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Narrowing it down to 2 ??

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Hi all,

After some debate in a few scopes theads i think i may have finally narrowed my search down to a final choice, so a few opinions would be welcomed thank you kindly.

Just to be clear, my main objectives are

1.Portability

2.Apeture

3.Cost

My main interests are eyeball to eyepiece practical viewing with little to no astroimaging interest. My in main subjects are planets, moon and the most popular observable DSO.

I started out being interested in the SkyWatcher 127 mak and after many upgrades and decisions later i headed for a large 9.25 Evo but this turned out to be not what i had in mind

for a self sufficient scope so then pondered the dream scope of the 11"CPC GPS

But......

After looking over the FLO site for some day now i am back in the SkyWatcher camp and i am very interested in the 12" Flexi-Tube GOTO Dob....so opinions are needed on a few issues please.

Firstly i looked at some user pics of the main planets and the dob for me was every bit as good as the 11" SCT considering it is over a £1000 pound cheaper !! i would want £1000's worth of

considerably better quality image for the money so this is why i can see more cons then pros for the SCT

Cons.

1 Cost

2 Dew heater issues

3 Extra wires for above

4 Narrow field of view

5 Needs power to use it

Pros.

1 Quality brand

2 ?

The 12" Flexi Tube GOTO

Cons.

1 optics re coating at some point

2 supplied ep's are apparently sub standard ?

Pros.

1 Cost

2 Not a dew magnet

3 Great all rounder for views

4 Doesn’t need power to use manually

5 No wires on floor with right battery sat on base

Both scopes have dual encoder tech and both are at opposite ends of the scale.

I think i have pretty much talked myself into the dob but something about Celestron keeps tapping me on my shoulder so to speak.

Whats your thoughts peeps...you lot use these night after night so i really need to get this right, i would hate wishing i got something else.

Have i missed any crucial factors?

I wouldn't be even concidering the dob if it wasn't for the fact that just googling jupiter or saturn thought it didnt leave me gob smacked !!!

Even though the SCT is technically a better planetary scope the dob really does pack a punch that, well, i cant tell the difference, added to

that, that the Newt loves DSO it appears to be a no brainer.

Or am i wrong ? please help peeps.

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Why do you think the SCT is a better planetary scope? The Newtonian is probably better on axis as it has a smaller obstruction and larger aperture. Off axis, the SCT probably has the advantage.

But if you get the GOTO version, it tracks the planets for you, and you don't care about off-axis performance.

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Its just what a few opinions were thrown at me on different threads Ags ;)  As i am still a noob on this tech can you explain this on and off axis thing you mention please.

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Hi lee,

With longer focal lengths and slower f ratios I would agree that the sct would be a better planetary scope by giving a high mag for a given eyepiece and with higher f ratios it requires less expensive eyepieces.

For visual and dso work I would say the dob is a better scope as a bigger aperture can be bought for the same price and focal lengths tend to be shorter for the same aperture meaning a bigger slice of sky can be seen in the eyepeice. Doing away with goto qnd tracking can save a considerable qmount of money meaning an even bigger aperture is in reach. One issue though is an f5 dob will benefit from better eyepieces than an f10 sct but a good set of eyepieces will be with you for years anyway meaning this isnt always an issue.

Cheers

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On axis = in the middle of the field of view.

Off axis = off to the side. The dob shows more coma here than the SCT, so the view degrades.

I would say you can easily get to high magnifications with the dob. The SCT's long focal length is only a disadvantage.

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Thanks all....so it looks like the dob will need a decent set of ep's then. I think 3 will be adequate for my needs. A star splitter / planet one..A mid range and a wide field. I will check out other users range but any ep's of choice to look for ?

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Lol because I'm a big strong lad and these two scope are at the max level of portability regarding aperture for me

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As for dew control this is something you would eventually want to consider with the dob as the secondary mirrror is prone to dew although not as much as the corrector plate of an sct. A simple 12v hairdryer can be used or you can get more elaborate and integrate a heater pad behind the mirror.

Dobs are excellent visual scopes for deep sky work often due to their simplicity and the ability to get a bigger mirror for the same money. With an sct the mounts are more complex and often account for a significant chunk of the cost.

For eyepieces, for the dob there are a number of options but i would tend to buy a good set from the start as eventually people trade up over time anyway and eyepieces like televue have strong resale prices meaning you can often recover approx 60% of their new price if you decide to sell. Alternatively the es82 range have had good reports too and are well regarded.

As a dob fan ive never really used an sct much but ive often been tempted by the celestron c9.25 xlt paired with a skywatcher as-eq6gt mount. Ive seen this combo in use before and was impressed.

Cheers

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Hi Lee,

I think you are definitely going in the right direction with a Newtonian design, they offer the best value for money going and have excellent performance and cooldown properties.

The coatings in my first Newtonian lasted 20 years - modern coatings probably last longer if looked after.

You will need to choose good eyepieces to match the scopes high performance, I would suggest good quality eyepieces with a wide field and good eye relief - Pentax XW's, Vixen LVW's are two good makes - not cheap but they will last a lifetime.

The only downside of Newtonians is that viewing can get uncomfortable as the eyepiece ends up at all sorts of angles - this is where the SCT design excels as you can view comfortably from the rear whilst sitting down - but you pay a lor more money for them.....

Hope that helps

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The only downside of Newtonians is that viewing can get uncomfortable as the eyepiece ends up at all sorts of angles - this is where the SCT design excels as you can view comfortably from the rear whilst sitting down - but you pay a lor more money for them.....

Include a good observers chair for comfortable and ergonomic observing, much of the time your posture will involve perching rather than sitting. Include also the light shroud for the 12" flextube. Are you completely set on the goto version? The manual version is excellent; easy and smooth to operate, lighter and will save money, which you will need for good eyepieces - consider purchasing used. The 12" flextube is portable. I used to have an 8" SCT, which provided great planetary views, my former 12" flextube and current 8" dob have each provided even better planetary views.  

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The Pentax eyepieces are very nice, probably the best buy for the money if you're looking for quality.

My 8SE SCT is annoyingly awkward and heavy to set up once I've lugged the NEQ6 mount out, but it does give tremendous views of the lunar surface.  My NEQ6 could no doubt handle an equivalent Newtonian scope, I have yet to try anything else on it.

A Dob mount for the sizes you're talking will still be large, bulky, and quite hefty once the battery for Goto is taken into consideration, and there will be wires too.  Some nights you may also get fogging on your eyepiece as well as mirrors so you may need that dew heater / hair dryer after all (wires!)  A 12" Newtonian isn't exactly small either so safe storage space should be a consideration.  I don't have much in the way of space, the NEQ6 tripod and mount stand in quite a small floor space once the legs are gathered together, the OTAs live in large plastic tubs (using the original packing foam), I doubt there will be a plastic tub large enough for a 12" Newtonian so either stand it on its end or make your own coffin-sized case!

Edited by jonathan

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I would like to get a large newtonian myself, but i would not dare go above 10" for weight & size considerations. I don't know if 10" counts as a large dob these days  :laugh:

Edited by Ags

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Hi lee,

If you are located in east yorkshire then check out the Scarborough and rydale astronomicql society. They are a good bunch who do active observing sessions, often from dalby forest , and they organise the dalby starfest every year. They may be able to give you a demo of some of the scopes you are considering and Andy Exton from the club is often here on SGL.

Cheers

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That's great info Astronymonkey ;) i live east of Hull and the sky if full of light but an hour up the road at Wharram Percy there is an off road track to the medieval village and its pretty dark there...not too far from Dalby :p thanks matey i will check them out.

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For what it's worth, I think that it's hard to beat an 8" or 10" dob. However, I wouldn't bother with GOTO unless I were doing astrophotography with an Equatorial mount. I don't like the idea of needing electrickery in the middle of nowhere, and at start parties I've heard plenty of wails as power tanks ran dry, or scopes slewed and unplugged themselves. To me, the manual simplicity of a normal dobsonian is a think of wonder.

My 10" fits across the back seat of my car (just!). If thinking of a 12", a flex tube would be a good idea if transporting around.

+1 for the hairdryer idea. I've got a wee one that you can plug into the car. I've only had to use it a few times, though; I don't find that the secondary dews up that much on my solid tube. The flex tube might be worse, though.

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Thanks Andy for the input, i do like the idea of a goto in the sense that once the moon,Jupiter of even a close double is in there at a nice high mag 'seeing allowed', its nice to not have to nudge nudge nudge and let it just track,

I am familiar with the sky still even though its been a while and finding things isnt that much of a necessity for the goto aspect, its more the convenience of it tacking but that said i am sure there will be times i just cant find that object and then the goto will be there as my aid ;)

The power side of things is not so much an issue either as i can get one of these :-

http://www.firstlightoptics.com/batteries-powerpacks/tracer-12v-14ah-lithium-polymer-battery-pack.html

And it just sits nice on the mount so no trailing wires, plus the 300p FlexTube GOTO knows where the wires are according to one review and will slew the opposite way when it knows it too close, that along with the dual encoder system allowing the manual

movement of the unit to alleviate slewing time before letting the scope finish the target lock just all sounds blooming ace to me lol

I will however take yours and others advice on the hair dryer, i will also make a carbon fibre tube shield once i have the dimensions to eliminate stray light and to protect that secondary. When the time comes i will post some pics of how i will make this.

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Yeah, it is a personal preference thing, and yes, I tend not to push the magnification that high, so tracking it's such a thing.

I did spend quite some time looking at secondary heaters and things, but to be honest, unless you're going for a really big scope, there's not much that fits, while small hair dryers are pretty cheap...

For the hairdryer I have to run mine from my running car. I'm not sure that a Tracer battery can supply the current (I'm no sure what their maximum current is - worth checking)

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I guess after choosing the EP's Andy i will be sourcing a 12v Dryer then eh lol ;)

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Hi, I have the10" SW which I would highly recommend. Fitted with a set of wheels / castors it is easily rolled out and the viewing position is just right for an old office chair on castors. This gives me a quick and comfortable setup which means I get to use the scope more.

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Mmmmm just when i thought i had pretty much found my perfect dob i find this :-

http://uk.telescope.com/Telescopes/Dobsonian-Telescopes/Truss-Tube-Dobsonians/Orion-SkyQuest-XX12g-GoTo-Truss-Tube-Dobsonian-Telescope/pc/1306/c/1316/sc/1355/p/109971.uts?refineByCategoryId=1355#tabs

This appears to be pretty much exactly the same as the Skywatcher 300p FlexTube GOTO except the Orion one definitely has a more rigid construction and i better focuser, there are better ep's on offer as standard and

a few other little gadgets, so i guess its down to mirror quality ?

I have emailed SW asking what the wavelength of their optics are (still waiting) but i have no idea about the quality on Orions mirrors, reviews are mixed although the Orion unit looks the better quality of the two !!

Any one out there with experience of this Orion scope ?

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