From: albe albo <richter1956@yahoo.com>
Date: April 26, 2010 4:17:27 PM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Encoder self-correction question....
ok... got the messages about encoding pec etc...
back to Astro IIDC as is.
About batch align with manually selected points:
I already did all my 177 reference movies choosing a certain confidence.
This way the refence movies are already sorted with the 1st frame as the sharpest one. (isn't it?)
Using such reference movies could avoid to preprocess for sharpness estimation and it would be possible to batch select the alignment points on the first (sharpest) frame.
Perhaps my thought is wrong but perhaps it isn't...
Cheers
TTYL
Da: Milton Aupperle <milton@outcastsoft.com>
A: Astro_IIDC@yahoogroups.com
Inviato: Lun 26 aprile 2010, 21:13:25
Oggetto: Re: [Astro_IIDC] Encoder self-correction question....
Dear Alberto;
On 26-Apr-10, at 12:48 PM, albe albo wrote:
Hi Milton,
perhaps my english lacks a little because i'm not sure i understood your words.
No your english was fine.
The TDM device doesn't work on the mount's PEC but it continuously monitorize the AR axis while it is in a working session and it reads (always in real time) all the rotational errors of the mount and it makes continuous corrections. It could be used in addition to pec and in addition to the autoguide or it could be used to read the periodic error without stars but that is a very secondary usage.
I never said it did interact with PEC. I said it was like PEC and the best thing to do would be to record the corrections with PEC so that the device isn't always connected to your mount. In fact, I'm not 100% sure how it clamps onto the Telescope in the first place and if that interferes with anything.
.Basically it seems that a EQ6 could be easily corrected to +2 -2 arc sec then, but, if you want a higher precision, you may add the autoguide that will be more effective since it will have to correct a very sweet error of 4 arcsec peak to peak instead of a +-20 arcsec.
Yes but Autoguiding handles all of it (PEC, TDM and turbulence), so why waste a lot of money and a tonne of my time on something that needs to be corrected anyhow?
That device is stand alone: no computer, no pec needed: it does all the job by itself.
That was my idea: putting a precise encoder clamped directly on the RA axis and read the errors relative to an ideal sidereal motion. At this point astroIIDC should use the encoder information to guide realtime the precision of the mount. If the target is +- 2 arcsec i guess that it worth.
Anyway it could be a nice field for an experiment.
That isn't enough precision though for anything over maybe 1,000 mm focal length.
I'm frightened by the price of the encoders: i saw one with 0.28 arcsec resolution
http://www.gurley. com/Encoders/ Info/8x60. pdf
but i have no idea if it will cost 10-100-1,000- 10,000 usd.
Since the complete device sold by Meade is 1350 euros, i guess that industrial encoders would cost less than half or less again. Perhaps 200 - 300 usd could be enough.
After that, the pulse from the encoder must be transformed into a signal that could be handled by AstroIIDC in substitution of the guiding star (only for AR so it is simpler).
well well... who knows?
I hope to have solicited some curiosity or a... WHY NOT to TRY?
Unhunh. So rather than pay for an expensive product that already exists and is platform agnostic, you expect me to spend a tonne of time working on this "for free" for a Mac that has 3% market share of what Windows has? Wanna bet that even if I built it for free, maybe 5 people in the entire world would use it? It isn't worth my time looking into it any further as there will be zero return on investment.
Frankly, a better use of my time rather than working on some home brewed solution for a miniscule number of users would be to look into the Orion SteadyStar AO than this.
Right now I'm debating whether I should do the PGR USB coding because sales of Astro IIDC are borderline as it is and the number of people whom requested USB 2/3 support are miniscule. I doubt if my return for new customers would recover costs of buying one the USB Cameras for testing / development purposes.
Please Milton, returning on the batch multipoint alignment: can i choose all the point in the movies before, memorize them and then launch the multipoint alignment process night time?
No you can't.
Astro IIDC needs to know what is the sharpest frame before it can present the image so that you can pick the MAP points. Therefore it has to do a lot of processing before it gets tot he stage of picking your MAP's. I'm not about to re-write a tonne of code just so this will happen.
Hope that explains things..
Milton J. Aupperle