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Equatorial platform leveling

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#1 N3p

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Posted 26 April 2019 - 12:07 AM

These days I think a lot about upgrading the size of my telescope.  I used a 8" Newtonian for almost 4 years now and I am still amazed, I am capable of finding some very faint targets and have great results with averted vision. But.. a 12" mirror would help me so much, I dream about that extra light gathering to reveal more of the DSOs.

 

But the more I think about the details of such project, the more I realize it's not just a matter of buying a 12", the tracking issue is bothering me quite a bit as I currently use a very effective GEM to track and sketch all the time.

 

With a 12" manual Dobson based Newtonian, the equatorial platform is mandatory and the Chinese melamine dobson base with tracking won't cut it for me even if the technology is amazing. My idea would be to get a manual 12" dob with a home made EQ platform, perhaps like the Explore Scientific 12" trust dobson that looks small enough to fit on the back seat of my Honda Civic once dismantled. It looks much smaller then the heavy Skywatcher Synscan base as well as the Orion goto heavy bases for their solid tubes.

 

My main problem is with the EQ platform, my observation spots, most of them,  the ground is uneven or with rocks, so I wonder if anyone invented a way to level the equatorial platform on uneven terrain. I can browse the Internet and look at a multitude of similar equatorial platform but none of them can be used on uneven ground, they are meant to be used on a cement slab, I don't have such luxurious terrain unfortunately. 

 

Anyone having the same issue and have ideas to install the EQplatform on uneven terrain?  An all terrain equatorial platform confused1.gif


Edited by N3p, 26 April 2019 - 12:08 AM.


#2 The Ardent

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Posted 26 April 2019 - 01:22 AM

I have an old EQ platform without leveling feet. I use small wood blocks for shims. My driveway slopes down a little.
I plan to make a couple of leveling feet out of 3/8" screws and knobs.

If you look at the current EQ platforms leveling feet are included. But all the pics show them on wood blocks like I use. http://www.equatoria...platforms.shtml
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#3 ngc7319_20

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Posted 26 April 2019 - 03:54 AM

I have a couple large 16 inch "stepping stones" that permanently stay in the lawn for the EQ platform.  And a collection of bricks, wood bits, and 1/8" thick rubber pads I use to level.  I take a picture of the set up to make it go faster next time.  I mounted a couple bubble levels on the stationary part of the platform -- sort of coarse and fine level indicators.

 

IMG_8272xss.jpg


Edited by ngc7319_20, 26 April 2019 - 04:14 AM.

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#4 petmic

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Posted 26 April 2019 - 04:25 AM

IMHO there is no need to level the EQ mount. All what is need to is to align the RA axis with celestial north using the RA and DEC adjustment screws. 



#5 N3p

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Posted 26 April 2019 - 10:04 AM

Ok you guys use shims mostly.



#6 Jon Isaacs

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Posted 26 April 2019 - 10:18 AM

IMHO there is no need to level the EQ mount. All what is need to is to align the RA axis with celestial north using the RA and DEC adjustment screws. 

This is an Equatorial platform, not a Gem. 

 

6287012-10 inch Dob on EQ platform.jpg
 
It's designed for a specific latitude and adjusting the level is the way the RA axis is aligned.  Mine has adjustment screws at the corners.

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#7 ngc7319_20

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Posted 26 April 2019 - 11:04 AM

Ok you guys use shims mostly.

Yup.  My observing spot is on a hill.  Also the design latitude of my platform is about 4 degrees off of my location.   So I end up needing about 4 inches of shim on the south end of the platform -- a brick works nicely.   I keep a bag of various bits of wood, rubber shims, etc., with the platform.  It's not a big deal -- just takes 2 minutes to level.

 

The north-south leveling is critical to get accurate tracking.  The east-west leveling doesn't matter so much.

 

The other critical adjustment is getting the north end of the platform pointing north.  I have a magnetic compass mounted on the platform which is accurate enough for most work.  There are also ways to use a 1x finder with Polaris.  Once you have it aligned and tracking well, you can make some marks on the pavement / pavers / or whatever to speed the alignment next time.

 

IMG_5612xs.jpg


Edited by ngc7319_20, 26 April 2019 - 11:19 AM.

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#8 decep

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Posted 26 April 2019 - 11:15 AM

IMHO there is no need to level the EQ mount. All what is need to is to align the RA axis with celestial north using the RA and DEC adjustment screws. 

With an EQ mount, you are not aligning the RA axis with celestial north, you are aligning the RA axis with the Earth's rotational axis.

 

If the ground is slightly unlevel, the errors in tracking will be minor--probably not enough to worry about for visual usage.  If you want to do less manual adjustment (or AP) your mount needs to be level.



#9 N3p

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Posted 26 April 2019 - 12:17 PM

Yup.  My observing spot is on a hill.  Also the design latitude of my platform is about 4 degrees off of my location.   So I end up needing about 4 inches of shim on the south end of the platform -- a brick works nicely.   I keep a bag of various bits of wood, rubber shims, etc., with the platform.  It's not a big deal -- just takes 2 minutes to level.

 

The north-south leveling is critical to get accurate tracking.  The east-west leveling doesn't matter so much.

 

The other critical adjustment is getting the north end of the platform pointing north.  I have a magnetic compass mounted on the platform which is accurate enough for most work.  There are also ways to use a 1x finder with Polaris.  Once you have it aligned and tracking well, you can make some marks on the pavement / pavers / or whatever to speed the alignment next time.

 

 

Ok 2 minutes is not too long. Nice compass and bubble level installation on yours I'll keep that picture if you want.

 

Personally I try to level and align the things the best I can, I alway adjust the level of my gem.. All these actions will keep the object in the center for longer, it's important for sketching I find. One small readjustment after +-10 minutes seems reasonable.



#10 Jon Isaacs

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Posted 26 April 2019 - 02:12 PM

Ok 2 minutes is not too long. Nice compass and bubble level installation on yours I'll keep that picture if you want.

 

Personally I try to level and align the things the best I can, I alway adjust the level of my gem.. All these actions will keep the object in the center for longer, it's important for sketching I find. One small readjustment after +-10 minutes seems reasonable.

 

A GEM need not be level in order to polar align it perfectly, the only requirement is the rate axis be aligned with the Earth's polar axis.

 

An EQ platform doesn't have adjustable axes so it must be done with shims and jacking screws.

 

Jon



#11 N3p

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Posted 26 April 2019 - 02:28 PM

A GEM need not be level in order to polar align it perfectly, the only requirement is the rate axis be aligned with the Earth's polar axis.

 

An EQ platform doesn't have adjustable axes so it must be done with shims and jacking screws.

 

Jon

Yes I agree.


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