch MAK as the scope of preference, but once again, I'm thinking twice before making the purchase as has been the same for SCT's after evaluating what has been said on this thread and Cloudy nights forum also.

So where do I go from here?

I wonder if a 16 inch dob would give me the occasional great view in good seeing and all other factors covered such as collimation, cooling etc.?

In a 60mm refractor at 175 x the moons of Jupiter are clearly defined ''disks'' and that's with a crappy SR eyepeice that came with it!

Can someone please confirm that a 16 inch dob can do this and more and not produce flared stars as moons, and can indeed show fine details on the planet's surface?

I am totally confused after so many opinions(the comments have been appreciated though) and am at the point where I am thinking of leaving amateur astronomy and selling off what I have before I even started back in to it again.

On top of that, I inadvertently got some members off side which is the furthest thing from my intentions when I started this thread, as I am not that kind of person.

All along, I only wanted to know what type/size optics are needed to visually see that detail when the seeing is right.

Rob.