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Fypunky

Honest Dobbie opinion please

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Hello intelligent people of the astro world.

I have put this here because although I have been observing a couple of years now I still class myself as an equiptment newbie.

So as mentioned I have been observing the stars using our (was my daughters first scope, I have now adopted it) 130eq astromaster, I updated the mount with a Synscan GoTo which has given us soooo much more pleasure observing. I am about to update the ep's going for the Celestron x cel range 12mm & 7mm with a x cel barlow 2x just to improve the image we see over the stock/ cheaper ones we bought when we first started.

So, this is where you lot come into it, I am at the start of thinking of buying a Dobbie, I am thinking 10in, I am currently in love with doubles, the view, the physics, the whole thing. Galaxies, nebs and DSO's I love to view, all of which is done mainly at mid/ low mag, I know the 10in will give me 4x the light gathering of the current scope, read all the info and propoganda from various companies however they never ever tell us the bad points!

So may I ask for your opinons please, I wont be going for a goto version, it will be driven by hand which I figure at low/ mid mag wont be an issue tracking the object.

What downfalls are there?

Any negative points?

I am guessing that the new EPs (1.25)  will be ok in it, no mentions of any probs with them.

SO what I am trying to achieve is you talking me into taking the plunge lol (also like the idea of sitting down looking through the EP) This started because sometime ago we went a long to an observation night with the local astro club, one chap had a hubble on a tripod! I did my upmost not to look into it because I knew the second my eyes focused on a target, I would look at mine and go mmmmm, unfortunatley M13 was in the EP, at a dark site, the rest they say is history! Would a 10in resolve most of the stars say in M13 with the said EPs, dont want to spend a few hundred quid to find the image is just a bigger fuzz ball than the 130eq?

Shall I start to start to plan the money laundering ready for purchasing? Oh and one last thing, any ideas on the best way to hide it from the Mrs should I get one?

 

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No comparison with a 10" Dob and a 130mm Astromaster. Apart from extra dimensions and weight, everything will be better with the 10". It will definitely resolve globular clusters into stars.  :icon_biggrin:

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A 10" dob is certainly a very capable scope. They are faster than the 8" at f4.7 so can be more demanding on wide field eyepieces.

If collimated and cooled properly then you will get good performance on doubles, although obviously you will still have diffraction spikes.

M13 looks better with more aperture, with a 10" under a dark sky you should certainly resolve deep in towards the core and should be able see the Propeller feature for instance.

The 7mm should give an excellent highish power for planets and globs at x171 (assuming 1200mm focal length). You may want something in between too but see how you go.

Just make sure you are comfortable with the size and weight. The Skywatchers are quite a bit heavier than Orion optics for instance, but also significantly cheaper!

As for hiding from the Mrs.... err, perhaps stand it in the corner with a table cloth over it and pretend it's a new piece of furniture? ;) 

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Other than loss of goto (which, depending on light pollution is not really a major issue, more an excuse to learn your way around) and having to nudge on planets at high mag, I honestly can't think of a real drawback. You will definitely get much better views in a 10 inch than a 130mm. M13 will be a mixture of fuzz and resolved stars, but on a good night with high-ish magnification you will get a lot of resolved stars. I find open clusters benefit a lot as well - the double cluster is miles better in my 8 inch than in the 130p.

The Ex-Cels are good eyepieces. If you are buying two I would say go for the 18mm and 12mm, as these will be great for DSOs (I think the 18mm is the pick of the bunch in the Ex-Cel). Not to say you won't get use from the 7mm, but I'd still buy the 9 and the 25 before it.

Not saying what you should or should not do, but not buying a 10 inch Dob right now will make you a bad person and you will regret it for the rest of your life :)

Billy.

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Only real drawback is weight and size. If you can manage that, it's hard to beat a dob for the money. I kind of wish I had something for astrophotography, but what would I look at while my telescope is tied up taking pictures?

GoTo is certainly nice, but not absolutely necessary. Sometimes it's more hassle than it's worth. It actually took me over an hour to get mine aligned last weekend because we had so many clouds. Everytime I would try and get on a star, large clouds would move in so I'd have to start the alignment on a different star, and repeat ad nauseam. I should have just moved it manually for the evening and been done with it. We were mostly there to look at the full moon for the event anyway, but I wanted to see other stuff while the moon was covered so I wanted to hop around as quickly as I could.

I have a 12" and use 1.25" eyepieces for my shorter focal lengths all the time. You don't really have much choice when you want to push the magnification. I can resolve the stars in M13 with mine just fine and I imagine you should be able to in a 10" as well, they'll just be a bit dimmer. M13 is fairly bright under dark skies and has sort of a bluish hue to my eye.

Edited by Buzzard75

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First of all, many thanks for helping me to spend money :headbang:

Its good to hear honest views from people who have the experience and the knoweledge. My plan is still to use the 130eq for various occasions, like if we are away in the caravan and solar viewing as we built a solar cap for it and of course my daughter can still join me so we are not taking turns ( tho I can see me ended up with the 130 and she will be on the dobbie).

I didn't mention we did update to some decent lower mag EP's for open clusters like my fave the Beehive so at that end we are good, its just the mid to highish end to complete it and a decent barlow.

I knew it would be so much better viewing to a point, tasted the fruit but wasn't sure if there would be anything that would make me think twice or wish I hadn't after I had bought it.

Again many thanks

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Yes, moving from a 130mm to a 10" will make a striking difference on deep-sky objects, as others have written.

Lots of people like Dobs, and they certainly offer large aperture at low cost.

I would caution however that I found that moving from a 127mm GoTo to a 203mm manual scope was a most disagreeable experience. I just couldn't find anything with it unless it was near a star pattern I could pick up in the finder, and locating anything near the zenith with a straight-through finder was impossible. I struggled with it for a couple of months before looking for a kit with the same aperture, but with GoTo.   For me, the C8 SE (a 203mm SCT on a GoTo mount), was the right choice. 

I added the Starsense, which is not necessary but takes all the fiddly work out of setting up and, as I proved the other night, works even with  substantial cloud scudding over the sky.

If you have not yet upgraded your eyepieces, you may be pleasantly surprised at the difference that replacing the kit eyepieces makes to the view.

 

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Someone I was speaking to went to kelling with his 12 inch dob...but pitched next to him was someone with something stupid like a 30inch..he climbed up the stepladder to have a view and m13 shone so bright it took his adaptive night vision away!!

He now never takes his scope!!

10 inch is nice..12inch isn't that much bigger..oh look they do a 16inch too!

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I have a second hand 10" Revelation (F5) which I mainly use for outreach, and it's the best £250 I ever spent. To address a few points:

- Weight-wise, 10" is pretty manageable even if it is stock Chinese engineering rather than some lightweight model. I move mine in two parts from garage to car and lug it from car to observing location single handed regularly. Making up a wooden skate with four old furniture castors is a good idea as you can then roll the whole unit from A-B as needed.  I think 12" is where it starts to become harder to manage. Our society 16" goto Dob has to be moved in two parts and it is a 2.5 person job for each part with a real risk of putting your back out or dropping it.

- Eyepiece wise, I tend to use mine mainly with a Baader Mk IV zoom (8-24mm). It's not the finest quality view but being able to use the whole scope as a giant finder at 24mm and then zoom in as needed is very handy. By the time you've found a target with a wide eyepiece and then switched to a tighter one for a close-up it will have drifted some way and probably need finding again, assuming you don't nudge the Dob in the process.

- I also have a cheap widefield 32mm 2" eyepiece - it really works well for finding faint stuff but you do get a dark spot in the centre of the FOV which is obvious on brighter targets like the moon as it's not really that suited to the scope.

- Straight through finders tend to be a bit of a pain as they are low down and close to the tube at low elevations, and almost impossible to look through at high elevations. So budget for a RACI finder.  Better yet, I just don't use a finder at all - I've fitted a green laser rifle sight to the metal tube and just use that to figure out where I'm pointing. With a bit of practice and the Baader at low-mid power, I can literally flick the laser on, swing the Dob to the target by eye and have it straight in the eyepiece for a lot of targets.

- You'll need a colimation tool of some sort. I just use one of the 20 quid cheap lasers from Amazon/eBay. You do have to dig the rubber sealant out of the adjustment screws and build a jig to colimate the colimator when you receive it, but it performs very well thereafter - about 30 seconds to recolimate the Dob after moving it in the car.  A couple of weeks back I had the chance to compare my properly collimated 10" vs the uncollimated collapsible 16" goto skywatcher Dob on the Moon. The latter was a blurry mess vs. pin-sharp views in mine, so don't skip this step.

- Once set up properly and with the right eyepeice, the views are fantastic. Even the faint fuzzies are bright against moderately LP skies. Using the laser to manually track the ISS I managed to give four people (including me) views that clearly showed the solar panels and main body of the station in a single 3 minute pass, and that was with having to dodge a fair bit of cloud cover to boot.

Go for it!

 

Edited by IanL
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I started with a 150P on a manual equatorial mount, which was great. I then moved to a 8" GOTO Dob and the difference is substantial. Talking of M13, this changed from a bright fuzzy blob to a ball of resolvable stars, not right to the centre but far better. Using the GOTO I found really easy and very accurate. For me I definitely made the right choice but the choice and use of scopes is a personal thing.

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Again for the time to rely, this has brought a new question if I may.

We talk about weight, so.. Would you say the best is a solid tube or the collapsible pipe type?

I assume to the view is the same (once colimated)

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21 minutes ago, Fypunky said:

Again for the time to rely, this has brought a new question if I may.

We talk about weight, so.. Would you say the best is a solid tube or the collapsible pipe type?

I assume to the view is the same (once colimated)

The optics are the same. The flextube ones actually weigh a little more than the solid tube ones but do have the advantage of the collapsible tube for storage and transport. You may well find that you need to get a light shroud if you go for the Flextube to stop stray light and dust getting into the light path and onto the mirror.

 

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27 minutes ago, Fypunky said:

Again for the time to rely, this has brought a new question if I may.

We talk about weight, so.. Would you say the best is a solid tube or the collapsible pipe type?

I assume to the view is the same (once colimated)

I concur with John. A 10" flextube removes about 1/3rd of the thin rolled steel tube but to replace it you need to add the three extending tubes plus a pair of mountings which are actually much heavier than what was removed. The only benefit is storage and transport, since the tube collapses down to about half its original length.  In terms of cost, you're going to pay about £100 more for a flextube type vs a solid tube.  Only worth it if you are planning to go out to dark sky sites and need to save space to fit it in your vehicle.

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Ok thats it, cheers guys, decesion made.

Will have a look at some scopes when I nip to purchase the new EP's, then work out my masterplan in purchasing said item.

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13 minutes ago, Fypunky said:

Astronomy assistant to my daughter...

 

http://liviastronomy.weebly.com/  My daughters web site

My daughter used to love coming out to observe with me or to go to star parties with me around your daughter's current age.  She's now an electrical engineer working on computer design.  Good luck to you two and keep encouraging her STEM interests.

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At the moment she is set on Architecture! 7 years at uni, best get this Dobbie bought sharpish.

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I've a solid tube 250px: great scope :thumbsup:

It will show you loads!!  I use 24mm, 13mm and 7mm 1.25" EPs with it.

My one holds collimation ridiculously well.

At high powers, there can be a little overshoot as you move and track: but there are many suggestions out there for smoothing the motions.

A Telrad is a top accessory!

Best of luck,

-Niall

 

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Scope is going tio be fast, f/4.7 I guess and so you may need to add a coma corrector, likely subjective but I would say that if you looked through one with one then yours without then you would want one. Suspect that seeing more but seeing them worse is not the intention.

Also if f/4.7 that could mean better eyepieces then the X-Cel range - I actually presume you mean X-Cel LX. The non-LX's are poor. I get the impression that faster then f/5 they do not hold up perfectly. There is no specific value but things just start to get not so good.

So take those into possible account.

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16 minutes ago, ronin said:

Scope is going tio be fast, f/4.7 I guess and so you may need to add a coma corrector, likely subjective but I would say that if you looked through one with one then yours without then you would want one. Suspect that seeing more but seeing them worse is not the intention.

Also if f/4.7 that could mean better eyepieces then the X-Cel range - I actually presume you mean X-Cel LX. The non-LX's are poor. I get the impression that faster then f/5 they do not hold up perfectly. There is no specific value but things just start to get not so good.

So take those into possible account.

Pretty much spot on, most of the dobbies I have seen are f4.7/ f5, the EPs are/ will be the X-Cel LX as you say and yep to see more and not worse. Thanks for the advise.

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I have the 250px (solid tube...it's my avatar), upgraded from a 130p which is similar to your current scope.  If you are able-bodied then you will probably be able to lift the tube and mount together. 

You can get some excellent deals on it if you are willing to wait til one comes up 2nd hand - they do so fairly regularly.  I got mine for £155 on ebay - nearly 1/3rd of the new price and it's in very good condition.  Patience is key, but if you're going new then there are usually some discounts around in a month or so on a lot of astro sites so it might be worthwhile holding off for now and doing some more investigation. 

As for EPs, you should obviously be mindful of whether they will work in your upgraded scope.  I've heard before that the LX's aren't great with fast(er) scopes and the BST Starguider range, although a bit cheaper, actually perform better.  Again, there are many better quality EPs around the 2nd hand market, some going for great prices.  2nd hand astro gear tends to be well looked after, but obviously be cautious as you would with any used buys.

Clear skies :-)

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I have an 8" flextube 200P just for home use.   It is easy to take out into the garden, seems to hold collimation (once I had the guts to sort it out) really well and I made a tube cover for mine, but if I being honest I don't notice much difference without it.  Having seen pics of the non-flex tube versions I do not regret my decision to get the flextube.   It folds up and stores in about the same area as a dining chair.  The 10" would just be that bit bigger all round.

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I concur with others above.

Going from a 5" scope to a 10" is a huge upgrade (went from 4.5" to 10" myself) massive improvement and lots of "WOW!!!" moments lie ahead.......

Enjoy :) 

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