8" or 10" Dob

[cookiemonster]

Hi everyone.
I've been reading the forums for a while looking for advice on first scopes. I am planning on joining my local club and going to meetings etc, and doing all the things that have been recommended for beginners. It's all fantastic advice!

What I want is some advice regarding differences in portability (and therefore utility) between the 8" and 10" scopes. Is there a real difference between carrying them outside and setting up?

Thanks

[Waxing_Gibbous]

Hi and welcome to IIS.
Yes. There is a difference.
While a 10" is by no means unmanageable, it is still a good way less manageable than an 8".
I started out with a 12", went to a 10" and wound up with an 8"!!
The beauty of an 8" Newt is (providing its not a collapsible design), you can also mount it fairly easily on a decent Alt/Az mount, making it even easier to use.
If you do decide to opt for the extra 'grunt' of a 10", my advice FWIW, would be to, if possible, find a permenant spot for it to live outside and use a good quality 'scope cover to keep the elements away.
You'll see far more use from it than if you have to drag it out every session.
Good luck and Clear Skies.
Peter

[dannat]

I think they are pretty similar length wise 10" bit heftier, usually the 8" has longer focal length so is kinder to cheap ep,s

[barx1963]

I think the big difference with an 8" and a 12" is the level of commitment. Quite frankly you have to be a committed observer to bother carrying a 12" scope outside. That is why I usually recommend an 8". Having used both I know you can do a lot of observing even with some light pollution with an 8" and it is almost a grab and go unit. The 10" dobs obviously fall between. If you are a fit person used to handling bulky objects (and you are comfortable with the extra $$$) go for the 10", if any doubt, get the 8" and see how much you enjoy using it. If after 3 months you find yourself anxiously waiting for the next clear night, it's time to upgrade!

[ZeroID]

Aperture rules. Go the 10" for the extra light gathering power, 1317 vs 840, a significant gain. An 8" is normally f6 and a 10" f5 so they are the same length more or less physically for only an extra 2" of girth. Ok, a little bit heavier and bulkier but if you're reasonably fit the extra aperture is worth it for visual neb views.

[cookiemonster]

Thanks everyone. I think I will go with the 10".

Another question: I was looking at collimation; and it looks as though you need a laser collimator for it to be a one man job with a 10". Is this correct? If so, I will get one of those too.

[AG Hybrid]

You don't strictly need a laser collimator. But it certainly makes life easier. Collimation becomes an easy one man job, and a 2-3 min job. It will also give good-enough collimation for visual use assuming your secondary mirror is correctly aligned to the focuser already.

[StarTrucker]

Hi, Im going to buy a 10' Dob in the next few weeks. Just how heavy are these things ?? I dont wanna best a gut everytime I want to have a perv !

Ian.

[BrisGreg]

If you buy a 10", I don't think you will be wondering evertime you use the scope if the 8" would have been that much lighter (they are both big scopes) BUT I'm sure everytime you're looking at a faint fuzzie, you'll be wondering how it would look thru a 10":eyepop:

Incidentally, Bunnings have a great flatbed hand trolley for $40 which works a treat for my 10" collapsible

[keni]

Hi Ian,
I can vouch for what BrisGreg said about the flat trolley.
My mate and I use one to move our 10" Dob around and it's great.
It's stable enough to leave the scope on it while we use it.

There's also an excellent article here for moving your Dob. around safely.
http://www.iceinspace.com.au/63-12-0-0-1-0.html


Ken.

[AG Hybrid]

AWWW why didnt i think of that?? That would be perfect for shuffling around my 12".

[Liz]

Yes CM, a 10" Dob is the way. :thumbsup: It can be a bit heavy and bulky, but views are better than the 8", so worth the extra trouble. :)
The laser collimater is good also - I am a bad collimater, but aim to perfect that this year, and collimate each session instead of once a year. :whistle:

[mr bruess]

The bigger the aperture the better.
I'd go for the 10 inch.
Extra light gathering power :D:D:D:D:D:D:D:D:D:D:D

[cookiemonster]

Thanks everyone. Decision made. 10" with a trolley similar to this one. I will let you know how I go! I may well be crashing your meetings some time soon!

[ColHut]

I would recommend that you make sure your trolley has pneumatic tyres. It makes a big difference to the bumps.

regards

[stattonb]

go the 10'' and see if you can get a collapsible so its easier to cart around,but like others suggested get yourself a trolley you will thank yourself for it lol,theres no substitute for aperture 10'' is the way to go.

[cookiemonster]

Thanks everyone for your advice. The scope was for my partner, who is an avid reader of IIS (so i had to be discrete). He loved it! Maybe we will see you at a star party near us soon (Mangrove Mountain)!!

[Liz]

Glad to hear he liked it Anna. :thumbsup:

[AstroGuy]

Depends how strong you are! :)

Of course, truss Dobs are more compact to cart around in the car etc...

[Benboy]

So next question would be is a 12" that much harder to cart around than a 10"? Im looking at upgrading my 6" Dob and I think I might have aperature fever.

[Liz]

Yes. I have a 10" .... not much of a problem, but 12" a lot heavier, unless you have lotsa muscles. 12" are obviously better light gatherers, so if you can handle it, go for it, but they are heavy. :help:

[madbadgalaxyman]

The volume and mass of a physical object is a hard thing to intuitively understand, in relation to its physical dimensions.

If you double the dimensions of of an object, given the same design and the same materials, then its volume and weight go up by a factor of 8. This is why a 6 inch is easy to move around and a 12 inch is always a large heavy object that is hard to lug around.

Assuming a constant design and materials, a 10 inch weighs twice as much as an 8 inch.

Assuming a constant design and materials, a 12 inch weighs 1.7 times as much as a 10 inch. This means 70% heavier!!

A 10 inch is usually the upper limit for some of us who are not strongmen or who have a bad back, at least if we want to move the 'scope around moderately easily. There have been some ultra-light weight 10 inch telescopes around which are very suitable for ladies or for weaklings like me (I am an M.) , but many 10 inch telescopes are quite large and heavy.

Also, a well designed 10 inch is probably what I would call a large "ladies telescope" (I don't mean to be sexist here), unless of course your lady is uncommonly large and strong.

There are a few 10 inchers around that are relatively easy to move around, but some of the heavier ones are massive.

I once had a 10 inch F6 Newtonian which was very difficult for a single person to move, as it had a metal tube, so I ended up cutting it down to F4. The shorter tube was easier to handle and lift; furthermore the F4 tube fitted neatly onto the back seat of a small car.

My advice is to learn what you can see with a smaller telescope, and to learn to handle a smaller telescope with facility, before moving on to something larger.

[[ People these days get giant telescopes before they have even trained their eyes to see Deep Sky objects properly, and before they have learnt how to use telescopes with facility; BAD IDEA, as you end up with a rarely used White Elephant. ]]

A 12 inch is nearly always a "bugger" to move around, whatever the design, though perhaps there are some 12 inch telescopes that are not absolute brutes in size and weight.

Unless you are a dedicated observer of long experience, an 8 inch or a 10 inch will probably get a lot more use than a 12 inch or a 14 inch, due to easier handling and greater ease of use.

If you are enthusiastic about galaxies, a 10 inch is a big step up from an 8 inch in terms of what you can see. However, if you are happy to view planets, star clusters, nebulae, etc., in our own Galaxy, then an 8 inch in a good sky will do the job very well.

cheers,
madbadgalaxyman

[overlord]

Listen guys... I think that ANY dob 6" and above will need to be on a trolley and kept in the garage. (I stuck my 8" f/5 on a lawnmower.) Or it just won't be used that much. These things are heavy. If you live in an apartment don't bother with a dob unless you have a balcony or whatever. Just get a small scope. U will use it more and enjoy it more.