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Minimum sized dob for faint DSO's in relatively good detail?


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Most of my clear nights have been spent on astrophotography in recent months! But I would like a great dob after seeing some at my last star party for when my imaging is on auto. But at what size does real 'detail' start to come through. I know im not going to see it as my camera see's it as our eyes cant possibly see objects in that detail, but what aperture is going to allow me to hunt all the messier objects & other faint DSO's and possibly sketch detail. It would need to be semi portable I guess as Im in light polluted skies but just 30 mins drive gets me into great skies. I have seen a 12 inch second hand dob which sounds fantastic what views can I expect with the dark adapted human eye? All my observing has pretty much been through a camera once I have found it so I would like to go 'old school' for a while :D

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an 8inch will resolve stars in globs and sprial detail in m31 and m51 the dark dust lane will also be visible in 82, but a 12 will make seeing tiny fuzzy a breeze. im after a new dob myself either a 12 , 14, or 16 a 12 would be my minimum now after having a 16. at a dark sight you wouldnt be board :cool:

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I reckon 10" is where it begins to get interesting with deep sky objects having owned scopes from 4" to 12" in aperture. Under dark skies (which are also a huge benefit for DSO's) a 10" scope will start to show some DSO's very well indeed. Of course more aperture is better still but 10" marks a sort of watershed for me.

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Have a flick through some of these most of those sketches from a 12" Skywatcher from good skies.

Personally I think 12" dob is probably the most versatile size going. Enough light grasp for details in DSO's but also short enough to be able to put on a EQ platform for great lunar and planet views.

:)

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i would say first and formost is its about the skys. iv seen more detail and objects in my pair of binoclours than a scope in dark compared to LP skys. a 8" in real dark skys will out preform a 12" in LP (just) so guage it from that scale......... i remember seeing a members post once where they had perfect dark skys (in iraq or near by) more in a 130p than a member with a 12" with lp.

obviously " size is king. more u have more you see (or more detail you will see of current objects)

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i remember seeing a members post once where they had perfect dark skys (in iraq or near by) more in a 130p than a member with a 12" with lp.

I've been using Stephen O'Mearas The Messier Objects as a reference book while going through the list. What he describes and his sketches are very similar to what I have seen except I was using a 12" in the UK and he used a 4" on Hawaii!!!

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Definitely about skies , even to. The point of putting up the magnification to blast out the effects of poorl skies. In average use I'd say an 8", but in pristine skies a 4 inch refractor will blow you away. Some targets practically defy averted vision and imagination.

Really depends what you'd like to see, some of the planetary nebulae are small, but quite bright. A lot of the galaxies will reward you with dust lanes and structure at bigger aperture.

Dream time ( for me ) gives 14 " as being manageable and rewarding,

Nick.

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With a 12 inch dob at star parties, I've seen spiral arms in M51, M31 so bright it took my breath away (and dust lanes clearly visible), and with an OIII filter, plenty of detail in the Veil nebula (not quite enough to see individual branches in the broom, but knocking on the door). The detail I saw on Jupter one morning (I assume the aperture helped) staggered me, it was like looking at a sharp photo when it drifted into focus.

All that said, I think a 10 inch solid tube dob has a lot going for it as well. Enough aperture to have plenty to look at, and light enough to feel almost no effort to move.

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Spiral structure here: http://www.deepskywatch.com/deepsky-sketches.html in M33 and M51 If the skies are dark enough there's no reason an 8" couldn't resolve spiral structure in M33, since it's really a pretty big object. Olly, I reckon it does make a difference if you know what you're looking for so that may be one reason that Rosse was the first to see spiral structure in M51. Also, remember that those mirrors had terrible reflectance properties, so a modern 8" would be equivalent to a substantially larger telescope back then.

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Tough question to answer, as what satisfies one observer may not satisfy another.

Some observers use scopes around 8" aperture their entire lives and are very happy, others go off the other end of the scale with enormous beasts, and still want more light.

Personally I think a 10" is the perfect size. Not too big, not too small, but hey ho! That's me, you could well be different.

Best to have a look through some at a star party or society meet. That will give you the best clue as to where you wanna be Dob wise.

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i feel somebody coming down with "aperture fever"

I've had aperture envy since a week after it arrived. Looked like a dustbin when I first saw it, now it resembles a drinking straw.

The way I see it, this is a good way to keep my interest up. I'll observe everything I can whilst slumming it with my meagre 6", then upgrade in a year or so and observe it all again to see the difference.

That's the thing with this hobby, the potential to upgrade your kit is virtually limitless; but sadly my bank balance is not.

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It would more come down to the sky conditions I think really. I may be wrong, but I believe a 130mm scope under truly dark skies would probably out perform a 200mm scope used under badly polluted skies.

At the dark skies of the SGL star party a couple of years back my 6" scope was showing deep sky objects about as well as my 10" does from my back garden.

I had a look though a 20" at M13 and M51 at that event - now that really does give you aperture fever !

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I've had aperture envy since a week after it arrived. Looked like a dustbin when I first saw it, now it resembles a drinking straw.

The way I see it, this is a good way to keep my interest up. I'll observe everything I can whilst slumming it with my meagre 6", then upgrade in a year or so and observe it all again to see the difference.

That's the thing with this hobby, the potential to upgrade your kit is virtually limitless; but sadly my bank balance is not.

slumming it with my meagre 6", love it :laugh: i can remember my 1st scope a VERY meagre 2" tasco refractor and then the massive 4" reflector :grin: seriously though i know what you mean i did exactly the same upgrading through the apertures to an orion 10" but then back to an 8" and started imaging and its the best move i have made.

come on, come to the dark side of astronomy :evil:

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slumming it with my meagre 6", love it :laugh: i can remember my 1st scope a VERY meagre 2" tasco refractor and then the massive 4" reflector :grin: seriously though i know what you mean i did exactly the same upgrading through the apertures to an orion 10" but then back to an 8" and started imaging and its the best move i have made.

come on, come to the dark side of astronomy :evil:

I'd love to, but I know what I'm like.

A passable image or two would set me off on the path of relentless self improvement and the inevitable selling of a kidney to fund that next essential piece of kit.

For the sake of my sanity I'm happy to just observe... for now.

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