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If I buy a Dobsonian, will I regret it?


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Hello all,

Firstly let me introduce myself. I am new and am sure glad to have discovered these forums (in fact they were discovered by my cousin). I have experience using my cousin's 150mm equatorial reflector but now looking to by a telescope myself.

I've got my eyes on the Skywatcher Skyliner 250PX Dobsonian. I think that's a lot of telescope for that money but I do have some concerns. I would like to look at the Moon, planets, galaxies, nebulae and other deep sky objects. Some objects are difficult for me to locate using the naked eye so I tend to use the setting circles of the equatorial mount a lot to locate them. Therefore, I am worried that if I do buy a dobsonian, I will not be able to locate the objects I want to look at and it will all be for nothing? Also, is it at all possible to track planets smoothly using a Dobsonian? I am able to do so manually (no motor drive) using the equatorial mount at magnifications up to 300X.

Also, my concenrs about the mounting aside what do you think of the Skywatcher Skyliner 250PX Dobsonian?

Many thanks in advance for your help,

Ralf

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I have one and I think it is great. For finding things I use an 8x50 right angled correct image finder which makes things really easy from a star atlas. I can track planets pretty easily by hand up to about 150x - any more than that is difficult but then again how often is the seeing good enough to go much higher?

collimation is very important as it is F4.8.

is is a hell of a lot of scope for the £££ :cool:

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You will not regret it at all.

because you are not buying electrics you get alot more aperture for your money.

You can add setting circles to the base for azimuth and a wixey for altitude. I personally think it's as accurate as a cheaper GEM mount.

With time and experience it's easy to nudge the scope to trackk objects.

I love mine and wouldn't go back unless it was for imaging purposes.

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NO!!!! You won't regret it!!!

The Skyliner range is a great brand - and is great value for the apeture. Working out the price for the component parts (crayford focusser, mirrors, eyepieces), it seems unbelievable that you can pick up an 8 incher for £270 approx. I was eyeing up the 250p myself - but ended up plumping for the 200p because of size, cost, etc. Haven't regretted it in the slightest.

I think you'll "know" whether a Dobbo is right for you. Why not go to your nearest Astro society or star party and speak to some of the guys there? I went to one recently and there was great variety among the 14 scopes there, from refractors to reflectors, and I was most drawn to the Newtonians on a Dobsonian mount (Dobsonian telescopes).

After looking at the paraphernalia of scopes, from GOTOs to hand powered, I knew a dobbo was right for me when I was watching a chap with his Dobsonian, move it to the relevant target, nudging to keep track...the simplicity really appealed to me, and after talking to him, I knew it was the right scope!

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Thank you all. I already feel I have a better understanding of Dobsonians. In addition to my initial queries I would like to clarify a few more points:

collimation is very important as it is F4.8.

-Does that mean that the scope is not callibrated 'out of the box'. How difficult would it be to collimate it (does it involve removing the mirror)? Will it need frequent adjustments/maintenance?

-How does 'nudging' compare to the slow motion controls of an equatorial? I know it must feel completely different but is it actually harder/less precise?

Thanks

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Ralf, to be serious.. collimation is easier than it sounds. ..and "nudging" is to my experience , like that which the pilots of Spitfires said of their beautiful machines..

you become as if one.. it goes where you want it to go by merely the thought..

p'haps over-eloquent but that's it.. not twirling a knob, but joining together like ballroom dancers. ...now whether your style is waltz or cha cha, that's up to you :cool:

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Your dobsonian should arrive in reasonably collimation but it is something you need to know how to adjust reasonably frequently to ensure you are getting the best out of the scope - especially with an F/4.7 scope. The 8" F/6 dobsonians are more forgiving in this respect but will still need the collimation adjusting from time to time. This actually applies to both newtonian and schmidt-cassegrain scopes.

Providing the motions on your scope are smooth, tracking with dobsonians soon becomes 2nd nature but it's never quite as simple as with an equatorial mount as you have to move the scope in altitude and azimuth to track wheras a properly setup EQ mount only has to move around the single right ascension axis.

John

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If I could only be sure that I don't need an equatorial mount...

If I were to buy an equatorial I would have to buy an 8" telescope (for £££ reasons obviously).

So you can understand my dilemma -- an equatorial mount or a larger aperture?

My main concerns are still locating difficult to spot objects and tracking planets (even Skywatcher themselves don't seem to recommend Dobsonians for planetary viewing!)

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With more aperture you will find it alot easier to locate and see DSO's.

IMO setting circles on the cheaper GEM mounts are very unreliable. My advice would be get as much aperture you can afford and carry around and store easily. A red torch and map and learn your way around by star hopping. You will soon discover many of the main Messier objects this way.

Then adapt your dob in a similar fashion to what I have done see link below.

http://stargazerslounge.com/diy-astronomer/79817-my-dob-degree-circle-modification.html

This will enable you to find harder objects. You will be amazed at how accurate this type of setting circlle can be.

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A dob has many advantages as others have said. To me, the greatest advantage is you can set it up in no time and be observing straight away (if you store it at ambient temperature).

Collimation is simple with a laser collimator but many prefer cheshires and reckon it is just as easy.

If you are worried about finding DSOs, you could buy one of these ... Astro-Fix Locator - you need something that tells you the current alt-az coordinates (how much to point it up and in which direction) - I use an old PDA running Astromist.

Get the dob, you won't regret it.

Mike

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I love the concept of getting involved with the whole "where is that object in the sky? " thing. Of course, GOTO is better / more convenient for imaging and other types of observing but you will not regret your time with a dobsonian

Nudging isn't so bad either and what is more, there is a lot more bang for your buck.

I found collimation to be worringly easy see here for report but in any case, you can always practise until you get it perfect

Good luck

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I also have a 250PX and yes I do pine after my manual fine adjustment controls but then I think hey with my 6 inch I could not see this galaxy so on balance I am happier with the 10 inch....Now a 12 inch with an equatoral mount?

Mark

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I got the 250px and i love it. As mentioned it's so easy to set up. Cool down is not very long. I have enjoyed looking at the moon and planets up to now. Even managed some webcam of planets through it.

You won't regret it if you get one.

Brian

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hi,

I had a 250px dobs and the optics were excellent, they always seem to be recommended in whatever I read and all my beginners astronomy books always recommend a largish aperture dobs to start with.

However, I hate to go against the common concensus and this is only my experience, but I didn't really enjoy the dobs mount. It may just be down to my expectations, time available (kids!), patience, being more into technology and my local sky conditions, but I found I was quickly wanting a mount that tracked the objects I was looking at as I enjoy staring at them for a long time and moving the dobs by hand just made them jump around. I also quickly got interested in taking photos and images of objects. I found star hopping and finding stuff difficult too and struggled to look at a star chart, then the eyepiece whilst trying to track what it was pointing at.

I now have a small refractor or Mak-Cass on a simple GOTO mount which I enjoy controlling with sky mapping software on a laptop and viewing the image with a sensitive camera or photographing with a DSLR.

Just my opinion as I say, the 250px is very well recommended by most people.

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I think (re. above) it is rather good that a circumspect(?) view is presented, just occasionally. I have NEVER used a Dobsonian, in practice, but the idea of "nudging" (jerking?) doesn't fill me with supreme confidence. By (perhaps) some analogy, I never find the "silky smooth" Giro III all that easy to use either. The idea of an Alt-Az mount does have immediate intuitive appeal for me. But, thus far, the easiest thing to use, I have found, has been my old EQ3-2 turned on it's side (to function as a Alt-Az). The manual gears plus flexible drives still seems more "positive" than nudging. :)

Perhaps one would have to see an "expert in the field" in action. I am entirely willing to accept the SKILL factor comes in... But I see now e.g. the Skywatcher Dobsonians come with GoTo, these days! My ideal (maybe they achieve this?) is that one could "disconnect" ANY drive or gear system and do things manually (or automatically!) according to choice. :cool:

P.S. The last is a semi-serious question though. Can you use these "driven" Dobs in "manual" mode?

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I've followed Saturn at 470x with my 12" Dob. Remember that planets are best observed when they are in the south and at that position the drift is purely horizontal, the altitude is moderate and that gives you nice leverage on the tube.

It's harder finding DSOs without GoTo. But you get to learn the sky and find things on the way that you'd have missed otherwise. I have yet to try a correct image optical finder but I'm hoping that it would fix this problem (or upgrade my red-dot x1 finder with a telrad).

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I bought my 250px a couple years ago and I will say that the optics and build are fantasitic. On arrival, collimation was bang on and I've found I dont need to touch collimation for at least 4-5 months at a time (this all depends on how much u intend to travel with it or move it I guess). The 10" of aperture allows the scope to perform incredibly on everything from faint galaxies to planets and doubles. I was most especially surprised with its clarity on tight doubles. Splits the double double with ease at high mags.

As for the dob design.. you cant have everything and yes, the nudging is not the easiest of tasks at high magnification if you are used to EQ mounted scopes. On the flip side, its simply magical being able to just plonk the scope on the ground and instantly have 10" of mirror at your fingertips. When viewing larger objects at lower mags, the nudging doesn't cause me any hassle at all (and this scope rocks at lower mags). I will admit that I did get an EQ6 Pro 6 months later which turned it in to my DREAM SCOPE! (but I am pathetically weak at resisting my desire for kit lol) The only niggle being the height of the eyepeice at certain directions when mounted.

In short, THIS BEAST ROCKS, you wont be disappointed!

Matt

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There are thousands of happy dobsonian users (and I'm one of them). I've tried setting circles and GOTO and I prefer a dob. Simple design, simple set up, maximum aperture for money.

It doesn't suit everyone.

My interest is visual deep-sky from dark sites. I occasionally look at Moon and planets, more so when I was starting out, but these days not often. So aperture is everything for me, plus simplicity because I want something I can easily transport, put up in a field, and quickly take down again when the clouds roll over.

The dob works fine for planets but if I were going to be doing more planetary than deep-sky then I'd probably think of other options - I wouldn't need 10 or more inches of aperture, for one thing. 8 or less would do. And I might prefer a tracking mount.

Also think of the sky it's going to be used under. For satisfactory deep-sky work you really want to be able to see the Milky Way with the naked eye. If you can't see it from your garden then you might need to drive some place where you can. It's certainly possible to see the brightest deep-sky objects in light-polluted skies but finding them with a dob can be frustrating, due to the lack of visible stars to hop to. In a seriously light-polluted environment (e.g. where the stars of Ursa Minor can't be seen) it's not going to be much fun, and lunar/planetary/double-star observation will be more rewarding.

It's the usual story - decide what job you want to do, then get the right tools for it.

As for collimation, it should be fine out of the box. Don't worry about collimation for at least a year - concentrate on more interesting stuff i.e. using the scope. Then get the right tool (a Cheshire/sight-tube) and you'll find it no hassle at all.

Andrew

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After reading all the opinion I have come to the conlusion that a Dobsonian will serve me well.

As I've mentioned before the Skywatcher Skyliner 250PX is the one I've got my eyes on. I believe this is value for money without compromising quality. However any further suggestions are still welcome.

(The Meade lightbridge 10" is another alternative. Its more expensive possibly due to its truss design but does it deliver better quality?)

Many thanks to all who responded to this thread.

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Truss design delivers greater portability, not necessarily greater quality.

The mirrors for Meade and Skywatcher come from the same place (in China).

If you can manage the weight and bulk of a solid tube then it's a better bet.

The Skywatcher sounds like what you want - I'm sure you wont regret it.

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I found the more you think about things the harder the choice becomes.

Just get it :cool:

Thanks. I will be getting it in the very near future and the Skywatcher definitely seems to be the one to go with. But the posts here definitely made the decision making process much easier.

Thanks again everybody!

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