Alt-Azimuth Balance

[johninderby]

Vibrations can be reduced to a level that they don’t interfere with viewing and that’s about it. Minimal rather than zero is the word.

All this talk of vibrations made me think of this. 😁

 

Edited October 30, 2019 by johninderby

[Saganite]

3 minutes ago, John said:

Reconciling that with owning an F/15 refractor is must to be tough !

I've yet to try a mount that gives me zero vibrations and immediate damping with my long refractors over 4 inches in aperture. Even the EQ6 / Meade Giant Field tripod (3 inch steel legs !) didn't quite do that.

 

 

It is indeed John. The pier, plus heavy duty dovetail plate and NEQ6, has reduced it to about 2 seconds maybe a little more and I have had to accept that with such a long moment arm, that is about as good as I will get, but in an attempt to eradicate movement of the image upon focusing at high powers, I am fitting the Moonlite High- res stepper motor. I will report my trials and tribulations eventually....

[Rob Sellent]

@Mark at Beaufort, you're a genius. You've gone and mashed two potatoes with one fork! Not only have you answered my enquiry in another thread about the HDAZ which is in fact a SkyTee 1 but have thoughtfully added to this one. Thank you .

Mark, the first pic you shared shows your gorgeous 102 apo and its balance point is just about where I'm balancing my own 102 frac. There's that play of an inch before the rings reach the focusser's flange. Putting a heavy 2" eyepiece or binoviewer in the focusser and I just know that the inch isn't going to be enough to obtain balance. Therein lies my concern.

Do you think a SkyTee 2 would allow the scope to be shuffled 'back' towards the observer thus gaining a few inches whilst still maintaining a fluid balance?

19 hours ago, Saganite said:

go for something like the Skytee/ Ercole, or Berlebach castor...virtually zero damping time

 

17 hours ago, Louis D said:

put Sorbothane pads under each tripod foot to quickly dampen vibrations

 

2 hours ago, Saganite said:

also change to a Berlebach tripod,

I probably didn't make the OP clear Unfortunately, it's not a case of wobbles or vibrations at high mags. The mount and tripod handle the Vixen well. It's trying to reach a balance where I'm not taking the scope's rings right back to the focusser's flange with just a 10x50 finder, Moonlite focuser, a 2" TV diagonal and Delos eyepiece, for example. My concern is that loading the focusser with a 2" eyepiece or binoviewer and balance will become virtually impossible 

The SkyTee 2's TS AZ5 clone and possibly an Ercole (not sure if this has any advantages over the SkyTee) look good options but only if they can deal with this pestering balance issue.

Thanks again for all your help

Quick Edit - Other Possible Options

• Remove the Moonlite - don't fancy doing this for it allows me a better snap-to focus than the original - some what old and worn - original focuser
• Change the diagonal - that's a cheaper option going from 2" to a 1.25" but will that sort out the problem?
• Don't use Delos type eyepieces - again an option but I do like the view they give and in my older age, I'm not a fan of small FOV orthos/plossls
• Get rid of the finder - I've gone down to a 8x50 and a 6x30 but this really makes very little difference. If I got rid of a finder entirely, I'd still need a heavy 2" wide field to star hop around which is going to be just as heavy. 
• Don't bother with az mounts - would an EQ5 handle balance better?

Edited October 30, 2019 by Rob Sellent

[Stu]

A couple of comments from me. I've always found that using two scopes on these mounts makes life easier from a balance and stability point of view. It is easier to reach balance because you've got both scopes to play with and I think the extra mass (or perhaps moment of inertia?) somehow makes the rotation easier to control and better damped.

Second point is that it does seem that mounts with slo motion controls are that bit more tolerant than those without. The Ercole is excellent, but does need to be precisely balanced with the clutch tension set just right. Those with slo motions can be set so they can be moved manually, or via the slo mos and that avoids sudden movement when loosening a clutch. The SkyTee 2 seems to perform better than its somewhat agricultural engineering (compared with a Ercole) suggest it should. The AZ100 seems to combine lovely engineering with the benefit of slo motion controls.

Lastly (sorry that is three points now ), don't underestimate the importance of the tripod in the overall equation. My tiny Giro-WR can take surprising loads when mounted on a 2" stainless steel tripod, particularly when I upgrade the shaft to a stainless steel one. This adds to the weight though so I keep it as standard with only one saddle for travelling. The tripod really helps with stability but can equally undermine a seemingly good mount.

[Rob Sellent]

That's brilliant, @Stu and thank you

Judging by the overwhelming support in this thread the SkyTee 2/TS-AZ5 looks like a sure footing and probably better to get this with an EQ6 type mount or UNi 28 for extra support. This set up will be solely used in the garden/patio so I'm not too fussed about weight. For a more travel-friendly option there's always  the HDAZ or AZ4 for more 'grab n go'. The AZ100 looks a cracking mount but its purchase and necessary tripod would bump the budget beyond what I'm comfortable with and I'm sure with a little thought and tweaking, I can get this relatively light 4" sorted

Thanks again, Stu

[Mark at Beaufort]

Rob I thought showing this photo of a SkyTee 2 mount might be better than writing a statement. 

[CraigT82]

1 hour ago, Rob Sellent said:

I probably didn't make the OP clear Unfortunately, it's not a case of wobbles or vibrations at high mags. The mount and tripod handle the Vixen well. It's trying to reach a balance where I'm not taking the scope's rings right back to the focusser's flange with just a 10x50 finder, Moonlite focuser, a 2" TV diagonal and Delos eyepiece, for example. My concern is that loading the focusser with a 2" eyepiece or binoviewer and balance will become virtually impossible

To be honest I think you just need to add some weight to the front of the scope! A velcro ankle weight would cost a few quid, and do the job nicely, plus it's quickly removable and without marking the tube

[johninderby]

Ypu can use an EQ6 tripod with the Skytee but need a Geoptik EQ5 adapter to do so. The Celestron CG5 tripod With the 2” legs will fit directly but very hard to find. 
 

EQ6 tripod with a Berlebach spreader fitted.

[Stu]

Looks nice John!

@Rob Sellent ignore the title but this thread shows a front counter balancing device I concocted using various bits and pieces I had. It clamps to the front of the Vixen Dovetail and allows you to balance front to back, but also to offset longer eyepiece stacks or binoviewers, making perfect balance possible even up towards the zenith. I could have clutched completely undone and this setup would stay put in any position.

 

[AdeKing]

1 hour ago, Stu said:

Looks nice John!

@Rob Sellent ignore the title but this thread shows a front counter balancing device I concocted using various bits and pieces I had. It clamps to the front of the Vixen Dovetail and allows you to balance front to back, but also to offset longer eyepiece stacks or binoviewers, making perfect balance possible even up towards the zenith. I could have clutched completely undone and this setup would stay put in any position.

 

I have also concocted one of these with Stu's assistance in identifying the component parts. 

I tend to use it on my Ercole Mini when I'm using binoviewers and it works really well. It helps a lot with balancing the ZS66 and BV setup as the tube of that little setup is very short (388mm f/l) and I find balancing it a challenge at the best of times. 

 

[Ben the Ignorant]

On 28/10/2019 at 14:18, Rob Sellent said:

I've read that tryng to tie bean bags to the lens end of the scope might do the trick, but this just seems like too much bother 

Making some sort of counterweight is the only solution I know to balance problems.

[Science562h]

joe, I find it very odd, that you have a Takahashi & a cheap $100 range CG-4 mount. It doesn't have GOTO, slewing or autoguiding.