How do you steer that (Dobsonian) thing?

[Joel Shepherd]

I have a modest Newtonian on a GEM mount and am pretty happy with the ability to make fine adjustments to its position: to keep a small object in the eyepiece I just have to gently turn one knob.

Looking 12-18 months down the road, I'd like to get a bigger scope (~10 inches, maybe more) and Dobsonians seem to strong contenders.

I'm new to this sport, however, and haven't seen or used a Dobsonian first-hand. So, my question is: how do you make fine adjustments to its position: e.g. if you're trying to track with an object or center it in the eyepiece? Do you learn to gently nudge the tube around, or do the mounts come with fine manual controls, or ... ?

A go-to or push-to might be nice too, but I've managed so far without one and would like the option of continuing to do so.

Thanks -- Joel.

[jamespels]

Hi Joel, the simplest version is executed as you describe - just nudge it around. Motorised versions are around now, though, that will handle taking for you (you find the object and the scope will track it). For instance, the SW Heritage 114p Virtuoso (http://www.firstlightoptics.com/dobsonians/skywatcher-heritage-114p-virtuoso.html) has a motorised base than can take a SynScan upgrade to make it a full goto.

[jamespels]

Hi Joel, the simplest version is exactly as you describe - just nudge it around. Motorised versions are around now, though, that will handle taking for you (you find the object and the scope will track it). For instance, the SW Heritage 114p Virtuoso (http://www.firstlightoptics.com/dobsonians/skywatcher-heritage-114p-virtuoso.html) has a motorised base than can take a SynScan upgrade to make it a full goto.

[SimonfromSussex]

Hi Joel, I just nudge mine about and it's fine.

In fact I personally find the motorized versions pretty annoying because you have to wait for the scope to move to a target where as if you are moving it yourself you can really quickly shift it back and forth.

If I am looking at a big target, say the veil nebula, it's also very handy to be able to manually adjust the position rather than wait for the motor and/or over shoot the target.

Each to their own though and some people prefer a mount that does it for them. Perhaps try a manual dob at a local star party / group meet and see how you get on?

[michael.h.f.wilkinson]

I have a driven EQ mount which is great, but had a go with Olly Penrice's 20" Dob this summer. I found it very easy to nudge it around. Paraphrasing Monty Python, just go "nudge, nudge, wink, wink", without the "wink, wink"

[nicoscy]

Its very easy to move a dob around, except when trying to get a target at zenith. Then you hit the "Dob hole" as it is very challenging to gently nudge the scope when peering directly above.

Other than that it is a breeze and if your dob is fairly well balanced, you can track smoothly at high magnifications. I have been up to nearly 300x with my 12" Dob and I didn't find it difficult to track Jupiter at the time.

[hippie]

 I nudge my 10" Dob far easier & quicker than goto dob systems, Fitting a Lazy susan bearing makes life a doddle   & balancing your scope helps to, . 

http://www.qualitybearingsonline.com/lazy-susan-bearings/lazy-susan-bearing-12-inch-round/

[michael.h.f.wilkinson]

One thing I did find when piloting the Dob was I tended to swap EPs a lot less than with the driven GEM. The latter mean you do not need to worry about shifting the image when swapping EPs. In a Dob I found myself swearing at undercut EP barrels a lot more

[Floater]

Tut tut, Michael. :-)

[Joel Shepherd]

Interesting: well, those were not the answers I was expecting but I guess that's why I asked. ;-)

Are the mounts very low friction? It seems that if it took much force at all to move the scope that you'd be constantly overshooting the target.

I am hoping to go to a star party with the local astronomy group in early October and look forward to playing with a Dob hands-on there. In the mean time I'll settle for being astounded ... :-)

Thanks! -- Joel.

[m37]

I have the non goto 250px. Out of the box it was a little stiff but useable. I found a couple of tweaks helped me no end. Initially a dab of light lube on the alt bushes made it move very smoothly and some Teflon furniture pads freed up the az axis. I went a bit further and added a lazy Susan bearing to the az axis wand now very fine adjustments are a breeze. To help locate objects I got a cheap digital angle gauge for the alt axis...

http://www.amazon.co.uk/Digital-Protractor-Inclinometer-Leather-Batteries/dp/B001YJ8F8K

...and put tape round the base with 5 degree markings for the az. Works really nicely for me. I also added a strap on weight of the aerobics variety to the mirror end of the tube to balance it. Cost very little and worked out just fine.

Cheers

Chris

[Tinker1947]

My 300P Skywatcher is a GoTo, once its aligned a 2 star operation takes about a minute if you know where the stars are located, using the GoTo puts any object in the FOV of my Pentax 20mm XW, if you want to move from East to West and don't want to wait for the scope to slew, just push it round like a normal Dob, it tracks the hand movements and once you have pushed/nudged using the GoTo again it still has the 2 star align data, so once you have a object in the FOV go make a cuppa tea come back 10 minutes later and the tracking has kept it centred, It really is the best of both world, manual and auto built into one unit, just costs a bit extra........