Polar alignment with Astrotortilla - SERIOUSLY screwy!

[Demonperformer]

Despite the polarscope webcam not having arrived yet, I decided last night was too good an opportunity to miss, so I duly set up and had some 'fun' (in the sense of "sometimes I've had all the fun I can stand").

Tripod set at a reasonable height of about 1m, and looking through the polarscope. Maybe I was not close enough to the pole, maybe the led was far to bright, but one way or the other, there was no sign of Polaris. Not going to worry too much about this until the webcam arrives. If I still can see nothing when I know Polaris is in the field, that will be time enough. But, in case anyone reading this has found the answer:

Is there/what is the method of reducing the brightness of the led in the syntrek (not synscan) version of the mount?

But onto our main topic for this thread. I used the main scope again to put Polaris roughly central while it was 'parked' and then headed for the meridian. Took a couple of goes to get to the selected star in CdC, but I was quite impressed with how well it did the job. Selected the 'Polar align' option and pressed the 'meridian/azimuth' option. It said I was a couple of degrees too far west. So I moved the scope '3 turns' east (the plan was to record how things changed with how many turns of the lock-knobs - if I can find this correlation, it should vastly speed up the exercise in future). This time it said I had reduced the error by nearly half, so I gave it another '3 turns' plus a tiny bit extra. I was now just over a degree too far east. So I moved it back 2 turns, and now I was no less than 21 degrees too far east!

This set the tone for the next two hours. The results AT gave me seemed to bear no relation to what it had said previously and what I had done in the meantime.

As an aside, I did spend a bit of time finding objects with AT, and encountered another problem. Anything from 180 degrees S through W worked fine. When I tried to find an object to the east of the meridian, it duly did a meridian flip, but having slewed to 145 Azimuth, it stopped (a good 20 degrees east of the object). When I called up the EQMOD screen, it was flashing "Meridian Limit" at me. I simply do not believe that it is impossible to view an object within 35 degrees of S, and I am sure it is me doing something stupid again, but this is not a problem I have seen anything about. So my second question is:

What are these meridian limits and can I/how do I get rid of them?

Anyway, back to polar alignment with Astrotortilla. Having spent over two hours fiddling around with the problem, I decided enough was enough and I was going to pack up. Then I had an idea. One more go at getting the azimuth error, but I would not touch the scope/mount between attempts. I did three 'find azimuth error' procedures, back to back. I have attached the log of this exercise and also screen prints of the AT screen after each one. As you can see, considering that the error should be identical as nothing was touched, the results are SERIOUSLY screwy. So my third and final question is:

Can any AT experts out there, with the aid of these results, offer any kind of explanation of what I am doing that I shouldn't be doing/not doing that I should be doing?

I do hope things get better than this ...

Thanks.

PA 1-3.txt

[Demonperformer]

Chris,

Thanks for the email, I will respond here so others can get the benefit if they encounter similar problems.

Polar scope alignment:

No, I did not realise that the polar scope had a moveable focus. Tried moving things around, but nothing seemed to move 'in situ'. However, I have now tried playing indoors again, and found that the focusser, although initially a little stiff, now moves quite freely. It was indeed fully screwed in (which I guess is not too close to the focus point!) so I will try that when I get out again. That, as you say, may solve the problem.

Thanks also for the link to fitting a 'dimmer control' [ http://www.astro-bab...dimmer.htm ]. I a little put off by the "Damage can easily result to the mount" comment, it is a new one after all. And, in my experience, damage does not have to result all that 'easily' for me to be able to achieve it! Looking round another forum, I came across a similar question and someone suggested trying to borrow a synscan handset from someone local and resetting the brightness, which apparently the mount will 'remember'. That might be a less potentially destructive solution!

There is a bit of a chicken and egg situation here. Until I have the scope properly polar aligned, I cannot be sure that Polaris is actually within the fov of the polar scope and so any adjustments I make trying to see it may be totally unnecessary/futile. Once I do have it accurately aligned, I would know that Polaris is there, but the polars cope bit has become a bit redundant.

Meridian limits:

Thanks also for the link to the EQMOD youtube videos [

]. {I have tried several times to get this to just give a link rather than embed the videos here, but I can't seem to achieve that} I am going to have to set aside a few hours to go through all 45, but the one on meridian limits certainly provided a lot of info that I did not previously have. I think it may be a case of setting it to do an automatic flip while I am just 'cruising around' different objects, and then set specific limits when I set on an object and start the imaging. At least, those are my thoughts atm, but (as always) this may change with experience!

Astrotortilla alignment:

And thank you also for the alignmaster link [ http://www.alignmast...master.de/ ]. I had been hoping that it would not be necessary to shell out on a piece of software to do what AT says it can do for free. But, €14 is not exactly going to break the bank. And one thing I definitely do like is that it takes the 'guesstimation' out of the adjustment process. Rather than having to adjust the knobs by how much you think it should be to move you 68.7', just adjust the knobs until the star is re-centred on the screen. I guess that would be much simpler. But I may try posting my question to the AT yahoo group first, just in case am doing anything obviously stupid.

Thanks.

[Russe]

I've tried both PA's right after each other and they result in quite different outcomes.

I wonder which one would be better.