EQ - Alt-Azimuth - Giro

[Moonshane]

Hi all

Although I can use my EQ mount well enough and it's good for tracking objects manually once located, I am finding it increasingly 'awkward' to initially locate objects as I use the refractor relatively infrequently. I am purely a visual observer and don't see this changing soon - I use a Vixen GP mount which is excellent and stable. My full kit is reasonably heavy as I have the 120mm fl1000 tube, 2" diagonal, 50mm finder and Televue eyepieces.

I think I have been spoiled by the ease of use and intuitive nature of the dobsonian mount; you just point it with the Telrad and your target is there in the eyepiece within seconds in most cases. There's no weird revolving on the mount and tube as you do it either.

Therefore I am coming to the conclusion that an Alt-Az fitted to my current wooden tripod and Vixen/Celestron tripod head (the one with the short post) may be the way forward. Most of the normal Alt-Az mounts seem to be unbalanced systems with the exception of the Vixen Custom D (is this available anymore??) and with the exception of this mount, I feel that they may not be adequate for my set-up.

The other option seems to be the 'Giro' mount which I know that some SGL members use for visual work very well. They seem slightly more expensive but looke like they will perform very well and with some weight added to a dovetail on one side would seem perfect.

Does anyone have any views on this please? Do these sorts of mounts ever come up used?

Thanks

Shane

[russ]

Hi Shane,

I use the Orion VersaGo, which is the same as the Skywatcher AZ4. I only use it with a 90mm f11 and 102mm f5 refractors and really wouldn't want to go any higher with it. The 102 with it's short tube, doesn't cause any problems. But the 90 with its 1000mm long tube is pushing the mount and i couldn't be without the Autofocuser. I think the 120 f8.3 would be too much, same length and a lot more weight.

Your best option is definitely a Giro mount, their weight capacities are much higher. There was one on UK B&S last week. Head only for £80.

[John]

I use a Giro-type mount - it's an Ambermille Az-Tech but they are not produced any more, unfortunatley. I've put mine on a CG5 2" steel tripod and it works well with both my 6" F/8 refractor and the 10" F/4.8 newtonian - it fact the mount will take both OTA's at the same time !.

With the newt I'm going to put a counterweight on the other side of the mount for smoother operation but that's really not needed with the 6" refractor.

The main issue with these mounts is tube balance - I do have to slide the OTA of the refractor forward a bit when I use my heavy 2" eyepieces.

For long refractors I reccommend the 16" HEQ5 pillar extension to get the eyepiece up to a good height - unless you prefer sitting when observing of course.

I love using these types of mounts as I favour the "plonk it down and start observing" approach

Here is the mount with my Vixen ED102SS on board (it's on a std EQ5 tripod in this shot):

[Macavity]

And here's a demo of my (largely hidden!) Giro III with an ST102. If, there's quite a bit of off-axis weight (2" eyepieces, finder scope etc.) on a smaller OTA, a few "nose weights" UNDER the tube make the "fore-aft" balance near perfect. The Giro III will work pretty much optimally with ~4lb "side to side" weight imbalance, but I usually add equal counterweights (or my MAK150) on t'other side. Then you can even watch the scope see-saw gently up and down, as the rack back and forth on the focus. <G> Apply a little friction breaking (for normal use!) and away you go...

Following John's idea, and with my pillar mount, I am also contemplating purchase of a 10" Newt OTA for a pseudo-Dobsonian setup. You can also do the "Dob-trick" of adding an Azimuth setting circle and Wixey angle gauge for Altitude readout. Easy and quiet "Push-To" technology...

[Moonshane]

Thanks all for the kind replies.

I have been doing some thinking about the Giro and they do look great and tick all the boxes for me. That said looking at the cost they are a bit pricey for me currently unless I sell my Vixen GP which I am loathe to do for the time being. However, being the scrooge that I am I got to thinking of a way round this and realised that effectively I have one already! The difference is that my current 'Giro' is set to an angle of 53 degress instead of 90 degree - yes, I mean my Vixen GP. Therefore I can in theory at least adjust the mount to 90 degrees and end up with a alt az mount (kind of), albeit slightly taller than previously. I'll try this and see how it works. This way, I can then save for a Giro mount and see if I like it before I buy.

I can then balance in both directions as normal and I know that the mount can handle what I use.

Will be interesting to see how it goes.

[John]

.... yes, I mean my Vixen GP. Therefore I can in theory at least adjust the mount to 90 degrees and end up with a alt az mount (kind of), albeit slightly taller than previously. I'll try this and see how it works.....

If you have not already read this, it might be of interest :

Astromart Reviews - The Super Polaris Mount in Alt-Az Configuration

[Moonshane]

brilliant

cheers John! I have just done exactly this based on common sense and it works!

saved me about £200!

I'll report back when I have had a chance to use it maybe with photos.

[kniclander]

silly question but how do these alt-az mounts actually move? Are they so well balanced/ engineered that you just push them very gently and they move a little bit and stop?

Reason I ask is that I use a manfroto fluid head that's actually i think made for video cameras - it just about works for astro but I have to say, it isn't great, particularly for small movements.

Is there such a thing as an alt-az mount with slowmotion controls that would suit a small scope like a skymax 127?

thanks

[Macavity]

silly question but how do these alt-az mounts actually move? Are they so well balanced/ engineered that you just push them very gently and they move a little bit and stop?

In a word, Yes. The Giro III altitude axis is simply polished stainless steel within a hard-plastic (Delrin?) sleeve bearing. The azimuth bearing is perhaps conical or roller? Either way, few mortals have ever been able to pull it apart to find out? <G> The Giro II uses lubricants, the Giro III relies totally on accurate CNC machining.

The criticism is a fair one. I am often tempted to try to fit slow motions, to my Giro III, despite. I cannot think of a ready made mount that does this well though.

[Moonshane]

I have just set my scope up (in the hallway!! as I am banned tonight after two nights on the trot) with my 'modded' Vixen GP Mount and I am falling back in love with my refractor again.

I can see already it's going to be so much easier and more enjoyable to use for visual work. The advantage of this is that I can easily 'convert' back again to the standard GP.

I may start another thread to show how I did it - took about 10 minutes.

Here's some quick pics - just got to stick the GP logos/altitude scale back on.

Due to the tab on the altitude adjuster I could not get the mount to sit perfectly vertical but it does not really affect anything - I may try and sort this out in due course - it's close enough for now.

On fine controls, I took all mine off as I'll use it like a dobsonian mount and they looked like they'd restrict movement occasionally. It's well balance and will just need a tweak here and there when I use heavier eyepieces. Not hard as the OTA is lower than before. Need to add my optical finder too and the GP 'control/motor box'.

Looking forward to a play soon.

I think if I didn't have the GP, I'd buy a Giro iii but as I do, I really don't see the need now.

cheers again

Shane

[kris h]

That setup looks Awesome John

[GazOC]

Nice setup John. I did something similar with a EQ2 a while back and it worked well.

[Macavity]

I sometimes, rather wikedly, wonder, if you had the "Synscan" GoTo version of Skywatcher EQ mounts and told the software you lived at the North Pole, would it work? [semi serious]

[John]

I have just set my scope up (in the hallway!! as I am banned tonight after two nights on the trot) with my 'modded' Vixen GP Mount and I am falling back in love with my refractor again....

Thats looking excellent

Hmmm - I wonder if the CG5 would do that

[Moonshane]

hi John

Looking at this Astronomy Boy: CG-5 Mount Improvements the CG-5 has the same construction as the GP so it would seem to be the same process. Undo the big nut and then put it back together vertically. I had unrestricted movement when testing my set up and I am really please I 'went for it'.

Looking at the photo of my rig, I think I'll paint both of my counterweights black - the electric blue one looks a little out of place - maybe I'd get away with just the black one though in this format - I'll see how it goes.

[Helen]

Is there such a thing as an alt-az mount with slowmotion controls that would suit a small scope like a skymax 127?

thanks

Yep, Vixen - Vixen Porta II Mount

Helen

[John]

Yep, Vixen - Vixen Porta II Mount

Helen

Or even a humble AZ-3 - I've had a Celestron C5 on one of those with no problems as it's a short tube.

[kniclander]

Or even a humble AZ-3 - I've had a Celestron C5 on one of those with no problems as it's a short tube.

aaah thanks - I just need to find one without a tripod