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C9.25 SCT on CG5 or 12" Synscan dob?


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Both are within my price range, the 12" Sky-watcher dob with Synscan is actually cheaper than the C9.25 which I initially settled on, but I just bought the CG5 mount and hate the idea of trading it in already for a dobsonian.

I will use it for backyard observation, no astrophotography, so portability and the imaging difficulties with dobs are no issue.

However, for DSO's and planets, would I rather want the larger aperture dob over the C9.25?

I know there's no such thing as the perfect telescope for everything, but what would you chose if you were me? I love the planets, but I would also be able to get a nice «detailed» view of i.e. M31, which now just look like a dark grey cotton ball in my F/8 6" reflector.

Will a focal reducer give the C9.25 better and brighter views of DSO's?

And I heard that Synscan is not as good as Celestron's GOTO. Any opinions on this?

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I feel the Celestron goto just has the edge over Synscan being marginally more logical and intuitive (to me) - however there's really not much to choose between them - both are very good.

I'd keep the CG-5. You can put a 6" or 8" newt on it later or a decent widefield refractor for a very modest cost, add motors/goto for a bit more.

The SCT will give crystal views of solar system objects with it's long focal length. It's also very capable for dso's. The reducer will shorten the focal length and speed it up for AP. But observing with the reducer gets mixed opinions - some say it's great for observing dso's - others not so positive.

Ultimately it all depends what you want to do. The SCT will be a good all rounder for observing and AP, the dob amazing views of just about everything with the right ep's, and the CG-5 flexible enough to take whatever grabs your interest in middle weight OTA's :o

Edited by brantuk
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I love the CPC and would never part with it (unless for a 9.25 replacement lol). The tracking is absolutely spot on (even when wedged in eq mode) and the optics are superb. I've used a 9.25 at star parties and the extra light gathering makes it better still (though not as significant as an 1100). With planets/moon I can get an almost "3D effect" using binoviewers - it's awesome.

I have last years model of the auto-tracking 300P - upgraded with the addition of a goto handset. It tracks very well for observing, has a little backlash (down to balance), but not accuratey enough for AP - as you'd expect from an alt/az mount. That said, the object stays in the ep for a good 30mins before drifting - so a webcam on planets is perfectly feasible - but forget dso pics. This years goto models have improved encoders/motors so I imagine the tracking is better still.

I couldn't decide between the two so ended up with both lol :o

Edited by brantuk
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Nothing you can put on a CG5 will compete with a 12 inch Dob on deep sky. The Dob has aperture and field of view on its side and nothing is going to change that. If you have a 2 inch widefield EP there is no point in using a reducer on the SCT. It will still leave you feeling a bit 'boxed in' on the wider DSOs. However, the 9.25 views are great in my experience and better than in my 10 inch Meade. On the Solar system the comfort and convenience of the 9.25 might be a significant asset over the Dob.

'No photography' does spell Dob, though.

You want them both, come on!

Olly

Edited by ollypenrice
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What a difficult decision. I have a 10" Dob which when used with my TeleVue EPs give the most fantastic views of DSOs. Therefore the 12" is going to be better.

In saying that at SGL5 I viewed Saturn through Ian's (Astronut) 9.25 SCT with his Pentax EPs and it was the best view of this planet that I ever seen.

Whichever way you go its going to be good.

Mark

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Yeah, I simply cannot decide! Although the C9.25 personally has an edge over the 12", but this is simply due to it's elegant design and smaller footprint, while the dob is big, bulky and almost clumsy looking, in my opinion. Still, it's almost 3" more aperture, aargh...

By the way, the C9.25 has a 1.25" star diagonal. Can it be fitted with 2"? And would a 2" eyepiece be beneficial if used with a 1.25" adaptor thingie?

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It can be fitted with 2" diagonals and ep's - no problem. And yes you can use 1.25" ep's with an adaptor - most 2" diags come with the adaptor. I don't notice any benefits using the 1.25" ep's - the big benefit is the wider fields from a 2"ep :o

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Will it require any modification in order to be fitted with a 2" diagonal?

Anyway brantuk, how tall is the 300p when fully extended and completely vertical? I'm «only» 1.78m, and would I need something to stand on if it's pointing directly upwards?

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Hello Lerxst,

If you want the best planetary views then a 12" scope with it's greater resolution and 23% central obstruction will outperform a 9.25" scope with a 36% central obstruction. Plus the 12" scope will have no mirror flop, no image shift when focusing and will cool down quicker if you put a small fan behind it.

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I'm not dead sure about the Dob winning on the planets though... Optical finesse must not be overlooked. M13 in a big scope - yesss! Fantastic in our 20 inch. But the planets are much better in the apo or the SCT than in our big gun.

Olly

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Olly, we agree planets are better in Apo's but the OP didn't list that as an option.

Out of interest which gives the better planetary performance the TEC 140 or the 10" SCT ??

Sure, but I did say 'the apo or the SCT.' I'm not evangelizing apos - for once!

I prefer the apo on the planets. No doubt about that, but I observe them for pleasure, not to record critical detail. BrianB made the interesting point that the SCT view might be 'scruffier' but hold more detail. I find the apo sharper and more attractive.

However, the 9.25 which interests the OP will surely give great planetary views, though whether better than the Dob I know not. Our f4 Dob is not planetary but, for some reason, sometimes does very well on Jupiter. It's the colour that makes it - real brick reds in the belts.

Olly

Edited by ollypenrice
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FWIW (and slightly OT) I had my ED120 and Skywatcher 7" Mak/Cass out side by side last night on Jupiter under decent conditions and the ED pretty much held its own up until around x200 but beyond that the Mak held the magnification a lot better.

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However, the 9.25 which interests the OP will surely give great planetary views, though whether better than the Dob I know not. Our f4 Dob is not planetary but, for some reason, sometimes does very well on Jupiter. It's the colour that makes it - real brick reds in the belts.

Olly

I also assume that the SCT has a narrower FOV? It seems like I will eventually land on the dob. I'm at 59°N, so taking that in account, planetary details may not even justify a SCT, given the amount of atmosphere that's in the way.

By the way, what would M31 look like through the eyepiece of a 12"? A bright faint fuzzy or will I be able to see more details?

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2 other factors:-

12 inches picks up more atmospheric instability than 9.25 so the latter should give steadier but slightly less detailed views.

The 12inch is wider & £1000 less so that would seal it for me as the one to go for (but then I'm broke so that might not count in your situ !)

Whatever you decide you'll always wonder what you missed in the other choice :o

Alan

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Hello Lerxst,

I am going to throw in a curved ball ......

I have a Skywatcher 200mm F/6 Dobsonian that I bought tube rings for and mounted it on a CG-5. It's a good combination in terms of stability. It is also easy to collimate and gives very sharp views. It's stable when focusing and cools quickly as I added a cooling fan. As it's only 8" it is useable on more nights than a larger scope. This scope is a match for my 5" APO on the planets.

Given your price range you could buy a 8" scope with premium optics, mount it on your CG-5 and have the best of all worlds.

Edited by dweller25
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I was initially dead set on the C9.25 and thought nothing would persuade me to chose different (except if the CG5 would handle a C11 well - which it doesn't), but the more thought I give on the subject, the more the 12" stands out as the sensible choice.

dweller, I have a 6" now so a 8" would unfortunately not feed the aperture hunger that runs in me. :)

I'd love a great and detailed view of the planets, but there are 8 of those and 40.000+ celestial objects (at least in the HC's databases), so in my opinion it would be foolish not to sacrifice some planet detail in favour of magnificent DSO's.

Anyway, has noone else heard about any Sky-watcher GOTO difficulties on the dobsonians? If not, the decision is settled. :o

Edited by Lerxst
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The 300P is 64" tall when extended virtical and the ep/drwtube is at 59". It collapses down to about 46"-47" with a 24" diameter base for storage.

At 1.7m tall I'd say you might find yourself bending knees a little bit to look in the ep :o

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