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MJP

Help I'm confused

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I have a Celestron Omni 120mm refractor on a manual CG4 mount and also 80mm Viven on a mini port - a-mount (for grab and go). I regularly go to a dark sky site a few miles from home.

I am thinking of getting a Skywatcher HEQ5 Pro Synscan go to mount because from my light polluted garden I often cannot see enough stars to star hop.

Then again for the same money I could get a skyliner 200p flex tube dob with GoTo. I assume the dob would be better for deep sky than my refractor which I could use for lunar and planetary. Is this right?

I have no experience of dobs and am not sure if the GoTo works and how easy they're to transport. Is collimating a problem and is it needed frequently ? Would the 200p give me reasonable access to deep sky objects?

Basically I am confused as to which route to take. My interest is in the planets but also messier objects etc.

Any advice, views etc. will be appreciated.

Mike

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How long have you been doing astronomy?

I ask as it half seems that you are jumping from one scope to another with the hope that one will suddenly reveal everything.

The 120 is a reasonable size so at a darkish site should show a lot of Messiers, the manual mount means you will not be able to track easily and the absence of goto means you have to locate the objects.

I look at a fair selection of Messiers from the town I am in with a small 70mm, a set of 42mm binoculars reveal quite a few as well.

A 200P will reveal more DSO's, that is what a bigger objective enables, you would get an increase of 277% light collection. With the response of the eye that would mean about an additional magnitude.

A 200P is reckoned to be about the largest to be reasonably transportable. For goto you will need power of some sort where it is to be used.

Collimation, basically something to be learnt, not impossible otherwise another method would have to be found. Read up and figure it out during daylight.

Edited by Capricorn

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the 200p will be a good scope for DSO's and the 8 inch dob is a fav for many deep sky enthusiasts.

I have to be honest, I don't have any experience of goto dob's but I'm sure you'll need a power supply as already stated above.

Collimation is not difficult or scary and isn't required as often as to be a chore.

What budget are you thinking of?

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I have the skywatcher 200p flextube dobsonian goto. i managed to pick mine up second hand for £450. I believe they are about £750 new. You will need a power supply i recommend a 17ah one, can be picked up from maplins, i owned a 7ah supply once and it only lasted one night :) (heavy session) collimation is easy once you have done it a few times, i recommend a cheshire collimator as laser colimaters can be out of collimation themselves unless you spend quite alot of money on them, to be honest a cheshire collimator is fine in my opinion. The dobsonian goto is not very good at long exposure photography due to field rotation, The goto will track objects across across the sky but does not allow for rotation, fine for a few minutes maybe for planetary but not for longer exposure dso. In terms of transport the scope and mount will fit fine in a hatchback type car with the main tube across the back seats and the base in the boot . A ford focus size car is plenty big enough. The skywatcher 200p flextube is a great scope im very happy with mine i have seen loads of dso`s and i am very happy. I would say get a light shroud and dew sheild to help reduce light pollution to use even at a dark site. A common recomendation is to buy a camping mat and to make your own, it should only cost a few quid and be fairly easy if you measure up first. good luck and clear skies.

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Thanks for the comments.

I've been doing astronomy for nearly three years. My dilemma is wether to spend the money on a GoTo mount for my current scope or go for a dob. Both will cost about the same. It's a question of which is the best use of scarce resources!

Mike

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I used to have the same scope and my prediction is this. if you buy the 200mm dob, you'll almost certainly never use the refractor again. personally, I'd prefer a little more aperture which you could get if you went with a manual solid tube scope. perhaps this http://www.firstlightoptics.com/dobsonians/skywatcher-skyliner-250px-dobsonian.html along with a Telrad, star map, right angle correct image finder and a couple of eyepieces within your stated budget.

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If you have access to a dark sky site then the 200P dob could really show you some things !

The GOTO mount will point your 120mm refractor at those same deep sky objects of course but the views of them won't be as satisfying as the larger aperture dobsonian. The good thing is that the 200P dob is an F/6 so rather good on the Moon and planets too as well as being easier to keep in collimation.

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My dilemma is wether to spend the money on a GoTo mount for my current scope or go for a dob.

If it were me, Mike, I'd try to work out how and why I wanted to use the given telescope in relation to my budget.

For example, for visual work, I'd want to use a manual telescope, that way I'd be learning the sky whilst hunting out DSOs and star hopping. Within my budget, I'd be plumping for a decent refractor or as large a reflector as possible. By not having GoTo, I'd spend that extra cash on increasing the quality of my optics or aperture.

On the other hand, if I fancied making some photos, I'd probably be looking at a really nice mount and in the best of possible worlds, a mount with GoTo. That way, I'd have a decent tracking system from which to make my photo-shots and with the added GoTo, I'd also have a quick way of maximising my visual observing time without having to bother with star hopping and the such.

Hope this helps a little :icon_scratch:

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it's so easy for us all to spend your money too of course. good advice above. I'd assumed visual only observing of course.

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Unless you are interested in imaging I'd go for the Dob. The frac on the guided EQ will be better for imaging but will not have the light grasp to amaze you visually whereas the Dob will be fab at DSO's under a dark sky in particular. :grin:

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