GeorgeCarey
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Posts posted by GeorgeCarey
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This shows the balance tool in operation. The idea is to get the two red bars to hit the same spot.
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Where are you in the UK, Mike?
I am happy to give advice when you get it. The learning curve can be a bit steep.
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Hi Mike,
Did they have the mount running at the show? I went early on Friday and they were still setting it up.
Do not be too discouraged about the balancing issue. I am the lunatic who used the 'hang it from a wire' technique, mostly because I can't resist tinkering with things beyond the point that normal people would have stopped. As far as I know, nobody else has gone to such lengths.
Having said that, the DDM mounts are much fussier than the normal gears and worm type mount. As you will have seen at the show, the only thing that holds the scope in place and tracks the stars is a very strong magnetic field. If the scope is unbalanced then the currents rise and the software can get into a frazzle.
I have had my mount for five years and balance has not been a major issue. I did have a few mechanical problems but ASA paid for the mount to be shipped back to Austria and repairs were not charged for.
George
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I checked my settings - they are the same as yours.
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I think your settings are OK. I will check mine when I next switch on.
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The sequence I follow is:
Polar alignment:
Clear configuration
Start a 3 star model, one hemisphere only
Find the first star by hand. When it is found sync on it with CDC.
This tells Autoslew where you are pointing.
Start the new pointing model
Autoslew may ask about syncing the first star - I have done it already so just re centre the star perfectly.
Move to and re centre another 2 stars with approximately the same Dec.
Stop the pointing file and then calculate the polar error.
Centre a star due South with Dec about the same as my latitude (this is for a ddm60.)
Let Autoslew move the star away, and then re centre it with the mount adjustment screws.
Repeat this process until polar alignment is good.
Now the larger pointing model using Sequence:
Set up the parameters in Sequence.
Clear all old configurations.
Move to a star due south about 40 degrees above horizon.
Centre it and sync on it using CDC.
Tell Sequence to create the auto pointing file.
That is about it. If I have omitted an important step I hope someone will correct this.
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Are you in a fixed observatory? I am not sure what you mean by ' a larger initial align'.
When I last set my system up (in a fixed observatory) I spent a long time getting the polar alignment very precise.
This was by using the approved 3 star in one hemisphere method.
When I had the polar alignment better than 1 arc minute I was able to slew to any star (without a pointing model) and it would be quite close to the centre of the image.
Stars in the other hemisphere were a bit further from centre, but still on the image.
Then I checked Sequence to make sure I had the arcsec per pixel correct and the other parameters.
Then clear old configuration and run the autopoint.
George
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if you are using Sequence to do your autopointing files then CdC is not involved.
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Strange that your platesolves fail. My last pointing file had about 50 stars and each one was solved almost instantly. Perhaps Sequence has not got the correct parameters for your system? Have you inspected the images visually? Is there anything wrong with them?
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I think you may be making pointing models with two many stars. Because you are still getting to know your mount and ironing out difficulties, it may be better to stick to small pointing models to begin with. If you spend some time getting polar alignment very good, then pointing models are much easier. Try 5 stars in each hemisphere to begin with.
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Thanks for the information Astrograph. I see that you are at the Astronomy Show on Oct 2-3. I will pop in for a chat.
George (Satisfied DDM60 user).
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Thanks for the report Robert. There is a lot to think about!
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Good idea Mark.
In that case, my posts have been based on the theory that lateral balance is needed, but full radial balance is not necessary.
Obviously longitudinal balance is also required.
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Full radial balance IS necessary, and can be achieved by a single weight, somewhere near the focuser/camera.
This shows radial balance:
'Lateral' balance is illustrated looking sidelong at the telescope:
The red circle shows a possible position for the counterweight.
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If you take a photograph of your system, from the front of the tube looking down towards the mirror, it might make it easier to describe what you need to do.
Talk of axes, planes etc is confusing.
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The hanging on a wire method shows radial balance - that is why I came up with the idea.
It also shows lateral balance.
If you look along the length of the telescope tube then the wire should be exactly perpendicular to the telescope mounting plate if the radial balance is good.
If the wire is perpendicular to the plate no matter what direction you look, then balance is good in all planes.
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Hi Ian, have you seen this thread?
http://forum.astrosysteme.com/index.php?/topic/553-scope-balancing/
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Have you turned on data logging? This is a good way to see what the currents are doing when you get errors.
George
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It is also a good idea to check the clock in the PC. Is the offset in RA only or RA and DEC?
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Thanks Mark.
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Having taken my mount off the pier and replacing it I have to do a new polar alignment.
The manual still says use 4 stars, but after calculating the pointing file the top option for polar alignment says '3 stars'.
Which is it?
I am assuming that the star chosen for the polar alignment 'move' should be due South and at the same altitude as my latitude (52 degrees).
Is this still the best option?
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I have always assumed the value is in arc minutes. Some people say that anything less than 2 minutes is ok.
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Try telling the mount to ignore the limits when you start. Sometimes when you switch on, the mount can think it is near a limit and will refuse to move.
Balancing Newton on DDM60pro
in ASA DDM60/PRO
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Yes, it is part of Autoslew. I had a look for the user manual but ASA appear to have a new website layout and I could not locate the English version.