Leveling a Pier: who's right ?

[Vox45]

I am looking for a pier for my permanent observatory build. I found these 2 piers that fit my needs but they have a different design:

Altair Skyshed 8 inch Observatory Pier (Heavy Duty w anti-vibration fins) designed with a leveling plate

https://www.altairastro.com/altair-skyshed-8-inch-observatory-pier-heavy-duty-w-anti-vibration-fins-441-p.asp

and

Pulsar Anti-Vibration Observatory Pier v2 without a leveling plate

https://www.firstlightoptics.com/pulsar-observatories/pulsar-anti-vibration-observatory-pier-v2.html

I've heard over the years that your mount doesn't have to be perfectly leveled as it will mechanically be leveled when doing the polar alignements.

here's what Pulsar is saying about the leveling plate: 

The adjustable platform myth : This myth began, we suspect, because early DIY pier designs were based on a poured concrete or wooden pillar, requiring an adjustable platform.  An all-welded pier does not.  These DIY designs spread via social media to such an extent that today even some commercially available piers unwittingly include the same adjustable platform! 
  
The myth is that astronomy piers need an adjustable platform to achieve a perfect level.  It is not true because a GEQ mount's RA axis is polar aligned, so it is independent of the pier's top plate.  This is fortunate because fitting a mount to an adjustable platform, which is in turn fitted to some stud bolts, defeats the purpose of having a solid all-welded pier.  But what about Azimuth rotation?  This isn't necessary either because astronomy mounts have integrated azimuth adjustment (it is necessary to know where North is when fitting a pier to its concrete base, but that isn't difficult).

But here's what Altair is saying about this:

Levelling and rotation is important for good GOTO and easier, more accurate polar alignment:  All major mount manufacturers recommend setting up an Equatorial or Alt Azimuth mount as level as possible, and aligned to the North/South axis. Without accurate levelling Equatorial Mounts are difficult to polar align The only way to ensure your mount is perfectly level is with the four 16mm thick steel threaded adjustment rods, which allow small incremental adjustments with a spanner once your scope is mounted. Don't fall for cheaper designs which don't allow rotation or rely on "shims" (basically washers) for accurate levelling. When you get that dream rolloff observatory or dome built, or make your own, this is the only solution to get 100% right designed by astronomers. We have replaced many piers from 3rd parties which have suffered various problems from corrosion, to a frustrating inability to level or rotate them in Azimuth.

What are your thoughts on these 2 opposite take on the leveling issue ? Is it purely a marketing strategy and it won't make any difference to the average astronomer ? I find that Altair "only way" and "only solution" (emphaisis mine) is a bit arrogant tbh.

I like the Pulsar one because of the "Owls Nest" and cable access holes. 

I suspect that with the material that I use and the poor seeing, I would never see the effect caused by vibrations, especially since I won't be standing anywhere near the mount and the base will be isolated from the observatory.

 

Edited May 3 by Vox45

[inFINNity Deck]

Hi Vox24 (is that your real name?),

both have some wisdom and truth in it. I am a hydrographic/land surveyor for 35 years now and know a fair bit about setting up all kinds of optical instruments on tripods, piers, etc. In addition I built my own domed observatory six years ago. Setting-up instruments on a level base is always easier than on a non-level base. But as mentioned, there is no need for the base to be level.

In astronomy doing a polar alignment is easier on a level base simply because when the base is level the altitude of the mount does not change when the azimuth of the mount is changed. On a non-level base the altitude will change and as a result doing polar alignment may require a few more iterations in that case.

So, for convenience, it is good to have the base level, but that is all there is to it.

Nicolàs

[apaulo]

If care is taken when setting up any sort of pier, to ensure the top is level,  any leveling device is not needed. 

[Vox45]

50 minutes ago, inFINNity Deck said:

So, for convenience, it is good to have the base level, but that is all there is to it.

Nicolàs

The drawback of a leveling platform is that you rest your whole setup on 4 bolts but I've seen some people argue that those for bolts are rock solid... I agree with your point, I don't think I would be able to see the difference with my light setup and the seeing I usually get any vibration would be drowned anyway.  So, I'll go with the one that I think would be more convenient for me, the Pulsar with the Owl nest  

[saac]

I never paid any real attention to leveling my pier beyond a cursory care while laying the pier base.  I have never had difficulty in either polar alignment, go to precision or tracking. Levelling is more relevant when using an alt az mount but irrelevant largely when using a GEM mount.  However some people like to fuss over the smallest detail and for them that is part of the enjoyment - hence the legend of the requirement for a 1 cubic metre concrete pier base. Go figure. 

Jim 

[inFINNity Deck]

19 minutes ago, Vox45 said:

The drawback of a leveling platform is that you rest your whole setup on 4 bolts but I've seen some people argue that those for bolts are rock solid... I agree with your point, I don't think I would be able to see the difference with my light setup and the seeing I usually get any vibration would be drowned anyway.  So, I'll go with the one that I think would be more convenient for me, the Pulsar with the Owl nest  

Those four bolts (six in my pier) are also referred to as a "rat-cage" (or "rat-box" as you called it yourself) of which is said that it would ruin the stability of your set-up. My rat-cage is very low, but friends of mine have 'decent' rat-cages and no issues at all. As long as the bolts are thick enough and the set-up properly balanced, the rat-cages are fine (IMHO that is).

Nicolàs

[Vox45]

5 minutes ago, saac said:

I never paid any real attention to leveling my pier beyond a cursory care while laying the pier base.  I have never had difficulty in either polar alignment, go to precision or tracking. Levelling is more relevant when using an alt az mount but irrelevant largely when using a GEM mount.  However some people like to fuss over the smallest detail and for them that is part of the enjoyment - hence the legend of the requirement for a 1 cubic metre concrete pier base. Go figure. 

Jim 

I've read somewhere that the 1 cubic meter requirement came from the 1st DYI pier base that were mostly done in colder region in the US where the frost line can be quite deep, so footings needed to be placed below this line to prevent them from heaving or shifting due to the freeze-thaw cycle. It then became "a standard" even in countries where it never really gets cold in the winter. Not sure if it's true but it would explain the overkill

[Vox45]

5 minutes ago, inFINNity Deck said:

Those four bolts (six in my pier) are also referred to as a "rat-cage" (or "rat-box" as you called it yourself) of which is said that it would ruin the stability of your set-up. My rat-cage is very low, but friends of mine have 'decent' rat-cages and no issues at all. As long as the bolts are thick enough and the set-up properly balanced, the rat-cages are fine (IMHO that is).

Nicolàs

OMG you've unhearthed a thread I've totally forgotten about ! That's almost 8 years ago   time flies. I've learned a lot by reading my own thread ! lol

Back then I was in the process of planing the build but I had to move to the city and never got the chance to go through with it... Now I am back at it  

[saac]

16 minutes ago, Vox45 said:

I've read somewhere that the 1 cubic meter requirement came from the 1st DYI pier base that were mostly done in colder region in the US where the frost line can be quite deep, so footings needed to be placed below this line to prevent them from heaving or shifting due to the freeze-thaw cycle. It then became "a standard" even in countries where it never really gets cold in the winter. Not sure if it's true but it would explain the overkill

 

I think this overkill and fascination with numbers and specification is a very male thing and it's often found in hobbies (audio, photography, gaming)  where it bring out an obsessive nature.  A 1 m cubic block of concrete it a prime example. We will also fuss over tracking accuracy comparing phd plots and and periodic error correction graphs without really considering the most obvious limiting factor of all , seeing!  Not a criticism, for some that type of thing is really part of the enjoyment.  My approach is to ignore received wisdom, do it and see what happens. 

Jim 

Edited May 3 by saac

[Vox45]

8 minutes ago, saac said:

We will also fuss over tracking accuracy comparing phd plots and and periodic error correction graphs without really considering the most obvious limit factor of all , seeing!

I couldn't agree more  

[ollypenrice]

Altair are wrong. They say, 'All major mount manufacturers recommend setting up an Equatorial or Alt Azimuth mount as level as possible,' but they don't. Takahashi mounts have no facility for leveling on their expensive GEM mounts. The only advantage presented by a level mount comes when drift aligning when a level mount has no interaction between axes but a) will you be drift aligning? and b) the effect is trivial.

It is folly to introduce flex into a mount by making an adjustable top for it. It serves no purpose.

The usual problem is that you need to get a tool under the mount to attach it to a pier but that is bad design on the part of the mount designers. Modern mount designs are now trying to avoid this.

Olly

[Ouroboros]

The advantage as I see it as someone who sets up each time is that when I plonk the mount down it’s good to start with the mount  roughly level because it means the declination won’t be too far out when I start polar aligning. But it’s not necessary, no. On the other hand, I guess you wouldn’t want a pier looking too wonky would you?  

[saac]

1 hour ago, Ouroboros said:

. On the other hand, I guess you wouldn’t want a pier looking too wonky would you?  

Yes the aesthetics of the amateur astronomer's rig is very important. This is self evident in the way telescope and mount manufacturers have embraced bright primary colour hard anodising.   Now here's a thing, I wonder how my fellow amateurs "dress" while astronomising (yes Olly I know that is not a real word).  This could be a whole new thread - "astronomy attire for the evening session and twilight hours and even formal (black tie) astronomy attire when you pass the port to the left  

Jim 

[andrew s]

You pays your money and takes your choice.

Regards Andrew 

[saac]

I bet somebody somewhere has one of those and levelled it. 

Jim