Dobsonian size comparison

[John]

I've posted this before from time to time but not for a while. The illustration below is adapted from something the US company Orion use to show the comparative sizes of dobsonian scopes. There is a little variation from brand to brand but it's broadly accurate I feel.

In terms of overall weight it goes something like:

6" dobsonian = ~34 lbs / 15.5 kg

8" dobsonian = ~40 lbs / 18 kg

10" dobsonian = ~55 lbs / 25kg

12" dobsonian = ~ 83 lbs / 37kg

Might be of interest to those considering upgrades or first scopes

They always look bigger than you expected when unpacked and assembled in your living room. And much bigger than your partner expected

[LukeSkywatcher]

I dont think the weight comparison of Dobs is fair. Its really more about the size and storage of them.

[John]

I dont think the weight comparison of Dobs is fair. Its really more about the size and storage of them.

I only provided it as a bit of further information Paul. I'm not trying to evaluate them on the basis of it

[LukeSkywatcher]

I only provided it as a bit of further information Paul. I'm not trying to evaluate them on the basis of it

I know, but with Dobs............it really boils down to size and storage rather then weight.

[markswift]

I still get shocked when I see a large Dob setup, wouldn't exactly fit my grab and go needs, but excellent scopes all the same!

Great post.

[Black Knight]

They always look bigger than you expected when unpacked and assembled in your living room. And much bigger than your partner expected

I think we should call that John's First Law of dobsonians:

They always look bigger than you expected when unpacked and assembled in your living room. And much bigger than your partner expected

[LukeSkywatcher]

When my Celestron 8se arrived just over a year ago................it came in 3 boxes and i thought i was unboxing a mini cooper car or a pony.

[BargeGazer]

Paul, Surely weight matters to a lot of people. If thy cannot carry it and assemble it safely then they would be wrong to buy one. And a lot of people have to do it on their own. So weight is a factor. Not the only one but it is a very useful factor.

Thanks for the info John. I am considering a 250/10" and that will be enough to handle. The thought of hefting 37 kg about is enough to say NO to a 12". I am 6ft 4" so height is less of an issue - and I have a Landrover (the boxy type) to shift stuff about in.

David

[UHF]

Its probably best to agree that everyones requirements are different. some will want aperture over everything. Some will want a balance. some will find the ep height important for comfy viewing. flex vs solid. best thing to do is present the info so people can decide due themselves which is what has been done.

Sent from my GT-I9100 using Tapatalk 2

[brantuk]

Very useful comparison John - specially for someone who's considering buying a dob.

It allways amuses me when girls are surprised that something turns out bigger than they expected hahaha

[Bart]

A couple of things, weight is very important if you are going to be lifting them in and out, and secondly, John, you're supposed to have been practicing your 'surprised by the size of it' look well before the beasts arrival.

Barry

[Coopz]

Very useful info, thanks for posting. Does anyone know the base diameter measurements for each scope as an 8" (I think it's base is 52cm but may well be wrong) is on my list of potential first scopes and for me personally it's more about the size of the footprint it takes for storage rather than height or weight.

Many thanks

[umadog]

It's true they look bigger than you expect and bigger than the stats and the info graphic suggest. But it's also true that you adapt to the size: it doesn't seem so big after the first couple of weeks of ownership. If you think your 8" Dob is huge then just go to a star party and set it up next to a 12". You will never think your 8" is big again. Ditto with a 12" if you set it up next to a 16". Ultimately, what dictates the maximum size of your scope becomes price, door width, car size, marital situation, storage options, and set-up motivation.

[Luke]

Paul, Surely weight matters to a lot of people. If thy cannot carry it and assemble it safely then they would be wrong to buy one. And a lot of people have to do it on their own. So weight is a factor. Not the only one but it is a very useful factor.

Thanks for the info John. I am considering a 250/10" and that will be enough to handle. The thought of hefting 37 kg about is enough to say NO to a 12". I am 6ft 4" so height is less of an issue - and I have a Landrover (the boxy type) to shift stuff about in.

David

With the 12 inch flextube, I think the base weight is 18.5kg and the tube weight is 21kg. You can carry the tube and base out separately (they come apart in seconds, it's one big screw if I remember correctly), so max weight in one go would be about 21kg for the tube.

I found it no huge deal to move but then again I thought my first scope, a 76mm reflector, was massive. It's strange what aperture fever can do to you!

[RikM]

Very useful info, thanks for posting. Does anyone know the base diameter measurements for each scope as an 8" (I think it's base is 52cm but may well be wrong) is on my list of potential first scopes and for me personally it's more about the size of the footprint it takes for storage rather than height or weight.

Many thanks

I just measured my 250PX and the base circle is 52cm diameter (57cm across the handles) the base is 73.5cm tall. OTA is 114cm long and 28.8cm across the tube and 34cm across the bearings. Floor to dust cap pointed straight up (in storage position) is whole thing is 135cm tall.

[swamp thing]

Very handy little chart John.

Gives a great overall idea of the rough sizes of them, for anyone contemplating buying one.

I reckon scopes seem to shrink with time. When they first arrive all shiny and new they seem enormous. Give it a few months and its like they've got smaller. This is the point aperture fever starts.

[JD75]

As a newbie, have to say I'm definitely surprised by the size of the scopes, particularly these. It's really useful to see something like this as short of seeing them in the flesh, it's a bit hard to picture them really.

[Scott]

It allways amuses me when girls are surprised that something turns out bigger than they expected hahaha

I wouldn't know brantuk, never happened to me

Scott

[Luke]

Very useful info, thanks for posting. Does anyone know the base diameter measurements for each scope as an 8" (I think it's base is 52cm but may well be wrong) is on my list of potential first scopes and for me personally it's more about the size of the footprint it takes for storage rather than height or weight.

Many thanks

For a 12 inch flextube:

Tube length: 144cm (extended), 92.5cm (retracted)

Base diameter: 64cm

The base can be a bit tight through doors, though sometimes you can angle it and squeeze it through (I didn't believe the missus when she said the base would get through our caravan door, but it did, when angled!)

[umadog]

In practice, bulk is as much of a problem as weight. A 40 lbs sack of grain is a lot easier to handle than a large 40 lbs OTA. Also, once you get to these larger scopes, it's the weight of the heaviest component that's important rather than the weight of the whole thing. The reason Obsession made the impact they did is because they figured out how to make large, heavy, scopes manageable. It's quite feasible for a guy of retirement age to handle a 20" Obsession by themselves. The thing is wheeled about like a barrow: you never lift the whole weight so it's not really a consideration in day to day usage. The weight only matters if you're carrying out maintenance and need to remove the mirror box (a pulley from a beam may be called for if you have a bad back). In practice, it's the bulk that matters. A 20" Obsession won't fit through a lot of regular doorways. Even the base of an Orion XX12 won't fit through narrow doorways.

[Optical Dob]

Probably one of the most useful charts that can be posted on here. Its also a good idea if you can get along to a shop and see how big theses things are. The diameter of the bases are the real surprise. Do they have to be so wide. I suspect the answer is yes otherwise they would fall over.

[RikM]

The OOUK Dob bases have a smaller footprint than the SW or Orion USA circular ones. They are very nice indeed but do cost a fair bit more though.

[bingevader]

When my Celestron 8se arrived just over a year ago................it came in 3 boxes and i thought i was unboxing a mini cooper car or a pony.

A bit concerned by the "unboxing a pony" comment!

In 3 boxes!

How were you planning on putting the poor creature back together?

Some mad scientist Frankenstein experiment or a years worth of horse burgers?

Cheers

[mert]

I had a 12" Skywatcher flextube, tube was really easy to move around, when I moved the base around I did whack my ankles of it a few times, l also removed the eyepiece holder at the front, it was deadly

[Lenny147]

I think weight is a big factor, i have the 10 and its fairly heavy in one piece. Still worth the effort though