Help with German Equatorial Scope Alignment

TheFacelessMen (Rob) · #1 27-09-2010, 04:49 PM

Hi All

,

Apologies, I placed this in another folder on the forum and moved it to here.

I have been a telescope user on and off over the years starting out with a cheap but nice quality small Vixen refractor on a wooden tripod with manual controls and later using a couple of smaller Meade and Celestron SCT's on the fork mounts

Based on a lot of positive reviews I have recently taken the plunge to upgrade to a takahashi mewlon 250 and takahashi em400. As this did not come with a GOTO I decided to purchase the SkyFi wirless controller and SkyVoyager software to provide goto control using my Iphone.

Apart from spending too much money

, I didnt think about or realise the setup differences between the fork mounts and german equatorial mounts

so now am in a little bit of a bind about how to properly setup and align both the mount and optical tube

I found a good article on here about setting up a german equatorial mount which has help a bit for setting up the mount but I still cant seem to get correct alignment at the eyepiece.

1. Is there something more/different that I need to be doing to better align the mount??

2. Should I be orienting the Optical Tube in any special position on the mount ??? The takahashi does not seem to have any special home position.

Any advice to help me would be greatly appreciated

ballaratdragons (Ken) · #2 27-09-2010, 05:11 PM

Hi Rob.
I'm trying to work out what you are actually asking.

Are you asking How to Polar align the Mount?

or

How to attach the Telescope onto the Mount correctly?

TheFacelessMen (Rob) · #3 27-09-2010, 05:32 PM

Quote:

Originally Posted by ballaratdragons

Hi Rob.
I'm trying to work out what you are actually asking.

Are you asking How to Polar align the Mount?

or

How to attach the Telescope onto the Mount correctly?

Hi Ken,

As mentioned, all my prior scopes ( 3

) were either manual alt/az (no drives) or meade/celestron goto fork mounts.

So I have had no prior experience setting up and aligning a german equatorial mount based scope

.

The post in the beginners section explains how to do this which I have followed but I think either my mount polar alignement is still off or my alignment of the Tube on the mount is not correct or off.

Whatever it is when I try to do a goto the scope does not put the correct object in the eyepiece view.

Assuming that the mount itself is correctly polar aligned and it is something else that I am not doing correctly or missing after I polar align the mount where could the problem be?? ( always accepting possiblity of the user

)

Should I be orienting the OTA in a particular fashion?? or aligning the OTA in a particular way??

thnx

DavidU (Dave) · #4 27-09-2010, 05:45 PM

Here is some good info.
http://www.astronomyforum.net/austra...emisphere.html
Did you get this mount from overseas?

ballaratdragons (Ken) · #5 27-09-2010, 05:51 PM

hmmm . . sounds like some common problems people have:

Daylight Savings settings

Lat/Long

wrong hemisphere settings

etc

Have a read through the link Dave provided above

But most of all, don't feel beaten.
They are all common mistakes when people first start with EQ's.

AS for mounting the scope on the mount. There's nothing that can go wrong here. The scope mounts on top usually by a dovetail rail. Hard to get this part wrong.

TheFacelessMen (Rob) · #6 27-09-2010, 06:16 PM

Quote:

Originally Posted by DavidU

Here is some good info.
http://www.astronomyforum.net/austra...emisphere.html
Did you get this mount from overseas?

Quote:

Originally Posted by ballaratdragons

hmmm . . sounds like some common problems people have:

Daylight Savings settings

Lat/Long

wrong hemisphere settings

etc

Have a read through the link Dave provided above

But most of all, don't feel beaten.
They are all common mistakes when people first start with EQ's.

AS for mounting the scope on the mount. There's nothing that can go wrong here. The scope mounts on top usually by a dovetail rail. Hard to get this part wrong.

Hi Dave and Ken,

Thanks for the article and advice. I am doing something similar with the mount & tripod level and ajustment at the moment.

I have a template made (measured with a proper protractor) for the angle of the mount and use a small level to make the tripod is level. My mount is oriented south based on instructions from the article in the beginners section of IIS.

I then load and balance my OTA with a final check after that to make sure I have not moved the mount and tripod out of position.

My software uses the internal GPS locator for location in the iphone 3GS which I have checked is ok and the mount is pre-configured for Southern Hemisphere. (is was also purchsed from the Australian supplier).

This is what makes me think that is is something I am doing with the final Optical Tube positioning or alignment.

Thnx

noswonky (Peter) · #7 27-09-2010, 06:31 PM

After the steps you mentioned, are you doing a two or three star alignment?
You have to somehow tell the software, which way the scope it pointing.

M54 (Molly) · #8 27-09-2010, 07:26 PM

Hi Rob,
This is probably a stupid question but I assume you have the user manuals?

If not here is a link to the relevant ones...

http://www.takahashiamerica.com/manu...wlon%20250.pdf

http://www.takahashiamerica.com/manuals/EM-400.pdf

TheFacelessMen (Rob) · #9 27-09-2010, 07:49 PM

Hi Peter,

SkyVoyager for the Iphone only seems to have a sync/align option.

As further clarification to everyone this is my process:

Setup tripod and make sure it is level using bubble level
Fit mount head and adjust tripod to true south
Adjust inclination of mount head to suite location using protractor template
Fit mount and adjust/check for any movement in pointing south or inclination
Load OTA onto mount and lock down
Balance OTA in both Dec and RA
Return OTA to position where OTA is on "top" and counterweight bar is back to vertical
Connect SkyFi, IPhone and Power
Power mount
Manualy slew to nearest bright star
Sync software to that star

SkyVoyager reports sync.

It keeps the star in eyepiece but as soon as I issue a GOTO the scope slews and there is now star/object in view.

Scope seems to be pointing in the general area but is way off

It seems to be too far out than what a small alignement error would allow for.

Please tell me if I am missing anything really simple or should be doing something else.

Quote:

Originally Posted by noswonky

After the steps you mentioned, are you doing a two or three star alignment?
You have to somehow tell the software, which way the scope it pointing.

TheFacelessMen (Rob) · #10 27-09-2010, 07:54 PM

Hi Molly,

No question is stupid

I am sure it is something silly and basic I am doing wrong.

To answer your question Yes I have the latest manuals that shipped with all the gear and they have a nice Japanese to english translation

.

[
QUOTE=M54;639452]Hi Rob,
This is probably a stupid question but I assume you have the user manuals?

If not here is a link to the relevant ones...

http://www.takahashiamerica.com/manu...wlon%20250.pdf

http://www.takahashiamerica.com/manuals/EM-400.pdf

[/QUOTE]

DavidU (Dave) · #11 27-09-2010, 08:13 PM

Peter, what is your idea of true south? I also see that the manual for the EM400 only has northern hemisphere alignment.

DavidU (Dave) · #12 27-09-2010, 08:19 PM

Pete, down load Magvar,it computes and displays magnetic variation for anywhere in the world.
http://www.pangolin.co.nz/free_stuff.php

TheFacelessMen (Rob) · #13 27-09-2010, 08:21 PM

Hi Dave,

It seems that my EM400 is a different updated version. It is a EM400 Temma 2 - SH and according to the manual (and also the controls) is presetup for Southern Hemisphere. Also according to my manual I can over ride this if I want to to use in Northern Hemisphere ( not that I will be doing that

)

The online manuals that Molly pointed to seems to be for an older or different version.

I also found another thread on here tonight where one of the other IIS members mentions the same thing.

Quote:

Originally Posted by DavidU

Peter, what is your idea of true south? I also see that the manual for the EM400 only has northern hemisphere alignment.

Screwdriverone (Chris) · #14 27-09-2010, 10:21 PM

Hi Rob,

Not sure if you have done this, but you mention everything else aligned except checking if you are ACTUALLY pointed at the SCP.

I wrote a guide on this and how to recognise the stars of sigma octanis in the articles section which could help you understand and recognise if when you have the scope "parked" at the south position you are actually close to the SCP. Here it is. You will just need to spin everything 180 degrees from the pics as I did this when everything was up the other way and Achernar was in the south west, not the south east like it is now. But the method still works.

One reason I wrote it is because I checked and checked over and over but when I pointed my scope correctly at the SCP, I found my tripod was not pointed exactly at it AND, worse still, my latitude scale was WOEFULLY incorrect by about 15 degrees!

Take a look and see if you can recognise the SCP through the finder or even the main scope with the widest eyepiece you have, once you have the scope right, then look at the other things.

When you mention you point the scope to the bright star and then "sync" the program, I assume this is just about the same thing as when i do my 1 star alignment on my HEQ5 (or use EQMOD with Stellarium).

What I have noticed is that when I do that (and my scope IS dead on the SCP) through the polar scope and the finder etc) is that the goto on my mount is not as accurately synced as it can be and the results I get sound A LOT like yours, in the general area, but significantly off.

I use the 3 star alignment as a preference as the results are 10 times better when I do, something which I think you might not be able to do with what you have.

So therefore, see if you can determine that the mount is properly aligned and pointed at the SCP, THEN try your Iphone app and see if it improves. With only one star to align on, there is nothing to fine tune the system compared to the accuracy of using 2 or even 3 stars to lock you in.

Good luck with it, sounds like a cool setup, hope you get it sorted.

Cheers

Chris

TheFacelessMen (Rob) · #15 28-09-2010, 05:02 PM

Hi Chris,

As far as I can tell I am; but being 100% sure with my eyesight

on that target can be a problem.

You are correct with the sync function. Unfortunately SkyVoyager does not have a multi-star sync option ( at least for the Tak driver).

Another IIS user has also been very helpful in providing step by step advice and a number of suggestions and we think we may have nailed it down to:

1. Some critical point not in alignement ie, maybe not properly aligned on SCP in polar scope or some other hardware out.

2. Potential problem with slewing in software or mount.

Which also seems to agree with your recommendation as well.

Thanks for the advice and comments

I will be paying close attention to these in the next few nights to try and see where the problem is.

gregbradley · #16 28-09-2010, 11:55 PM

I always used the drift alignment method to align the mount.

The reasons for this are:

1. Not all sites can see the south celestial pole.
2. Sigma Octans and nearby stars are very nondescript/not bright and in a suburban area perhaps invisible with light pollution.

Some master this skill and I'd say it is worthwhile to be able to setup a mount using the polar alignment scope which with a Tak is supposed to be very good.

Drift alignment though measures your mounts drift which ultimately is what you want reduced for autoguiding when doing long exposures.

It doesn't have to take too long - maybe an hour.

There are good writeups about how to do it. Its a good idea to persevere and learn it as it will help you long term and without it it will be hard to get good images.

Greg.

TheFacelessMen (Rob) · #17 29-09-2010, 12:51 AM

Hi Greg,

It is obviously going to take me a little practice with setting up and aligning a GEM style mount. My fork and alt/az mounts were basically "point and shoot".

Hopefully with some clear skies I will be trying out some of the suggestions that have been PM'd and posted.

I am a little surprised that given the number of IIS members seemingly with GEM mounts that only one or two members could actually provide me with step-by-step help to how I should setup my GEM mount and OTA in terms of physical alignments (prior to software sync's).

Maybe it is something so basic to long term GEM mount users that it is overlooked

or is it the secret sauce

Cheers

Quote:

Originally Posted by gregbradley

I always used the drift alignment method to align the mount.

The reasons for this are:

1. Not all sites can see the south celestial pole.
2. Sigma Octans and nearby stars are very nondescript/not bright and in a suburban area perhaps invisible with light pollution.

Some master this skill and I'd say it is worthwhile to be able to setup a mount using the polar alignment scope which with a Tak is supposed to be very good.

Drift alignment though measures your mounts drift which ultimately is what you want reduced for autoguiding when doing long exposures.

It doesn't have to take too long - maybe an hour.

There are good writeups about how to do it. Its a good idea to persevere and learn it as it will help you long term and without it it will be hard to get good images.

Greg.

ballaratdragons (Ken) · #18 29-09-2010, 01:05 AM

Rob,

if it is polar alignment you need help with, you can try my method.

Works for me.

http://www.iceinspace.com.au/forum/s...ad.php?t=24879

As for your settings after that, I can't help. I know nothing about your type of mount. I freaked when you said you only align (sync) with one star!

I have an EQ6 where 1 star alignment isn't very accurate so I do 3 star alignments.