Why is there no mount with auto-polar-align?

[AndrewJ]

Gday Fred

Ive discussed this with Andrew before (yours is taking too long to make Andrew http://www.iceinspace.com.au/forum/..../pokestick.gif http://www.iceinspace.com.au/forum/....s/tongue05.gif),

The Melbourne weather saps ones desire at times
But i do have the DEC done.

I can currently watch through my EP and do a smooth "controlled" manual move in Alt or Az of around 10 arcsec, using only 2 fingers.
Using the motor in DEC, its even smoother.
However, i am also using 1/2" UNEF threads on a lever arm of 280mm to do my moves.
When you look at the very short lever arms and coarse threads on most cheaper GEMs, the ability to do low power fine adjusts just isnt there.

Also, why I plan to use the drifting method, vs TPoint etc as
1) Its exceedingly cheap
2) I dont need encoders etc, and dont need to account for any lash in the adjusting mechanism. Just watch the star and move accordingly
3) I was thinking that if you used drifting, at any time during the night,
if you slew to a new locn, you could start a quicky drift test and if necessary, get the mount to micro adjust itself for that locn
This removes all the refraction, flexure etc effects,
and means no complicated models are reqd.
Just point and tweak.

Andrew

[wysiwyg (Mark)]

Interesting conversation!

I have often wondered how you would go about automating polar alignment. I think without a CCD/Camera feedabck system it would be fairly inaccurate but not impossible.

Having used TPoint with the PME, the process of polar alignment is fairly simple.

1. Level the mount as best you can
2. Point roughly to SCP
3. Home and point telescope to a star as near the home position
4. Take live images and move DEC/RA manually until star in FOV.
5. Center star on CCD chip using Maxim DL
6. Sync
7. Start new TPoint model (6 points minimum)
8. After having slewed to and centered all 6 stars, Tpoint will provide DEC/RA adjustment info fro the PME.
9. Adjust mount accordingly
10. Your done.

Mind you this is the process with a PME as TPoint provides the exact number of tics to move the RA and DEC adjustments.
This will give you a fairly accurate polar alignement but not perfect.

The above process takes about 15 minutes.

It would be fair to say that if TPoint knows exactly what adjustements to take, there would be no problems sending a signal to a couple of servo motors to make the adjustments in tics.

Keep in mind, as soon as you do make adjustemnts you effectively have to re-do the TPoint model. This is a reiterative process to fine tune polar alignment.

To get spot on polar alignment and for pro-track to work effectively you need a 300 point + model to work with, not to mention tweaking the terms and eliminating outliers in your sample size. In my experience this is worth doing when you have a permanent obs, but an overkill for field use. I find a 30 Tpoint point model gets you close enough in the field.

So in motorising the polar alignment and given that the above procedure takes 15 minutes, one would ask if its worth the effort.
The only benefit you would gain in the field is that you would not have to get up from your chair to do it :-)

Mark

[Bassnut (Fred)]

Mark

The free AAG Tpoint mapper will *automatically* do a 40 point map in 10mins (with Tpoint/pinpoint and Sky on a PME) . Very tedious manually .

[rogerg (Roger)]

Several people have commented it's quick to do a polar alignment so why bother..

A person proficient with polar alignment can do a good alignment in under 30 minutes. I don’t think there’s any argument that polar alignment can be “quick” and effective using conventional means, but .. that doesn’t stop me looking for a better way

If I can plonk down my mount in a field and turn it on, then tell it to polar align, I’d gladly spend my next 30 minutes eating my dinner or chatting to others or planning what to observe, rather than concentrating on timings and fiddling with adjustments

It’d also make accurate polar alignment much more accessible to newbies.

It’d also add more “gadget factor” to my setup, which some of us enjoy

I don’t see the need for such a feature in permanent setups, it’d almost be a waste of a few good motors and sensors Even my LX200 classic on wedge only needs a 10 minute test and tweak every few months.

I’m enjoying reading the discussion of pros and cons, believers and non-believers

[wysiwyg (Mark)]

Originally Posted by Bassnut

Mark

The free AAG Tpoint mapper will *automatically* do a 40 point map in 10mins (with Tpoint/pinpoint and Sky on a PME) . Very tedious manually .

Yes, thats exactly what I use for larger TPoint models.
You still need that first six or so that are done manually before engaging TPoint mapper though.

[wysiwyg (Mark)]

Originally Posted by rogerg

It’d also make accurate polar alignment much more accessible to newbies.

I agree whole heartedly, but unfortunately most newbies start off with mounts similar to EQ5's and EQ6's because they are cheap and a great starting point.
However these mounts as you know do not have the mechanical precision required to introduce things like motors to control the ALT and AZ.

Take an EQ6 for example, the ALT adjustment is a two way mechanical process, you undo one bolt to do up another. Unless you heavily modify the base it would be impossible to achieve automated polar alignment, not to mention the cost.

Because all mounts are so different having one system to work for all would also be impossible to implement.

Its not until you get to the PME or AP class mounts where you have the mechanical precision available to you to be able to make such improvements effectively.

Pushing one button to polar align would be nice though

Mark

[Bassnut (Fred)]

Originally Posted by wysiwyg

Yes, thats exactly what I use for larger TPoint models.
You still need that first six or so that are done manually before engaging TPoint mapper though.

mmm, whys that?. I havent needed to.

[Bassnut (Fred)]

Originally Posted by AndrewJ

Gday Fred


The Melbourne weather saps ones desire at times
But i do have the DEC done.

I can currently watch through my EP and do a smooth "controlled" manual move in Alt or Az of around 10 arcsec, using only 2 fingers.
Using the motor in DEC, its even smoother.
However, i am also using 1/2" UNEF threads on a lever arm of 280mm to do my moves.
When you look at the very short lever arms and coarse threads on most cheaper GEMs, the ability to do low power fine adjusts just isnt there.

Also, why I plan to use the drifting method, vs TPoint etc as
1) Its exceedingly cheap
2) I dont need encoders etc, and dont need to account for any lash in the adjusting mechanism. Just watch the star and move accordingly
3) I was thinking that if you used drifting, at any time during the night,
if you slew to a new locn, you could start a quicky drift test and if necessary, get the mount to micro adjust itself for that locn
This removes all the refraction, flexure etc effects,
and means no complicated models are reqd.
Just point and tweak.

Andrew

Yes, I can see iteritave drift adjustment working nicely, and cheaper, and easier to manage software wise, but it would take longer, not that that matters much.

Now get it done Andrew, enough Blah

[wysiwyg (Mark)]

Originally Posted by Bassnut

mmm, whys that?. I havent needed to.

Fred, that's a good point actually!

I just read the AAG pdf manual and it says to check the following:
"A TPoint model is available in TheSky6. Note that, if a new model is used in TheSky6, the telescope should be synchronised over a known star"

I guess you can get away without even doing the first six manually and let TPoint mapper do its work. As long as the synced star is in the field of view and roughly centred then pinpoint should do the rest.

Thanks Fred, you just saved me another 5-10 minutes off my polar aligning :-)

[AndrewJ]

Gday Fred

Yes, I can see iteritave drift adjustment working nicely, and cheaper, and easier to manage software wise, but it would take longer, not that that matters much.

Soooooo correct.
Rock up to Izzos,, plonk down the scope
Start it drift aligning then
down some plonk and wait for the pig to roast
( and the IzzoCirrus to form )
Meanwhile, the scope can align itself.
Ahhhhh, Norm would be proud.

Andrew

PS I reckon timewise wouldnt be such a big difference,
as with a webby watching the drift, vs a bloodshot eyeball
it wont take long on each axis
vs waiting till its dark enuf to do a Tpoint run
then adjust
then do a new TPoint run and adjust
then do another ??????
All comes down to how accurately you can adjust the axes
and as noted, yr bog std EQ units have no precision when it comes to this.

[duncan]

Hi All,
Just back from the bush!! Nice to have home comforts again.

However this statement sums itn up!!!!

"Because all mounts are so different having one system to work for all would also be impossible to implement."
Thanks Mark.

Nobody seems to want to work together for the betterment of all anymore.
Imagine how far advanced we could be if everyone worked together for a change?

We would all have huge scopes, just plonk 'em down and within seconds be able to take extraordinary photo's within minutes and then spend the rest of the night with the Missus or Hubby. Damn we wouldn't want that now would we.Haha!!!!!!!
Ah Well ONE DAY!!!!!!!!!!
Come on Andrew! Hurry it up,LOL
Cheers,
Duncan

[AndrewJ]

Gday Duncan

Ah Well ONE DAY!!!!!!!!!!
Come on Andrew! Hurry it up,LOL

Geez, i can start to feel the whipmarks again

However, my wedge was specifically designed to
allow me to "easily" load a 10" LX200GPS scope
Ie, it folds down flat to allow me to fit the scope in an
Alt/Az position, then the wedge folds back up into position.
Its just a side effect that this design lends itself to
Motorisation of the wedge axes.
As mentioned by others, i also dont see how
a std wedge or EQ type head could be done cost effectively
and i doubt my homemade wedge could ever be made
cost effectively either.

Andrew

[TrevorW]

why is this a good idea

a) not everyone has a permanent site
b) I for one have the SCP blocked by my roofline
c) who wants to stuff around every time they set up aligning and drift aligning etc

[allan gould]

I don't know how many times Ive offered this up, but Alignmaster will get you polar aligned with two iterations that takes about 5 min total. Never use anything else. And you dont need to see the pole.

[TrevorW]

Tried it can't make sense of it Allan never seems to work for me

[Bassnut (Fred)]

Originally Posted by wysiwyg

As long as the synced star is in the field of view and roughly centred then pinpoint should do the rest.

Dont even bother with that, just click and go ;-)

[marki]

Originally Posted by allan gould

I don't know how many times Ive offered this up, but Alignmaster will get you polar aligned with two iterations that takes about 5 min total. Never use anything else. And you dont need to see the pole.

Yep it takes a couple of minutes (as long as you can see the required stars) and does a very good job of accurately polar aligning the mount.

Mark

[TrevorW]

School holidays coming up Marki if we get a fine night you can show me how too get this working Cheers

[sejanus (Gavin)]

Originally Posted by allan gould

I don't know how many times Ive offered this up, but Alignmaster will get you polar aligned with two iterations that takes about 5 min total. Never use anything else. And you dont need to see the pole.

Allan, does it get you close enough for astrophotography? Or do you still need to drift align to finish it off? I've read differing opinions.

[allan gould]

Originally Posted by sejanus

Allan, does it get you close enough for astrophotography? Or do you still need to drift align to finish it off? I've read differing opinions.

Several people that I have pointed out this program to, now use it entirely for their polar alignment. In severe cases they have no way of seeing anywhere near the pole and have a limited set of alignment stars. You can edit (carefully) the sterne file and put in your own set of alignment stars. Peter_4059 did just that as he images in a very restricted field of view due to backyard trees etc.
I used three iterations for my observatory based scope and have not had to touch it since. No drift aligning necessary. Prior to my observatory I would set up each night, polar align using Alignmaster (1 or 2 iterations), start PhD guiding and photograph with at least 10min subs. But if you want to check it use a drift alignment or K3CCDTools.