Eq Dob Mount

[gel]

apart from Bintel in sydney who has the johanson mount @ $1150,who else if any sells eq mounts in oz,dammed if i can google it,i keep ending up overseas,any help from a dob owner appriciated-regards

[iceman (Mike)]

I ended up buying an EQ platform from Round Table Platforms in the US. The cost of the platform is reasonable, the cost of postage is not.

If you can find a local supplier, great, but netwolf and others have searched long and hard and there just doesn't appear to be anyone that manufacturers them locally for commercial sale. Basically DIY guys do it themselves for their own dobs, but don't make them to sell.

The johnsonian looks really good, not exactly cheap though and *almost* getting into the realms of an EQ6 or HEQ5 or similar - so you have to weigh up your options of whether you want the convenience of a dob still (ie: get a platform), or whether you're happy to get an EQ tripod mount and have to align it, have tube rings, etc. etc.

Good luck!

[netwolf]

At present the only local option is a Johnsonian or home made. This may change soon i hope. Cause i want one.. then all i need is a Powermate and i am set to compete with Mike.

Regards
Netwolf

[rmcpb (Rob)]

Why not try a simple dob wedge for a start and see if it allows the tracking you need.

http://www.haven.k12.pa.us/orfft/wedge.html is a good site to get the idea.

[vespine]

Oh great site! This is exactly what I've been thinking about doing to my LB . I'd need an inclination angle of about 53 degrees so I'd definitely need some significant modifications to the base.

[rmcpb (Rob)]

Make sure your base plate extends under your mount AND the centre of gravity of your scope and your scope is bolted to the wedge otherwise it could be an expensive experiment.

[vespine]

Yes, I will definitely be recruiting my dad who is a very experienced do-it-all-handy-man type, has a workshop and all that. Wouldn't trust myself alone playing with a fragile $1.5k.

What I'm thinking tho is that I would motorise the az on the base to act as RA with the wedge but I don't think I'll bother motorising DEC/Alt. That would keep it easier to set up, shouldn't need computer control and all that. I'm planning to eventually put Argo Navis on it, so I don't really see that DEC motorisation would really add that much benefit, just keep DEC as 'push to'. Has anyone else done this and regretted not motorising DEC? I can't imagine so..

[rmcpb (Rob)]

Most of the wedges I have seen have only ever been auto driven in RA so once you locate the object you can then track it.

If you are serious about driving in RA then you may have to rethink the bearings in the base as some types bind a bit when they are not near level which will overload a small motor. Give it a go first with manual (pushing) tracking then progress slowly from there.

Good luck.

[Starkler (Geoff)]

Also get used to being a contortionist to get into the weird positions required to look into the eyepiece

[rmcpb (Rob)]

Originally Posted by Starkler

Also get used to being a contortionist to get into the weird positions required to look into the eyepiece

That can happen but if you use a set of rings to mount your bearings and leave the rings a bit loose so you can rotate the tube then that problem goes away. To prevent the scope from slipping through make a locking ring to sit above the mount rings and maintain the position.

[circumpolar (Matt)]

Originally Posted by Starkler

Also get used to being a contortionist to get into the weird positions required to look into the eyepiece

Well said.

The greatest advantage of the 'johnsonian' or 'Dob EQ platform' is that this never happens! Easy viewing always.
And if you are like me, one hour of tracking is plenty of time to view one object.

Brilliant invention!......But where does one get the plans?

[Starkler (Geoff)]

Originally Posted by rmcpb

That can happen but if you use a set of rings to mount your bearings and leave the rings a bit loose so you can rotate the tube then that problem goes away. To prevent the scope from slipping through make a locking ring to sit above the mount rings and maintain the position.

Rob I think the wedge idea comes to the mind of many people wanting an easy solution to RA tracking with a standard dob base.

Once you start adding rotating tube rings and addressing the shortcomming of a standard dob base designed to handle weight bearing in one direction only, you may as well start from scratch and make a purpose built tracking mount from the ground up.

[danielsun]

Originally Posted by circumpolar

Well said.

The greatest advantage of the 'johnsonian' or 'Dob EQ platform' is that this never happens! Easy viewing always.
And if you are like me, one hour of tracking is plenty of time to view one object.

Brilliant invention!......But where does one get the plans?

The johnsonian looks o.k but have you tried it or know anyone who has?
I'm keen to hear some kind of review on it.
Plus a bit expensive for me at the moment. If they were a bit cheaper i'd seriously consider one.

[Roger Davis]

When I was in Canada about 10 years ago, I attended the Astro Fest just north of Toronto. There were over 1000 attendees and over 900 scopes on the observing fields. Anyway, amongst all this there were some vendor displays and I am sure that after 10 years the company won't mind me posting this as I haven't seen anything like it since.
Behold, the EQDOB!

[rmcpb (Rob)]

Originally Posted by Starkler

Once you start adding rotating tube rings and addressing the shortcomming of a standard dob base designed to handle weight bearing in one direction only, you may as well start from scratch and make a purpose built tracking mount from the ground up.

Geoff, Yep, that is what happens, I think I am up to MkIII now but for quick RA tracking the wedge is a quick and simple modification that will work and is a great way for people to get to understand the movement and tracking of the stars. But you are right, if they want to go further then building another mount from the ground up is the way to go.