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How high should the pier in my obsy be?


Mikyg

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How high should a telescope pier be in a roll off roof obsy? I read somewhere that it should be the same height as my obsy wall but I had in my head that if i worked out the distance from the bottom of the mount on my neq6 to the center of my OTA then subtracted that from the height of the walls then that should be the height that my pier should be??

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It will depend on the the type of scope used, a refractor you look through the end closest to the ground, a reflector is the other way round, then there's the height of the walls and ceiling clearance, with the scope leveled and the weights sideways , the roof needs to clear these when it closes,,,so really there's no fix height depends on what you are using.....

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Im using the 250pds which is a 10" reflector but i'm building the obsy myself so i can build it with plenty of roof clearance. If the mount is set level with weights out to the side and scope facing flat to the horizon im thinking the scope should be able to see the horizon over the walls when levelled with the roof off??

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Why would you want to look that low down? Most observing must start at 20 deg. Imaging probably higher so set the height to the lowest you will want your scope to go. The higher your walls can be the more protection you will get.

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i had the same problem when i built my obsy, what i did was to use the mount inside the obsy and then changing the height of it to suit then put the pier in at the height i needed. alittle tricky but it worked for me.

there`s a bit about my pier build on my website.

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My pier is 85cm tall. Add on to about another 30cm for the mount and you get an idea of the height.

I wouldn't build the pier too high as you will have to lift the mount onto it and the scope onto the combined pier + mount height.

There are no hard and fast rules: that "A" must equal "B" or what you "can" or can't do. It's all about making the observatory as usable for you as possible.

For a visual observer, I'd suggest taking some measurements of what is comfortable  for you. If you already have a tripod mounted telescope, then take measurements off that. What is the maximum eyepiece height and what pose will you adopt to see through that? Similarly, how low down in the sky will you be pointing - are there obstructions, houses, etc. that mean you can't see below X° - and how do you plan to observe (sitting, standing, having a box to stand on) at those extremes. After that, work backwards to find the pivot point of your OTA(that will be independent of the angle the OTA is at to observe any particular object) , then further back to the height of your mount and that should give you the height of your pier.

The minimum viewing angle will then determine how high to build your walls and you will design the roof + trusses to allow it to clear your parked 'scope when it rolls off.

When you determine the height of your pier, don't forget to allow for the height of any false floor you may be planning.

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Imaging only, or visual? In imaging you don't need to be using an eyepiece so you can make it low. Our robotic shed has piers which just keep the cameras off the ground on the zenith.

How high you want the walls to be relative to the scope depends on the quality of your sky at low elevations and the obstructedness or otherwise of your horizons. Here we can and do image down to about 10 degrees where the horizon allows. (It is best to shoot red or Ha at these low angles and isn't ideal, but it can be a lot better than nothing.) If your sky is not good below a certain elevation then I would not bother to let it see over the walls in order to reach these poor regions. You'd be better off with the increased wind and LP protection of a higher wall.

Most of the proprietory UK roll off sheds roll the roof only. Because I wanted access to the low horizon in the east and south, though, I made ours with rolling roof and sides plus a drop down flap on the south east side. The owners who designed and built the robotic shed did likewise, with a nifty self opening and closing flap which still makes me chuckle with delight when I see it working! If you do go for the 'roof and sides' option it is easy to build. We have one with a steel frame and two with wooden ones. By the way, another space saver for imagers is the protruding 'computer pod' which makes for a much smaller footprint.

Here the roof-and-sides roll over the warm room;

ROLLING%203-M.jpg

And here's a smaller one not yet fully clad in the picture.

DOOR%203-M.jpg

Olly

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So to get the height of your pier if its for viewing, place it on it tripod in the garden point it at the zenith, measure the distance from the EP to the ground, the EP would need to be at eye height around 5' the base of your reflector will be around 12" of the ground, measure the distance from the dovetail the the rear of the scope, add the 12" and thats the comfortable height for viewing when sat on a pier, it doesn't need a tall Obby, but if you make the Obby to suit this height it will be quite low and will lead to back  pains due to being bent  over all the time when the roof is closed, a Obby with the height  so you can stand up will need folding down walls so the scope can view even at 45 degrees, the other option is a highing pier and some steps to stand on, this is not ideal as its dark and falling of them won't be healthy.

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Another common approach is to have a folding flap at the southern end of the observatory to allow horizon views.  Below is a pic from my build showing the pier & mount with the lower wall.

post-5202-0-78606400-1400055734_thumb.jp

But it all depends on your own local circumstances on what kind of wall structure you go for.  I preferred the higher walls because it often gets windy around these parts and wanted to the protection.

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I was thinking of building an imaging-only micro observatory with one of these:

http://www.simplygardenbuildings.co.uk/suncast-bms4900-kensington-7-glidetop-shed-39593-2567-p.asp

I needed to figure out the correct pier height to ensure enough of a view, plus no collisions and so that the roof could close.  I wrote this up:

http://www.blackwaterskies.co.uk/2013/12/observatory-planning-and-german.html

It may also be some help with planning a visual observatory, but clearly you'd need to factor in the additional space needed for the observer.  (I haven't gone ahead due to a lack of time, plus an ongoing spate of shed break-ins in the immediate area is making me question whether I want to risk it).

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I was thinking of building an imaging-only micro observatory with one of these:

http://www.simplygardenbuildings.co.uk/suncast-bms4900-kensington-7-glidetop-shed-39593-2567-p.asp

I needed to figure out the correct pier height to ensure enough of a view, plus no collisions and so that the roof could close.  I wrote this up:

http://www.blackwaterskies.co.uk/2013/12/observatory-planning-and-german.html

It may also be some help with planning a visual observatory, but clearly you'd need to factor in the additional space needed for the observer.  (I haven't gone ahead due to a lack of time, plus an ongoing spate of shed break-ins in the immediate area is making me question whether I want to risk it).

While that has much of what you need it really is so easy to knock up a ply-clad wooden framed structure that I wonder if modding somethng designed for another job is really worth it? The woodyard will cut your ply panels to size and you don't need real joints for the frame. The ply itelf will join them. My woodwork teacher would have chuntered but the ones I've made like that have all been fine, as has the large 4Mx3M robotic shed.

Olly

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The simple answer is as high as can whilst still being able to close it with the scope on (or the largest scope you are likely to own I should say).

This might mean a bit of jiggery pokery when parking the scope. With my 12" scope in place this means turning the scope to its lowest position, removing the counter weights and retracting the counterweight bar. Then the roof closes, just.

Scope in the 'parked' position.

Dscf6729_1024_zps5eb8f61b.jpg

The advantage of this is that I can easily clear the walls and image horizon skimming objects (of which there a lot in Sagitarius).

If you don't have a decent southern horizon to exploit then you probably don't need to go this high. The other downside is that the eyepiece end of a Newt could be 10 feet off the ground. Not a problem for imagining but clearly not good for visual.

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I am the one who designed the robotic at Olly's, including the concept of low piers. Having low piers removes so much of the hassles of building and the observatory comes out as a really neat little package. I really recommend it. The pier is 40 cm high and very stable with 10 mm thick steel plates and 5 mm thick riser. For size, that's a 10Micron GM2000HPS on it - a rather large mount.

/per

Rig2.jpg

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I am the one who designed the robotic at Olly's, including the concept of low piers. Having low piers removes so much of the hassles of building and the observatory comes out as a really neat little package. I really recommend it. The pier is 40 cm high and very stable with 10 mm thick steel plates and 5 mm thick riser. For size, that's a 10Micron GM2000HPS on it - a rather large mount.

/per

Rig2.jpg

Wow thats a tiny pier, thanks everybody for your help.

I am building the obsy for my old man and he wants to be able to control it all from his conservatory in the warnth so i have to hook up camera's on the focusser so he can see the image from a large monitor in his warm room but i will be using it for imaging.

I suppose it would be easier to just build my walls first then work it all out later. After some very good advice on here ive decided to put concrete pillars in each corner of my obsy floor and lay the wooden floor joice on them instead of having a full concrete base with pier built in. That way i can dig a one meter square hole and fill it with concrete for my pier later

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While that has much of what you need it really is so easy to knock up a ply-clad wooden framed structure that I wonder if modding somethng designed for another job is really worth it? The woodyard will cut your ply panels to size and you don't need real joints for the frame. The ply itelf will join them. My woodwork teacher would have chuntered but the ones I've made like that have all been fine, as has the large 4Mx3M robotic shed.

Olly

Well yes that is an option.

-  On the plus sidethe modifications to the mini-shed would be absolutely minimal : Cut a hole for the pier, maybe some kind of ground anchoring for security,perhaps a bit of extra waterproofing around the roof and door and a more sturdy locking mechanism.  I could cope with all that and be 100% sure it would work from the get-go.

- I have looked at modifying a full sized shed and ruled it out because it would require a lot more concrete, a lot of work to make a sliding roof, etc.  The cost of shed and materials would be a lot higher than the plastic option above, plus woodwork is not a strength (to put it mildly!)  I wouldn't be able to get any help with the lifting and shifting, which would be a major issue for the roof if nothing else. The space isn't needed for imaging so micro was definitely an attractive option.

- A ply self-build is another route to go down I guess, but I'd have to look at the cost of materials (which are not cheap in the UK for whatever reason).  My main worries would be:

- The need for a full concrete base or a wooden base on pads.  The plastic shed has its own base so could probably get away with just the pier foundation and maybe some small pads.  Building on clay here so it is like a lagoon most of the winter and hard as concrete by summer.

- Waterproofing - I have an old shed and a wooden kid's play house which have basically disintegrated over the past ten years due to the wet weather.  I don't have enough hours in the week to spend on fixing roofing felt, repainting with wood preserver, etc. so I guess it would be about five years before a ply construction might become a problem.

- Conversely there is some plastic kid's play equipment which is made from the same stuff as the shed above.  The neighbours got it for their kids in the mid 90's, passed it on to us and I handed it on to the neighbour on the other side for his grand-daughter.  Apart from a bit of colour-fade due to the sun, it is still as good as new (not to mention the best part of 20 years being tested to destruction by three sets of kids).  Seems like my kind of lazy-man's solution.

- Overall time to build.  I'm always impressed by the multi-month build extravaganzas that get documented on here, but I do not have that kind of free time available to me.  Something that I can unbox, modify and plonk down in a working state is a real must.  Building the pier can't really be short-circuited by everything else can be.

- Security is the big worry of course.  We're not exactly in a crime hot-spot round here, but casual break-ins to garden sheds seem to be the in thing this year.  Last year someone literally stole my garden gate of its hinges in the middle of the day.  Still giving some thought to the security issue, but really I want to be able to take advantage of the limited clear nights we get as I can't set up and break down during the working week, whereas sliding off a roof and firing up the laptop would be easy.

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This thread brings up a lot of very interesting points again :)  We need these points refreshing every now and then as they tend to get swamped in all the info in a full build thread.  Particularly mine :D  I like the look of my own words like I like the sound of my own voice :D

It has got me thinking again about my second "observatory" - a mini widefield imaging rig :D  Like just how low it could be.  The limiting factor would be the height of the fence posts I think and that of our neighbour's electric fence.

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Well yes that is an option.

- Security is the big worry of course.  We're not exactly in a crime hot-spot round here, but casual break-ins to garden sheds seem to be the in thing this year.  Last year someone literally stole my garden gate of its hinges in the middle of the day.  

I saw someone taking my gate once but I didn't say anything because I thought they might take a fence.

Sorry...

:grin: lly

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My main concerns when i built my Obby were, it has to be water tight, with no leaks which it is, and it won't get blown away which it can't, security isn't high on the list as its secluded and does have a large padlock.......

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It has got me thinking again about my second "observatory" - a mini widefield imaging rig :D  Like just how low it could be.  The limiting factor would be the height of the fence posts I think and that of our neighbour's electric fence.

Gina- you've probably seen this before but my outside widefield rig is deliberately low to keep the Newtonian working height low. I could use refractors on here but would be kneeling to get focus! It's never intended to use this rig for visual though it would be entirely possible with the Newts.

DSCF7947_1024_zps6d0bd30c.jpg

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