Thinking about a Dob...

[Rick Parrott]

Been giving some serious thought to purchasing a Dob 'scope. I already have a 6" Reflector on equitorial mount and it is great, but it doesn't easily pull-down for car transport so only really gets used at home. I'm thinking the Dob will be easier to transport, whilst going for a larger diameter.
My question - while I understand it's basics - how do you use these? :shrug: Do you need to kneel down next to the thing? What are your experiences?

[Stu Ward]

The smaller dobs (8 ") are 1200mm Focal Length so the tube is around 1.3m long in total.
The base pivots at around ( guessing ) half its length. Therefore depending on where the object is situated in the sky determines at what height the eyepiece is.
If the object is near the horizon, then the average male would be on his knees to observere. At the Zenith then you are standing up with slightly bent knees.
Most comfortable observing is done sitting on either an adjustable astronomy chair or the famous Aldi Ironing chair.

Hope this goes some way to helping.

Stu

[Suzy]

That was so incredibly well explained Stu! :thumbsup:

[erick]

Good thinking Rick!

Unless under your feet is mud and mush (!), try an old gas lift office chair. A draftsman's one will give a greater range of adjustment. Rip the back and arms off. Leave the wheels on if you are on a hard surface and you'll be able to move around hardly having to touch the ground.

Yes, you do get a wet backside from the dew, but what's a little bit of suffering for your hobby.

Also if you insist on trying to observe objects below about 15-20 deg elevation (and we are all that stupid from time to time), you should get a small child's stool and swap out the chair for that.

[Osirisra]

The flexible/collapasble dobs of around the 10" mark would be fairly easy to transport in the back or a standard car. My 14" is a just a bit big for day to day travel but the base does pull apart and all it crams into the back of my Jeep. Bit of a mission pulling it up and down but with a smaller size it would'nt be a problem at all.

[Liz]

Go for it Rick!!!
Dobs are sooooo quick and easy to set up, with viewing able soon after.
I can set up my 10" in about ... 4 minutes easy.
I also use a gaslift stool for easy viewing.
Q is .. do you get an 8 or a 10"????

[Stu Ward]

or a 12,14,16 ......

Once aperture fever hits !!

[mental4astro]

Hi there,

While I'm all in favour of dobs (I've got 4 and counting), bigger isn't always best.

Stu has explained how simple they are to operate. Nicely done.

While your equatorial mount can be tricky and time consuming, a 10" dob is a big sucker if it is a solid tube. Unless you have an appropriate car to take something that big, you can be in for more bother than you would like.

Before laying your money, I'd suggest you get to a star party organised either through an astro club, or any listed in the Star Parties forum. There you will see dobs of all sizes and configurations. Solid tubes and truss type. And how easy they are to use. If you ask really, really nicely, some fellows will allow you to have a fang of theirs. Oh, and take a scope of yours along too. You'll gain twice as much that way from the visit.

Now, don't forget another thing. If you are handy with tools, you may like to get your hands on a solid tube dobbie, 10" or 12", take to it with a hammer (so to speak) and refashion it into a truss one. Have a look at what I did to the 17.5" I reworked... before & after. And my 10" dob too.

[ballaratdragons]

You say you already have a 6" f5 reflector. Why buy another of the same thing?

You have the scope. All you need is the Dobsonian base.

Lots of folks have made Dob bases for their scopes. Gives you 2 options to use the same OTA: EQ or Dob.

I have seen some really nice Dob bases with an opening box where you place the OTA in and lock the box. Takes all of 5 seconds. :thumbsup:

or side bearings mounted to some tube rings.

Create, enjoy :)

[mental4astro]

:rolleyes: of course!

These cost less than $50 each to make, with change left over for a coldie or two to baptise with.

[Rick Parrott]

Wow, thanks everybody for some great tips! I like the idea of making a dob mount for my existing; whilst I have zip handiwork skills my brother is very clever with all things metal and wood! ;)

Home has a nice "Greek" backyard consisiting of lots of nice smooth concrete, so their is ample room for using any setup!

I still might have a look at a bigger 'scope; we have a big wagon and no issue with space, and we often go camping (though we usually attract lots of cloud accompanied by rain :lol:).

[ZeroID]

Go 10", it's the only way to get serious. Big difference in seeing over a 6" for sure. My homemade packs down in about 2 minutes and is operational again on site in about 10. I just remove 4 alum struts and lift it off the base, chuck it in the back of the wagon and away we go. Aperture rules !!
I'm 1.75 m tall and viewing at zenith is just below my normal eyeline, I use a chair and most viewing is above the 30 degree mark anyway.