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Accurately setting the “Home” or “Park” position on a EQ5

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Just sharing a good link I use to set the home position on an EQ5 mount.

Edit: because I've seen many older blogs get lost... I shall replicate the content here.
All credits to Paul

Update 18 Jun 2011:

Since I originally prepared this article I’ve found that the steps set out th Starting from a known position section aren’t necessary. When the mount is powered on, regardless of whether you choose to start from parked position or not, and irrespective of what position the axes are in, the positions of AX1 and AX2 shown in UTILITY → SHOW POSITION will be the same. I’ve therefore removed the steps that are no longer required

It’s been quite a while since my last posting. In the intervening period I finally got round to acquiring a decent mount, the SkyWatcher EQ5 Pro. The only trouble is the weather’s not been too good and it’s way past 10pm before it gets dark enough for observing!

One element of setting up an equatorial mount is the establishment of the “Home” position. This is where the mount is “parked” at the end of a session. It is sometimes described as “weights down, scope up” and is often the position displayed in adverts. There’s an excellent video tutorial on YouTube accessible via www.astronomyshed.co.uk/ (“Complete Setup From A to Z Part 1”) which shows how to establish this position using an HEQ6 mount.

In essence, the procedure uses a spirit level to “level” an axis then rotate the axis by 90o so that it is then perpendicular. When both the RA and DEC axes have been set this way, the mount is in the correct Home position.

As owners of Skywatcher EQ5 mounts have long accepted, the setting circles leave a lot to be desired, and while it’s possible to use the technique in the tutorial on an EQ5, the inaccuracy of the setting circles means it’s a bit of a hit and miss affair.

The following procedure builds on the technique, using the Show Position function of the SynScan controller to accurately determine when an axis has rotated through 90o. Though described for an EQ5 mount, this procedure can be used with any equatorial mount with SynScan, whether factory-fitted or upgraded.

On the EQ5 tripod, one leg is marked N. This is the leg which is pointed North. For the purpose of this procedure this will be regarded as the front of the mount.

It is assumed that the user is familiar with the operation of the SynScan controller and its menus. Navigation to a sub-menu will be described thus:


( Starting from a known position section removed)

Setting the RA axis

Stand behind the mount, release the RA clutch and rotate the RA axis until the weight bar is horizontal and to the left. Use a spirit level to check then lock the RA clutch.
Switch ON
Step through the setup procedure. Note: Setting date/time/location correctly is not required at this, or any other stage of the process, nor is 1,2 or 3-star alignment.
Show the position of the axes. UTILITY → SHOW POSITION
Use the scroll keys to change the display so that the axis positions are shown in degrees, minutes, seconds:
AX1=+090o 00′ 00”

AX2=+000o 00′ 00”

(AX1 is the DEC axis, AX2 is the RA axis)

Set a fairly high slew rate (RATE 8 for example) then use the RA directional key to slew the mount until AX2 is close to reading 90o. Select a slower rate and carefully slew until the display reads
AX1=+090o 00′ 00”

AX2=+090o 00′ 00”

Using a fine marker and straight edge, make a mark to enable you to manually return the RA axis to its parked position.

Setting the DEC Axis

If you have one, fit a dovetail bar to the puck. This will provide a straight edge to rest the spirit level on.
Release the DEC clutch and rotate the DEC axis until the dovetail is horizontal, using the spirit level to check.
Again, start off with a high slew rate and rotate the DEC axis until the display indicates the AX1 axis is 90 degrees different to what it was. If your preference is to have the DEC motor to the left, then the display should read
AX1=+180o 00′ 00”

AX2=+090o 00′ 00”

If, however, you prefer to have the DEC motor on the right, the display will read

AX1=+000o 00′ 00”

AX2=+090o 00′ 00”

Using the marker and straight edge make a mark so the DEC axis can be returned to this position manually
Switch OFF
Switch back on again and step through setup.
Choose UTILITY → PARK SCOPE then switch off when prompted
The mount now has its axes accurately positioned and parked.
Kstars Mac osx
Odroid C4 / WO Redcat51 / CEM25p / ZWO533MC / QHY5L-II-M (OAG)
The following user(s) said Thank You: Richard Roth
Last edit: 4 years 1 month ago by Gonzothegreat.
5 years 5 months ago #18753

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As a fresh owner of an EQ5, I was looking with interest for such a guide and I was very happy when I found it.
I have one question, please: after performing the procedure and parking the scope, when I turned it on again, I wanted to see which values are shown for AX1 and AX2 position.
So the displayed values were AX1 = +090 and AX2 = +000, despite that at the end of the procedure I had AX1 = 180 and AX2 = 090.
Is that normal, or I did something wrong?

Thanks in advance for your support.
3 years 2 weeks ago #47952

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Hello, could it be due to the "DEC motor to the left/right"?
I have an heq5-pro so that DEC motor part does not apply for me. Sorry I don't have the answer to your question.
Kstars Mac osx
Odroid C4 / WO Redcat51 / CEM25p / ZWO533MC / QHY5L-II-M (OAG)
3 years 1 week ago #48089

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