8" or 10" Dob

[Liz]

Originally Posted by 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.

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.

[madbadgalaxyman (Robert)]

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 (Charles)]

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.