EQ3 mount above 25 Latitude

Damienandwendy (Damien) · #1 31-07-2011, 02:19 PM

I have just got hold of a second hand Skywatcher 150x1000 Newtonian on an EQ3 mount. Then main problem is that if I try to set the mount to my latitude of 19 degrees south the counterweight hits the south leg of the tripod at approximately 25 degrees. Makes any attempt at polar alignment a little difficult.

I guess I can probably try some small diameter counterweights or may get a slight bend put into the counterweight bar. I have also read of people installing a short pier extension to help as well but these were aimed more at Vixen mounts that you can easily get pier extensions for.

Any ideas on a simple fix ?

cheers

Damien

bojan · #2 31-07-2011, 02:47 PM

Try to rotate the mount in tripod by 180 degrees, so that the south leg becomes north leg.

renormalised (Carl) · #3 31-07-2011, 02:50 PM

Get a shorter/longer weight bar.

Or see if the half pillar you can buy for the EQ6 mount will fit the EQ3 mount.

renormalised (Carl) · #4 31-07-2011, 02:50 PM

Quote:

Originally Posted by bojan

Try to rotate the mount in tripod by 180 degrees, so that the south leg becomes north leg.

Or that as well.

jenchris (Jennifer) · #5 31-07-2011, 03:14 PM

Saw a gap in the leg.
Use a weight with a higher density so it's not as big - lead is good - pester a tyre place for their lead weights off the car wheels.

Cast into an old can that will give you clearance and peel the can off after and drill the weight accordingly.

Damienandwendy (Damien) · #6 31-07-2011, 04:14 PM

Quote:

Originally Posted by bojan

Try to rotate the mount in tripod by 180 degrees, so that the south leg becomes north leg.

Unfortunately there is a fixed stop to allow slight adjustment in azimuth to assist with polar alignment that prevents rotating the mount head 180 degrees. Just pulled it head off to see if I could. Thanks anyway though.

By the looks of it, I can probably polar align the mount with the counterweights off then rotate in RA to where I intend to look ... predominantly south to southwest where the light pollution is the least .... and remember if I swing too far the other way that the tripod leg is there.

Failing that .... smaller / modified counterweights will be the next option.

cheers

Damien

asimov (John) · #7 31-07-2011, 04:20 PM

Yeah, you'll have to relocate the adjustment stop, or post 180 degrees as well in order to rotate the mount head. I'm only assuming an EQ3 setup is the same as an EQ5/EQ6 here though! I'm not certain it has this post on the tripod..

Damienandwendy (Damien) · #8 31-07-2011, 11:10 PM

I have just been tinkering out the back with the counterweights off and attempting some sort of polar alignment. I found that the what I was looking at was quite a bit lower than where the SCP should be.

Now I have made an assumption that the telescope should be parallel to the polar axis of the mount and if I place an inclinometer on the scope after the mount has been levelled, it should measure the same as the latitude marker on the mount.

Well I had to raise the latitude to just on 25 degrees to level the scope. So either the level bubble in the mount base is out or the latitude marker scale has moved.

Any thoughts ?

Damienandwendy (Damien) · #9 02-08-2011, 11:05 PM

After doing some more research, it appears that the latitude scales on these mounts are not known to be accurate and are just a rough guide to get you in the ballpark.

So tonight I went out and had another go at polar alignment. I set the Dec to 90 and RA so the counterweight was perpendicular hanging down. I used my binos to locate the 3 sort of bright stars in the centre of Octans that point to the SCP and aligned the scope/mount accordingly. I then looked through the scope and tweaked the latitude and azimuth adjusters on the mount till the centre of FOV was where I though the SCP should be. This was Ok but at x166 mag my targets were quickly drifting away from my RA axis. I made some slight adjustments that enabled the target to stay in the center of FOV for about 5 min, which I though OK for a first go at it.

cheers

Damien

Damienandwendy (Damien) · #10 05-08-2011, 07:50 PM

I posted the issues I was having in my local Townsville Astronomy Group forums and got some good advice. The following link is a guide to polar alignment that can be achieved in daylight hours and is good enough to allow tracking for 10 min leaving the target in the center 50% FOV.
http://www.astroholic.com/showthread.php?t=595
Thanks to Vinnie.

cheers

Damien

Damienandwendy (Damien) · #11 11-08-2011, 08:23 PM

I setup the scope at a midweek star party only to find the slight change in setup, ie where the tripod was sitting, meant that the counterweights hit the tripod leg when polar aligned instead of the approximately 2mm gap I was able to get in the backyard.

I have no choice but to either manufacture a small pillar extension or modify my counterweights to suit. A Vixen pillar at $200 is not really an option.

It's quite annoying that something marketed in this country cannot be used correctly north of Rockhampton without being heavily modified.

Hopefully I can get something sorted for less than $50.

Or maybe I should just post 4 or 5 different threads about my new scope and when it will and won't be delivered.

Damien

Grimmeister (Anthony) · #12 23-08-2011, 08:57 AM

Hi Damien,

I live in Brisbane and have the EQ3 mount operating without issue and the balance bar misses the tripod leg by about 2-3 CM so I would have thought when correctly aligned you should have a little wiggle room left.

If not a suggestion that may work for you, I noticed on my tripod (has Aluminium legs) that directly opposite the spike used for azimuth adjustments there is a hole on the under side. Would it be possible to cut off the spike and then in the 180' position drill a hole and but a similare sized threaded bolt through? this way you could reverse the mount on the tripod the 180' required.

Let me know if you would like a picture of what I am trying to explain.

And yes you are right it does seem silly that a mount made these days would be so limited for a location neaer the equator.

Cheers

Anthony

Grimmeister (Anthony) · #13 23-08-2011, 09:01 AM

Hi Damian,

Please disregard, I just saw your other post and the extension pier, nice job and looks good too (maybe just needs a little black paint and will look like it was part of the setup)

Cheers

Anthony

Damienandwendy (Damien) · #14 23-08-2011, 05:46 PM

Hi Anthony,

I had thought of something very similar to what you were suggesting, but didn't want to modify the mount too much just in case I screwed it. So I went for the pillar to pretty much keep the tripod/mount in original condition.
I have been thinking about painting it, just need some motivation .... and the appropriate paint !

cheers and thanks

Damien