GSO 6 or 8 inch??? any advice

[Dan31415]

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I have been cruising the forum now for a while and finally feel comfortable to post a question... I am considering a first scope and have decided on either a 6 or 8 inch dob from Andrews. From the posts that I have read I know that size counts (also from viewing with a pair of 20x60 binos). I expect to purchase a larger scope later in the year, perhaps a 16 inch GSO/Meade if they ever come out. What I would like to purchase now is a smaller 'grab and go' that is good enough to keep for the long term. I would expect to flock the scope as well as well as replace the spider with a curved spider from protostar or something similar.<o:p></o:p>
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So far the advantages of the 6 inch is the longer f ratio (good for planets and lunar) and smaller size, but the disadvantage is the 1.25’ R&P focuser. Whilst the main advantage of the 8 is the larger aperture and the 2 inch Crayford focuser (on the $449 model), the only downsize I can think of is the additional size and the extra $150. Having said that, size isn’t really that important. I have had a look through a 8, 10 and 12 inch dob and liked the view each provided, but have not looked through a 6 inch. (I must admit I didn’t see a large difference between the 8 and 10 or the 10 and 12 – but I put this down to inexperience). The skies where I observe are almost completely black, with the milky way absolutely breath taking to the naked eye and M42 always a nice shade of green with the binos. <o:p></o:p>
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I would also like to make a f5 dob over the next 9 months and would expect that I would make either do a 6 or 8 inch depending on the choice I make now. Any advice that you could offer would be greatly appreciated. <o:p></o:p>

[matt]

Short answer. Go the 8". Especially under your dark skies.

You'll really notice the extra aperture when you go hunting for Deep Sky Objects (DSOs) like nebulae, galaxies and star clusters. More aperture = brighter and better resolved faint fuzzies.

More aperture will also reveal brighter more detailed planetary images.

The more light you collect, the more you can resolve and magnify.

An 8" f5 is very transportable and as you've said comes with a 2" focuser with 1.25" adaptor so you can use both size eyepieces.

But listen to what others say coz you'll get plenty of good advice here. Ask lots of questions. Oh... and :welcome:

[ving]

I cant speak of the 6" as i have never used one... I do however own the 8" and can sing its praise on high!

a more wonderful scope (for the price) you will not find. :) 8" under your dark skies gives you a galaxy hunter!

of course if a 12" you can afford then a 12" you should get if transportation is not a problem. aperture rules the day! :)

if you are considering astrophotographt in the near future then dont get a dob at all, as you will need an equatorially mounted telescope :)

hope i have helped. and welcome aboard.

[norm]

I would concur with the 8" as well. Don't get me wrong, I don't even have a telescope !

However one thing that always impressed me was the time I went to my local Astronomy club for an open night. Of all the scopes that were out there the President of the Society had an 8 inch Dob and it was great, simple in design, portable for its size but with good aperture. We looked at the moon and it was more impressive than some of the lot larger, more expensive scopes around.
It was also the scope that we talked the most about for the night. It certainly took me by surprise given the company it was with. :)

[janoskiss]

This one is a no brainer. Get the 8". You will see lots more with it. The 8" is basically the same size as the 6". Only the tube is skinnier on the 6, but it is just as long. And the Dob bases are the same size too. The 6" is a nice scope, and if you only had $300 to spend it would be a great buy, but if you have enough for the 8" go for it. You might want to also consider the 8" SkyWatcher Dob from Myastroshop for $440. The tubes of the SWs have a much better finish and won't rust, which the GS tend to do. Plenty grab and go enough; for the GS, attaching a couple of handles to the sidewalls of the base helps a lot in this regard (I believe the SW might already have holes cut into the rocker box for handles).

[ving]

I wish people would stop calling GS scopes rust bucket. mine is almost 2 yers old now and doesnt have even a single spot of rust....
:(
I havent treated it or anything either...

[asimov]

Hi Ving...Saw my first GSO 8" dob in the flesh 2 nights ago...no rust on that one either.

[janoskiss]

My 8" has surface rust, Ving. And the paint came off with the double sided sticky foam when I moved my Telrad. It revealed shiny steel under a thin single layer coat of paint. Daniel's Saxon (aka SkyWatcher) Dob has a tough white enamel finish I would not mind on my car. The GS finish is pathetic by comparison. As to which if either has the better optics, the jury is still out.

[ACE]

8 inch without a doubt.



Thats a bold statement to make to say SW's won't rust. Maybe it should be re-phrased to say they may resist rusting better. :D

[matt]

It may be bold ACE, but it may also be true.

I have a SW 8" (the blue tube) and it's clean as a whistle and I don't think you'll find a single post on this website about SWs and rust problems.

So, it's maybe a fairly safe comment too?

As far as the GS tubes go. There does appear to be some folk who just got dealt a bad hand or something as far as that goes. I feel for 'em.

[davidpretorius]

8" and if you can afford to lift and the $$ a 10" or 12"

[Dan31415]

Thanks for the quick reply everyone :eyepop:

The SW680 looks like a great scope and finished off very nicely, but it has a R&P type focuser, is the crayford a great improvement? or on the balance of things not that big a deal?

Thanks again

[matt]

Replace the focuser. Buy yourself the best Crayford you can afford. Pure and simple. Will change your life!:lol:

But seriously it's a worthwhile, easy and affordable modification.

If you buy the scope from MyAstroShop, Steve will also sell you a $140 (???) crayford and maybe even fit it for you???????????

[janoskiss]

Dan, if you are already buying a scope from them, get them to at least match Bintel's & Andrews' price on the Crayford focuser. $99.

[norm]

hmmm - according to their website, they've got them advertised for $149.
Have they gone up from $99.:shrug:

Also 've noticed they've got 10mW green laser pointers for $129 - seems reasonably priced?

[barees63]

Or for only $95 get yourself an Orion Accufocus to motorise your R&P, IMHO this is even better than a crayford since you don't have to touch the scope while focusing so you get very fine focus with no annoying vibration.. also, in winter you can keep your hands in your pockets while focusing :D

[Starkler]

If you live in skies that are good enough that you wont be transporting your scope, get the 12 ;) (or the biggest that you can afford).

[ThunderChild]

While I concur with what everyone is saying (basically get the biggest thing you can afford) - I do have an extra bit to add - since I own the GS 6" model.

I have found it personally to be a pleasure to use. Took it along to Snake Valley last weekend, and the few people that looked through it said it was pretty good too. Obviously not as good as 8 ... or 10 ... or 12 .... or ....

If you ask in this forum to help you choose between any two sizes, you will always get back the advice to go with the larger. And this makes sense if you have that extra money burning a hole in your pocket.
The extra cost of the 8" was too big a jump for me at that time, so I got the 6" and don't regret it either.

Which ever way you go, I doubt you will be cursing the decision down the track - especially if you plan a great big mother of an upgrade pretty soon down the track.

Good luck and let us know how you go!

[wavelandscott]

Hi,

I'll be a bit contrary...while I am a big reflector fan, I would suggest that if you are going to get a big Dob later on that you consider a different type of scope for your grab and go scope...

Don't misunderstand me, aperture does rule and you should get the biggest scope that you will use however, if your plan is to jump up to 16 inches soon, then I'd encourage you to look at a refractor or another configuration...

Some of the other scopes will be smaller than the 6 or 8 inch you are considering and if you are going to have a big 16 inch soon then why not try a different flavor scope?

If you are just going to have one scope that is all around, it is hard to beat the 8 inch reflector...but if it is two scopes that you seek, then I'd give a look at some of the other types...

Just my thoughts...

[Rastis]

Don't be scared.
Go straight to a 300mm refractor.
:) More power, more fun!

[norm]

Holy Toledo !!!!! A refractor too !!!!:scared: :P :rolleyes:

[matt]

a 300mm refractor:scared:

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$

[mickoking]

G,day Dan and welcome to the forum,

I would recommend either a 150mm or 200mm GSO Dob :thumbsup: but a 200mm will show more and is not much larger than the smaller Dob. I currently own 2 GSO Dobs and neither show a speck of rust, and their optics are very good.

[danielsun]

Welcome Dan! Cool name!!
Well i think that if your going to go with a dob i'd personaly get a saxon or sky watcher for a few of reasons.1. I have compared mine with the GS dob and i can say from what i've seen that the paint job is definately better.It seems the gs dobs or at least the one i've seen doesnt have any undercoat which is not too good. 2.The saxons have It a tensioner handle which alows you simply tension at at any tension to hold light or heavy eye peices without the need for counter weight magnets which can scratch your paintwork. 3. with the tensioner handles you can simply pick up the scope and base as one unit and carry it around. (I have the ten inch and still find this easy!) .4. I prefer the polyurathane roller for the altidude bearing set up even though its great as it is , you can still modify it if you like and put proper cased bearings as i have for even more super smooth travel. having said this the saxons and sky watchers are a bit more expensive but i think worth it. The GS dobs are a good budget scope and the GS deluxe has the advantage of a crayford focuser which are excellent.although you could fit one to a saxon or sky watcher later if needed.
Which ever way you go get minimum 8" or if you can afford it go the 10" Hope this helps .

[janoskiss]

After having seen and used Daniel's scope I have to say I agree that the altitude motion of the SW Dobs is superior to that of the GS, as is the continuously adjustable tensioning handle to the springs used on the GS. The only thing that remains to be seen is how the optics compare (but based on what I saw through the Saxon it looked good as does my GS).

[Dan31415]

Once again, thanks for the reply..

I had not considered the skywatcher before it was mentioned here and is now looking like a great alternative - even from the pictures it seems a much better finish. I would like to make my purchase and have the scope delivered before the 20th of March as I am driving from Darwin to Kununurra and back again over a week and would expect the sky to be particularly dark in that part of the world - in the middle of 'no-where'. I will keep you posted of my final decision and perhaps even a first light report:D

Dan

[Starkler]

Just one more thing....

On the GS scopes the collimation screws can be adjusted with fingers, whilst the 8" Saxon dob i owned a few years required a philips head screwdriver for the collimation screws and an allen key for the lock screws.

Its worth checking on if you want to keep your scope well collimated. If its hard to do , you may not do it as often :whistle:

[Miaplacidus]

Someone really should do a feature comparo between the main dobs. My F4 is a GS, my F6 is a SW. No idea if these are standard, but from this limited sample I would say that the GS has superior focuser (came with compression ring), secondary holder, and collimation screws. It's tube is well blackened. My Skywatcher has a better tube, I cannot imagine it rusting (can't say the same for the GS), but the interior is perhaps less black. The recessed allen key collimation screws on the SW are a pain, so I changed them for phillips head screws, which are much better (cost <$3).

Both are good scopes BTW, excellent value, and when all's said and done, you are unlikely to be disappointed with either. But try and check them out in the flesh yourself if you have the chance.

[BC]

Hi there,

If grab'n'go is the thought, I wouldn't be going the "aperture rules" path quite so quickly. Achieving thermal equilibrium is near impossible in winter near Canberra. Even with the fan going for hours the little amoebas never leave the off-focus view. I have the 10" and the views are good but it never gets to that non-shimmery view of the moon (for example). I don't know how much thermal balance you need to achieve up there (warming rather than cooling), but maybe the refractor is worth a closer look, or the 6" reflector for a quicker clear view. I harp on it a bit because it's one of the things I wished I was warned about before going the path of "aperture is all that matters". Besides, you'll get plenty of non grab'n'go with the 16" later.

Cheers

[janoskiss]

BC, A well baffled 4+ watt fan should get the 10" to thermal equilibrium in no time.

The "amoebas" are in your eyeball not in the scope, if they are what I think they are.

The shimmering Moon is caused by the constant motion of the atmosphere and not your scope. Thermal currents within the tube tend to give intermittent blurring and "swimming" ghost images. It is a very different look from the shimmer caused by the atmosphere.

Sure, in a small refractor you will not see it so easily, but that is because that scope cannot handle the high magnifications needed to see it. The atmosphere is never still. If you push the magnification high enough you will always see a shimmering Moon.

[Dan31415]

Thanks Miaplacidus,

I think I have made up my mind, it is just getting down to shipping rates now. myastroshop is only charging $45 to Darwin which is very reasonable:thumbsup: haven't called Andrews yet.

[Miaplacidus]

Oh, another thing. While the compression handles on the Skywatcher are good, and really do work to stop altitude sag, I can't imagine how I'm going to attach encoders to it for a digital telescope computer. (Anyone else out there done this?)

Cheers,

Brian.

[janoskiss]

Daniel has done it. He's got an ArgoNavis on his Dob. :)

[Dan31415]

Once again thanks all for the great advice...

I have ordered a Skywatcher 8 inch from myastroshop in Sydney which should be delivered early next week. :D Steve was a consummate professional to deal with, answering a number of email questions I had within a couple of hours and was extremely helpful and forthcoming with information and an absolute a pleasure to deal with. At $465 delivered it was also a FANTASTIC price. :thumbsup:

On the down side we have a monsoonal trough which has just arrived in Darwin, now all it has to do is turn into a cyclone to be the most extreme example of the new scope curse ever.:doh:

Thanks again for all your advice

Daniel

[janoskiss]

Good stuff, Dan! You'll love the little beast. :thumbsup:

[cjmarsh81]

Congrats on the new scope. It will be awesome. I have ordered a couple things from Steve at Myastroshop and they have both turned up the next day. Could be a day or two more to Darwin though.

Before you flock the scope and change the spider I suggest you use it for a while. I am very happy with my Skywatcher the way it came. Other than re-greasing the focuser and putting extra sliders in the base to make it smoother there is not much you need to do to it. If you are in a dark area, there is probably not much need to flock it anyway(I could be wrong).

Have Fun!

[Miaplacidus]

Congratulations, Daniel. That sounds like a sweet deal. (When I bought my dob they were much dearer than that.) 8 inches are much better than 6.;)

What eyepieces come with it?

[dhumpie]

Good stuff. Hope you get clear skies ;)

Darren

[danielsun]

Well done Daniel!! You will no doubt be happy with it, and very easy to carry around! ;) I've also still got my 8" incher!!

[Adrian-H]

gso's are own i got a 12", sure they are big, but i say it is worth the investment if you are willing to use it!

who said they wanted to buy me a 300mm refractor?

[Dan31415]

10 and 25mm plossl I think