Can I point my EQ Mount to the North for observing?

[mbaddah (Mo)]

Just finished hooking up my eq5 and ed100 (following GEM guide in "Articles section", thanks Trevor!). It is currently in "home" position, i.e. mount and scope facing South.

Can I simply re-point my scope+mount in opposite direction, i.e.facing North, to view stars rising from East through North to West, or must I keep the mount in home position, and somehow re-orientate the scope when viewing in opposite direction?

Your help is greatly appreciated thankyou.

[Omaroo (Chris Malikoff)]

Hi Moh

With an equatorial mount, it's the right ascension axis (RA) of the mount that you align to point at the SCP. Once that's done, you can release both the RA and Declination clutches and swivel the scope to wherever you want. The mount itself is still pointing south at all times, so wherever you leave the scope pointed it will move (if the mount drive electronics are on) in right ascension to move with the stars. A lot of people find the movement of the scope around both the RA and Dec axis to be far from natural at first - so priactice by spotting something around the scope and get used to swivelling in these two axes to get there.

So - is your questionin relation to just moving the mount, or are you asking how you move around once you're polar aligned and then star aligned in software?

[mbaddah (Mo)]

Hi Chris

My question was related to both, i.e. does the eq mount have to be fixed in the direction of south to view stars in the north? Or is it ok to face the mount to the north?

i understand it'll take some practise to move around using RA/Dec coming from an Alt/Az mount

My view of the south is completely blocked by our house so can only view from North, and slightly west/east. Haven't got to polar aligning yet getting past the first hurdle has been scary

Thanks Chris,

Regards,
Mo.

Originally Posted by Omaroo

Hi Moh

With an equatorial mount, it's the right ascension axis (RA) of the mount that you align to point at the SCP. Once that's done, you can release both the RA and Declination clutches and swivel the scope to wherever you want. The mount itself is still pointing south at all times, so wherever you leave the scope pointed it will move (if the mount drive electronics are on) in right ascension to move with the stars. A lot of people find the movement of the scope around both the RA and Dec axis to be far from natural at first - so priactice by spotting something around the scope and get used to swivelling in these two axes to get there.

So - is your questionin relation to just moving the mount, or are you asking how you move around once you're polar aligned and then star aligned in software?

[Blue Skies (Jacquie)]

If you do what I think you're describe ie turn the mount to the north, then it wont work (some smart alec will come along and say yes it will just to confuse you but it will be awkward, its not what you are trying to achieve). You line the RA axis up with the SCP and leave it. You'll find the scope will twist around to the north on the two axes with no troubles, it will cover the whole sky, just like the dob did. Regardless as to whether you can actually see the SCP or not, it still has to be facing that way. Just try pushing it around without any motors working to start with (let the locks off and go loose) so you get an idea of how it moves.

[mbaddah (Mo)]

Thanks for the response

Do you know of a video of some sort clearly demonstrating how this can be done?

Originally Posted by Blue Skies

If you do what I think you're describe ie turn the mount to the north, then it wont work (some smart alec will come along and say yes it will just to confuse you but it will be awkward, its not what you are trying to achieve). You line the RA axis up with the SCP and leave it. You'll find the scope will twist around to the north on the two axes with no troubles, it will cover the whole sky, just like the dob did. Regardless as to whether you can actually see the SCP or not, it still has to be facing that way. Just try pushing it around without any motors working to start with (let the locks off and go loose) so you get an idea of how it moves.

[Omaroo (Chris Malikoff)]

Moh - here's a YouTube movie that shows the motions - but under motorised control rather than by hand slewing. At least it will show how GEMs move in both axes.

Also: Make sure your mount is balanced before you go slewing around, otherwise you might inadvertantly damage the gearing and/or clutches!!! There are two axes in which to balance your scope and mount.

1) First: Lock the Dec clutch and loosen the RA one. Tilt the scope in RA (around the central axis that points to the SCP) until the counterweight shaft is level to the ground. While holding it there, gently start to loosen your hold. Don't let go - just loosen. Does the mount want to tilt by itself towards either the scope or counterweight? If it wants to tilt back down towards the counterwight then loosen the counterweight lock screw on the shaft and gently nudge it UP the shaft towards the scope. Lock the counterwight screw and try again until you can let the thing go and it just sits there. Now if you nudge it in either direction it should move and slow down again quickly. If it now moves by itself towards the scope side, slide the weight DOWN the shaft away from the scope. All you are trying to do is balance it in the RA axis.

2) Secondly: Leave the scope with the counterweight shaft in the horizontal position again and lock the RA clutch to hold it - and lock the Dec clutch as well. It should now be balanced, so it wont strain the clutch or worm gear in RA. Now gently release (again, while holding the OTA) the Dec clutch. If the scope tilts towards the front it's sitting in the dovetail too far forward. Release both clutches and tilt the whole lot bolt upright. Loosen the dovetail lock holding the scope and slide the scope back a little and lock it again. Repeat from step (2) until it's balanced in that axis as well.

Now - watch this movie:

http://au.youtube.com/watch?v=uJNjvtpjQvk

Although it shows a scope slewing under motor control, it gives you an idea on how an equatorial mount moves about both the RA and Dec axes to point to anywhere in space - north, south, east, west or anywhere in between.

[mbaddah (Mo)]

Thanks Chris for the tips on balancing and the video

I can see it will definitely take some getting used to for a while

[cruiser (Brett)]

Hi Moh,

I recently got myself a HEQ5 mount and found the following site interesting in showing how an EQ mount moves.

http://www.themcdonalds.net/~themcdo...uatorial_Mount

Brett