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Equipment Discussions >> Mounts

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ur7x
professor emeritus


Reged: 01/08/12

Pier Height Suggestions/tips new
      #5840068 - 05/04/13 12:43 PM

So my machinist is making me a pier top out of a chunk of billet aluminum. That will go on top of a 7" diameter steel "post".

The OTA and mount that will be used are a C9.25 and a CGEM.

The question, for a 6' tall guy with similarly tall grown kids, What is the best height to have the pier at? Is there any rule of thumb for this?


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shawnhar
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Reged: 06/25/10

Loc: Knoxville, TN
Re: Pier Height Suggestions/tips new [Re: ur7x]
      #5840162 - 05/04/13 01:55 PM

My pier is 3 feet and that's 2 feet too short, can't get anywhere near zenith, even sitting on a chair bent over it's a pain. I'm 5'9. It was fine with the fork mount, but that gem throws the eyepiece down below the height of the pier.

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mclewis1
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Reged: 02/25/06

Loc: New Brunswick, Canada
Re: Pier Height Suggestions/tips new [Re: ur7x]
      #5840518 - 05/04/13 05:59 PM

Shawn's concern about eyepiece height when viewing the zenith is probably the biggest issue. Let your current comfort and usage of the CGEM on it's tripod be your guide. Get a tape measure out when you are observing and get an idea about the extremes of viewing positions. Also note situations that you'd like to improve on.

Do you want the eyepiece to be a bit higher than it is now when viewing the zenith? (do you have an adjustable chair that will let you sit down low? ... if not consider this as it's probably easier/cheaper than modifying a pier.
Going the other direction, can you observe down to your horizons? This will dictate the total eyepiece height. Having everyone at or above 6' will make this a little easier.
Will you ever consider a big refractor for your mount? ... if so it will likely make the zenith issue worse.
Consider a two piece pier topper with 5/8 or 3/4" threaded rods between the two pieces. This way you can size the pier on the low side and use the two piece top to adjust the final height.


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ur7x
professor emeritus


Reged: 01/08/12

Re: Pier Height Suggestions/tips new [Re: mclewis1]
      #5840636 - 05/04/13 07:39 PM

Thanks to both that is great advice.

Right now I typically put the CGEM in the yard on the factory tripod at its lowest (about 30" to the top of the base/head flat spot) I have never had an issue with height as I have a very nice 2" diagonal and the micro focuser easily swivels. So I can get a "comfy" spot with very little effort for the whole family with the tripod "low"

But honestly I have never given this any thought. Now that I consider this, the low setting kind of places the OTA in no man's land. Too short to observe standing (without bending over)... too high to observe on a stool or sitting.

I was hoping this was going to be a simple thing like "cut the hockey stick where it meets your chin with skates on" or like "an easy riding surf board should be about 5" longer than you are tall."


How far off of the ground do you all normally try to have the eyepiece for your most comfortable viewing with say the telescope at Polaris? What about for star parties? same?

Oh and the C925 will likely be my last scope. There is no monster refractor in my future... not and keep the same wife.


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Spacetravelerx
Carpal Tunnel


Reged: 12/23/12

Loc: New Mexico
Re: Pier Height Suggestions/tips new [Re: ur7x]
      #5840655 - 05/04/13 07:58 PM

I am curious on this too. Viewing Saturn the other night I had to get on my hands and knees!

Is 5' the right height for a pier? 4'? I know when using cameras height does not matter. But, for visual and using a GEM I am more and more convinced the mount has to be higher up. Is there a table/chart referencing pier height to human height average comfort level?

For my fork mount scope this is easy. The GEM appears to be a different story.


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Spacetravelerx
Carpal Tunnel


Reged: 12/23/12

Loc: New Mexico
Re: Pier Height Suggestions/tips new [Re: ur7x]
      #5840656 - 05/04/13 07:58 PM

I am curious on this too. Viewing Saturn the other night I had to get on my hands and knees!

Is 5' the right height for a pier? 4'? I know when using cameras height does not matter. But, for visual and using a GEM I am more and more convinced the mount has to be higher up. Is there a table/chart referencing pier height to human height average comfort level?

For my fork mount scope this is easy. The GEM appears to be a different story.


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etsleds
sage
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Reged: 11/14/09

Re: Pier Height Suggestions/tips new [Re: Spacetravelerx]
      #5840685 - 05/04/13 08:24 PM

At the hazard of actually making recommendations...

I personally like having the eyepiece range from 3 to 5 feet off the ground. Hard to manage for all the various scopes & mounts I use, but that for me generally means my cats on GEMs are on 42" platforms and my refractors are on 48-54" (depending on the length). Your preferences will likely vary, but I'd be surprised if recommendations are dramatically off.

Good luck and congrats on the permanent mounting!


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woodworkt
sage
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Reged: 06/07/06

Loc: Northern Virginia
Re: Pier Height Suggestions/tips new [Re: etsleds]
      #5840825 - 05/04/13 10:06 PM

One idea... The next time you're set up on the tripod, measure the height the eyepiece ends up atponted to zenith, and then again pointed to horizon. That will give you the range of differences you have to consider. With a C9.25, it shouldn't be a wild swing even with a GEM.

After that, the goal may be to have the average between the two end up at the most comfortable height for you, provided neither the top nor bottom of the range is unworkable... You may be able to calculate that from your current setup, or from the specs for your mount. But I think most people do most of their viewing somewhere in that mid range.

That process helped me end up at what seems like the right height for my own portable pier back 7 or 8 years ago, and it's hopefully the last I'll have to buy, even if I were to switch scopes or mounts.

Good luck,
--Ken T.


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gavinm
Carpal Tunnel


Reged: 08/26/05

Loc: Auckland New Zealand
Re: Pier Height Suggestions/tips new [Re: Spacetravelerx]
      #5841164 - 05/05/13 05:54 AM

Quote:

I know when using cameras height does not matter.




Disagree. Had a pier made that ended up about 5 foot, so once the telescope and wedge was installed, I needed a small ladder to do anything, from rotating the camera to looking through the finder scope. Had one choice - cut the pier down... so I decided to take the easy option and lift the whole observatory up a foot. Vast improvement.. nothing higher than about shoulder height.. I only do CCD work BTW.


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ur7x
professor emeritus


Reged: 01/08/12

Re: Pier Height Suggestions/tips new [Re: gavinm]
      #5841456 - 05/05/13 11:12 AM

I completely agree with this too.

The steel "pipe" that I got at the local metal "traders" place is almost exactly 48" tall with a 1/2" thick flat top. and a large square "bolt down plate" looks like it might have been a security bollard in a former life.

The Aluminum adapter with its locking knob and leveling bolts will add at least 6" on top of that. Even if I plan to do most of my work with a Camera, I will likely be moving the mount head in and out a couple of times a season and I'm not a fan of leaving the OTA outside for any length of time either.

The CGEM mount head, at the best of times is an awkward heavy beast. "clean and jerking" that up to a mount base 50 some inches up has its own set of trade offs. trying to clamp down the OTA 5' up in the air is even more scary.

So how far down did you cut your pier? Where do you have it now?


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CounterWeight
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Reged: 10/05/08

Loc: Palo alto, CA.
Re: Pier Height Suggestions/tips new [Re: ur7x]
      #5841570 - 05/05/13 12:25 PM

Part of it all depends on if you'll be attaching a levelling plate type assy, you need to subtract height for that. I'd also repeat and advocate to measure with / using your observing chairs and physical needs with scope at 45* should give some safe numbers.

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gavinm
Carpal Tunnel


Reged: 08/26/05

Loc: Auckland New Zealand
Re: Pier Height Suggestions/tips new [Re: CounterWeight]
      #5841862 - 05/05/13 03:20 PM

I didn't cut it.. I cut the piles of the observatory and inserted more wood. Lifted the whole thing up about a foot and a half on jacks..

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ur7x
professor emeritus


Reged: 01/08/12

Re: Pier Height Suggestions/tips new [Re: gavinm]
      #5842278 - 05/05/13 07:15 PM

Very interesting... I've been playing with my scope in the backyard today... it is a beautiful day and looks like we are going to get some super nice seeing tonight for Saturn...

Anyway after lots of fiddling I came to the decision that the best height for me and my kids will be about a 42" pier... Pretty much were yours ended up after you lifted your observatory. It is a little low at zenith (you could sit in a chair) and horizon is a conferable stand... On top of that, it is about as tall as I dare lift the OTA.

Thanks again to all for your input, for me it looks like a 3' 6" pier will be the ticket.


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Patrick
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Reged: 05/16/03

Loc: Franklin, Ohio
Re: Pier Height Suggestions/tips new [Re: ur7x]
      #5842641 - 05/05/13 10:59 PM

Quote:

The question, for a 6' tall guy with similarly tall grown kids, What is the best height to have the pier at? Is there any rule of thumb for this?




I use the rule of the belly button. Seriously, I made my pier height about 3" above my belly button (I'm 6' tall...)! I'm not sure exactly how high that is, but it's working out fine for me . Like you I also mount a CGEM, and put a C8 on it. That puts the eyepiece at a comfortable height when seated or standing.

To check yourself, just put your rig on your tripod and figure out where you like it. Then measure that height.

Patrick


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ur7x
professor emeritus


Reged: 01/08/12

Re: Pier Height Suggestions/tips [Re: Patrick]
      #5843896 - 05/06/13 04:11 PM

Lol... would you believe my belly button is pretty much 42" off of the ground. Just measured it.

My co-worker are all wondering, but none had the "guts" to ask.


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