Breeze and scope size / length

[Alan White]

I have asked about this other ways, but I keep getting breeze on clear nights and my ED100 is moved in the breeze on any mountsI have used.

So what scope can buy used in a breeze?

Shorter FL smaller aperture?

Mak or similar?

or stuff it I am packing up and having a tea / beer / going to bed?

 

Edited May 26, 2017 by Alan White

[nightfisher]

A Mak 150 ? can you put some tension on the giro mount?

[laudropb]

Hi Alan. When you say your scope is moving in the breeze do you mean that the image at the eyepiece is unsteady or does the actual scope swing in the breeze ?

I have an ED 120 on a Skytee 2 mount and it's very steady unless its blowing a gale. Perhaps it's the mounting plates. I changed over to ADM plates and they certainly are much more secure.

Edited May 27, 2017 by laudropb

[Alien_Photons]

Try a wind break, a gazibo even you can leave that up, different location.

I cant imagine a 100ED on an EQ6 suffers much with a breeze. 

[Alan White]

Thanks so far folks, to be clear,

ED100 do pro on Giro Ercole with AdM plate on a 2" steel leg cg-5 tripod, it's very solid.

Its not the mount moving, it's the tube vibrating due to the length, I am on a hill and it gets breezy.

I know it's not a proper hilll or proper wind, it's only Essex after all, but the viewing is turned all the same.

Aim is for a skyshed dome over the summer to shelter in, but I was asking as I sometimes view from the drive.

[brantuk]

Do you have the mount well balanced - the Giro Ercole can take 17.6 lbs each side so whatever your scope weighs needs counterbalancing with the same weight on the other side. Sounds obvious but it's just a thought....

Alternatively it could be ground shake from walking around the rig which can sometimes be settled with these:

https://www.firstlightoptics.com/misc/celestron-vibration-suppression-pads.html

One other thought is what magnification are you using when you notice the vibration? The higher the magnification the less stable the image is - even the tiniest shake gets magnified with the shortest eyepieces.

Hth

Edited May 27, 2017 by brantuk

[Alien_Photons]

Personally I have moved to a medium length rail for the rings on my 100mm refractor it helps brace the tube as a whole considering 90% of the weight is at the ends. This is abvious. Whats not so obvious is that vibration occurs around the weakest or smallest connection. Thus might be between the head and tripod axels and mounting plates. Etc etc etc. I recently had vibrations from the RA drive and it turned out to be the DEC axel. You might surprise yourself by loosening the clutches one at a time and checking if the vibration stops then retightnening and trying the next connection on the mount. I am not suggesting you try this with the saddle or the rings by the way.

Another trick is try shortening the legs. There is often a relationship between leg length and low frequency vibrations. This being the case you could add a head extention.

The solution is often simple diagnosing the problem can be the tricky bit.

Good luck and keep an open mind about it.

Edited May 28, 2017 by Alien_Photons

[nightfisher]

I have the ED120 on CG5 tripod with Giro II mount and find it very stable, and i am a fussy one when it comes to mounts

[Alfian]

I have the ED100 with an AZ4 and a pillar extension. The latter lifts the EP to a more comfortable position (with the 1.75" steel leg tripod at a lower more stable height)  but the pillar also adds considerable weight which gives a really solid feel to things.  With this I've used the ED100 at 150x with little trouble, and this is with the standard dovetail and tube rings. I live on an exposed  hillside  a 1000 foot up and the there is usually some wind and often a lot! There obviously does come a point where it becomes pointless too go out.  I would have thought the Giro/CG5 combo  would be better than the AZ4, so surprised you are having too many problems. As has been said, magnification will amplify the issue, so could see vibes being more obvious at 200+.

In terms of other scopes, I've been tinkering with my Mak127 on a home brewed Tal1 Alt/Az setup on a fairly gusty night (small trees blowing around a bit) I had it working OK at 120x with vibration kicking in with strong gusts, but settling down in not much more than a second.  If you were to swap scopes, A 127/150 Mak on your mount setup should be very stable, though it seems a shame to give up on the ED100 as its a fine scope. Perhaps a pillar extension would be the answer.

[Alan White]

Again thanks guys.

I am sure it's not the mount at all, solid as a rock and settles in way under a second, the problem is only when it's windy, perfect when still or just a light breeze.

Just to be clear, the scope tube literally shakes in a breeze, so the longer vixen bar may work by stiffening the scope as suggested, perhaps that's longer tube scope for you.

I love my ED100 for the views, but equally as a mainly lunar and planetary visual observer, thought a shorter tube such as a mak might be a solution.

Longer Vixen rail is the cheapest option to try then, so let's see what's up for sale.

Perhaps it's just the wind local to my location and the observatory will solve it.

Edited May 27, 2017 by Alan White

[mikeDnight]

19 hours ago, Alan White said:

I have asked about this other ways, but I keep getting breeze on clear nights and my ED100 is moved in the breeze on any mountsI have used.

So what scope can buy used in a breeze?

Shorter FL smaller aperture?

Mak or similar?

or stuff it I am packing up and having a tea / beer / going to bed?

 

Hi Alan,

A 127 Mak is an amazing scope that would probably be less affected by tremor, though you'd need a dew shield that would still catch the wind. You could also mount the scope on a pier embeded in concrete, or better still, build a small observatory to shelter you from the wind. 

A Hargreaves strut would definitely dampen any vibration in the tube caused by wind, and it would be the cheapest option.

Mike

[Alan White]

Thanks Mike, now I have Googled what a Hargreaves Strut is, one problem, I am using a Giro mount.

I am still convinced the mount is fine, the tube vibrates at the optic end in a breeze, the tube is flexing marginally and the scope has a vibration. It may be that I am observing in what I consider a breeze for planetary and lunar when others would move on to lower magnification targets or pack up of course.

I think my plan for an observatory in late Summer will resolve a lot of the problem in itself.

The pier was for next year, but I may bring that forward and look at that sooner rather than later.

Edited May 27, 2017 by Alan White

[SonnyE]

All this talk of wind makes me ask if maybe a change of diet might help......

[Mr Spock]

I've found most flexure, and hence vibration, comes from the dovetail. If you are using a Vixen type dovetail that's where the vibration is coming from. They are not nearly solid enough for any large scope - large meaning size not aperture.

[Alan White]

Mr Spock, are you saying buy a longer dovetail?

 

[Stu]

2 minutes ago, Alan White said:

Mr Spock, are you saying buy a longer dovetail?

 

I think, if you don't have one already, then a longer ADM Vixen Dovetail would be worth a try. Solidly machined and with the rings further apart it should help.

How solid are your rings? A decent CNC pair may also improve things.

Michael may have been suggesting moving to a Losmandy type Dovetail but that would involve changes to clamps etc so might form a stage 2 if stage 1 doesn't work!

[Alan White]

Hi Sti

I am using the supplied Skywatcher rings and dovetail.

The longer dovetail as it increases the length of tube clamped sounds a good stage 1.

 

[mikeDnight]

Hi Alan,

May be you could try your scope on a Vixen GP mount if someone near you would be willing to help out. They are solid and if there's any vibration it would be from the tripod.  It might just tell you where exactly the problem lies. I feel certain that your scope is not flexing, so it is either the mount or tripod where the movement is coming from. The dovetail clamp is a prime suspect, but other weak points may be the tripod head or even the altitude axis moving within the mount head. The length of the altitude arm is another possible weak link where vibration might occur. Even micro movements at any of these points will be amplified many times in the eyepiece.

Mike

[Mr Spock]

Mr Spock, are you saying buy a longer dovetail? 

No. I made the switch from Vixen to Losmandy for this reason. The Vixen doesn't have a wide enough base to be flex free.

[CraigT82]

Yeah I'd say make the switch to losmandy dovetail if your conditions are regularly windy. Not cheap granted, but will be a 'keeper' for future scopes.... and get a longer one to put some more distance between the tube rings. Also could try removing the dew shield if it's not strictly necessary? (not sure if the one on the ED100 comes off?)

[John]

3 hours ago, Alan White said:

Hi Sti

I am using the supplied Skywatcher rings and dovetail.

The longer dovetail as it increases the length of tube clamped sounds a good stage 1.

 

I found longer dovetail bars allow more flex when I've used them with long, heavy refractors. A shorter, wider DT bar eg: a Losmandy, is an improvment. I've also found the William Optics Vixen DT bar with it's wide base and strong sectional design works better than a conventional DT bar and much better than the standard Skywatcher types:

https://www.firstlightoptics.com/dovetail-bars/william-optics-vixen-compatible-long-dovetail-plate.html

I use one of the above with my 130mm F/9.2 triplet refractor.

Edited May 28, 2017 by John

[Alien_Photons]

18 minutes ago, John said:

I've also found the William Optics Vixen DT bar with it's wide base and strong sectional design works better than a conventional DT bar and much better than the standard Skywatcher types:

That's a good idea. I might put my WO base on my bigger refractor. Just because I can. Nothing like an little experimenting.

[Stu]

Those WO wider dovetails do look more rigid, can't see any reason to go to Losmandy for a 100ED I must admit.

I've not noticed flex in the ADM dovetails I've used, the solid machined ones I mean. Certainly the cast Skywatcher ones will flex.

[CraigT82]

5 minutes ago, Stu said:

Those WO wider dovetails do look more rigid, can't see any reason to go to Losmandy for a 100ED I must admit.

I've not noticed flex in the ADM dovetails I've used, the solid machined ones I mean. Certainly the cast Skywatcher ones will flex.

I'l give you a reason - future proofing.  Can be kept and used for bigger, future scopes.

[Alan White]

Well that's a lot more mixed input, thanks all.

I have used it on the GP2 mount, now owned by one of those who has input, the scope did the same in a breeze as it has done on every mount it's been on.

I get a lot of breeze / wind here, not due to diet as suggested, but I am about 3 miles or less from the Thames Estuary and so evening sea breezes are common.

My tripod is like the proverbial brick toilet, the Giro Ercole as is well known here somewhat solid and it's all well balanced.

I have always felt that the rings and dovetail are a weak link for me in my situation, not for the scope for most, CNC rings I am struggling to find in the correct size, any pointers please.