Dobsonians - pros and cons?

[emadmoussa]

Hi there,

Like a lot of you might be are aware I never got a long with reflectors and I had 2 of them - Newtonians to be exact. Optically I thought they were excellent, but found the tube and eyepiece position on an equatorial mount a bit of a pain. Let alone the orientation of the eyepiece  as apposed to the finder scope / Telrad.

From what I see Dobsonian moving mechanism allows the eyepiece to stay on the same side all the time and above all there's no need to rotate the tube or use counterweights. So far this is a big plus for me. I also like the ease of use.

Having said that, perfect telescopes don't exist and I'm sure a dob is not an exception. For a non-dob user, what to expect in the beginning? Pros and cons?

BTW, I'm asking because I'm NOT pulling the trigger on a dob, just want to know in case I want to give it a shot in the future. Unless somebody will let me borrow theirs for a test drive :D

Thanks!!

[Naemeth]

Dobsonian mounts are really easy to use, although the eyepiece can get quite low down, at most elevations it's at a comfortable height and the eyepiece is never in an awkward position! Nudging is also very easy with a dob, and they are pretty easy to balance if you have to .

[emadmoussa]

Dobsonian mounts are really easy to use, although the eyepiece can get quite low down, at most elevations it's at a comfortable height and the eyepiece is never in an awkward position! Nudging is also very easy with a dob, and they are pretty easy to balance if you have to .

How about carrying them around - say a 10" dob ?

[leelee970]

How about carrying them around - say a 10" dob ?

I made a very simple cradle (out of plywood) to place the OTA in while I positioned the mount, and then simply lift the OTA back onto to mount.

 

My Dob is the Meade Lightbridge 10" - it is more cumbersome than heavy but manageable.

[emadmoussa]

So cuddle and walk?

[foundaplanet]

Personally I think a 10" f5 ish dob is the perfect telescope and is a do everything I want it to do. Easy to move about and transport, not difficult to store, sets up in 5 minutes, simple to operate and gives very good views of everything I want to look at. For me this is the all in one telescope and on these points for a laid back approach to astronomy it simply can not be beaten. That is not to say I wouldn't like a 16" or a 20" or and 8" apo but on the practical side of things it does tick all the boxes for me.

[nephilim]

Although I still havnt got mine yet, I'd go for a 12", you've had the 8" newt & the jump to a 10" isnt that spectacular (I'll be shot down for that comment i'm sure ) But my experience with a 12" was WOW!! The difference between an 8 & 12 is a big one so go for a 12 cos you will in the end anyway!!

[nephilim]

In fact knowing you, just go for a 20" mate

[emadmoussa]

As much I'd like to have 6" apo, I'm kind of satisified with my Individual 152/900. I compared it with somebody else's 6" apo, and to my surprise it turns out to be excellent for an achro. But yes, a dob could be a good low maintenance option.

[Schorhr]

Again, it depends on what you consider "walking" and beeing portable ;-)

Even the SumerianOptics 10" 9kg can get pretty heavy after walking a mile :-D

But despite the portability issue, dobsonians are easy to use, it's easy to track objects even at 200 or 300x, despite what some eq mount fans state.

If you ever plan on getting one, don't hessitate, for purely visual observing it's quite nice, and with a camping chair or ironing-chair pretty comfortable, too.

[emadmoussa]

In fact knowing you, just go for a 20" mate

LOL - you don't want to see the look on my wife's face if she sees a 12" dob...a 10" is as small as I make it look to her. Psychological preparation. But a 12" will be like the very very noticeable elephant in the room. Actually an elephant sitting on the couch

[Qualia]

I too echo Foundaplanet's sentiments. A 10" f/5 just seems about perfect. Simple to set up and use, intuitively easy alt/az mount, simple to maintain, etc. Some people don't like the idea that if you're viewing nearer the horizon, you will be quite low down and that near the zenith dobs are tricky to star hop. But then there's no pleasing everyone. To get my own 10" out to a dark site I use a RocknRoller:

[rowan46]

If you are worried about moving it get a sack trolley and a couple of bungees I've moved fridge freezers with those things so a dob would be no problem. I have never owned a dob but I have used them at starparties they are certainly as easy to use as my alt az mounted refractor, The learning curve for how to move them and track with them is a couple of minutes they really are incredibly easy to use

[Schorhr]

That's pretty neat, I got a inexpensive kid trailer for my bike (and it can be used as jogger, too).

[emadmoussa]

Pretty comforting how many dob enthusiasts out there..

[foundaplanet]

Pretty comforting how many dob enthusiasts out there..

After the actual optics the Dob mount is probably the greatest invention in the history of the hobby.

[Wyvern]

Hi,

I'm a big fan of dobs. Some many years ago I bought a 10" f4.2 mirror and flat to construct my own beast. (By buying, I figured any final problems wouldn't be down to a mis figured optics at least!)  It's been through several metamorphosis over the years, but has always been quick and easy to transport around and to set up and start observing, - the key to a big portable scope me thinks!

You very quickly get use to moving the scope in straight up/ down, or left/right motions. Star hopping to targets is a breeze.  Only drawback is if photography is required. You'll then need some type of equatorial platform to sit the dob cradle on to get around an hours worth of "equatorial action".......  in which case you'd buy/make an equatorial mount for it in the first instance. 

Shortly after my first build, I was at field meeting with my then local astro society in the south of England. Was happy bunny picking off targets when in rolls a member who'd vanished for several months. Attached to the back of his 4x4 was a 8'x8' trailer with a monster of a 20" scope. Some 40 minutes later after getting the thing ready to use, he utters the immortal works...... " right...... what can we see?"       Think it was a testosterone thing...  mine's bigger than yours....... but at least I know what to do with my 10"

Regards

Les

[stevetynant]

Based on my experience of an 8 Inch Dob which is obviously going to be different if you go huge but

Pros

Easy and quick set up

Easy storeage

The ability to mod very simply and inexpensively

Sit down to view or place on platform - take your pick - viewing position easily adjusted

Great for deep sky and planets

relatively cheap in comparison to Eqs

Can add an equatorial platform for tracking but not really necessary

Cons

No A/P

As far as I've seen to date thats it on the negative side

Like I said its a purely personal thing but really enjoying mine- may go 12 or 16 Inch in the future but sticking with Dob.

[emadmoussa]

One question though..

Which is better, the Sky-watcher Skyline 250mm or the Revelation (GSO)?

I noticed the Revelation has a better base, dual focuser and a cooling fan.

[oldfruit]

One question though..

Which is better, the Sky-watcher Skyline 250mm or the Revelation (GSO)?

I noticed the Revelation has a better base, dual focuser and a cooling fan.

From my own experience the Revelation has smoother actions in alt/az than the skywatcher but that is only in my own experience. Visually there is nothing in it.

[foundaplanet]

One question though..

Which is better, the Sky-watcher Skyline 250mm or the Revelation (GSO)?

I noticed the Revelation has a better base, dual focuser and a cooling fan.

From my experiences of the two makes I don't think there is owt much in it though I would say in my experience the motions on the Rev are better, that may just be the way they have been set up.

[foundaplanet]

From my own experience the Revelation has smoother actions in alt/az than the skywatcher but that is only in my own experience. Visually there is nothing in it.

[emadmoussa]

Wow!! Are you two twins?

[Naemeth]

How about carrying them around - say a 10" dob ?

Easy. Skywatcher 10" OTA weighs around 13kg, base weighs 15kg. Carrying them both together is do-able, it's just it's rather an awkward arrangement so I have to waddle when I do pick both up - the weight of the set-up isn't the problem.

I've even taken out the 10" dob after a long 10 hour shift at work, no problems.

[mitchelln]

I have the 12" SkyWatcher FlexTube and it really is the limit on what is luggable. The tube weighs 20 odd kilos and the same for the base. The base of the bigger ones won't fit through a door without dis-assembly. At a recent gathering a chap came with a 14". It needed two people to get it out of the car and carry. He put it up for sale the next day!

As is often said here, the best scope is the one you use

One thing with dobos is they are not suited for deep sky photography. The tracking isn't up to it. Great for planetary though.