Re: [APML] Re: How to use Pictor 208XT autoguider with Celestar 8

[Duncan Munro <dmunro@sfu.ca>]

jthirsty@charter.net wrote:

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>Thanks for the heads-up Duncan.  I tried operating R.A. and Dec simultaneously; if I press and hold R.A first and then press and hold Dec, not only will it not move in the Dec, it also won't start moving as soon as the R.A. button is released.  Apparently there has to be a period where there is no signal before it will switch between the two motors.  Obviously this could cause a problem if the guide star is drifting and the 208XT locks up the motor controller by constantly sending it simultaneous commands.
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>So that brings up another question: can programs like Guidedog and K3CCD be configured to not send R.A. and Dec commands simultaneously, or is it built into their telescope databases?
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I'm not familar with these programs but CCDSOFT, Maxim and Astroart 
have  a "delay after guide command" which IIRC, will prevent two 
commands from happening simultaneously. Maxim also has a check box to 
enable/disable simaltaeous guiding commands.

>I did a lot of reading and surfing yesterday and decided to try modifying a Quickcam 4000 for my first attempt, rather than blowing most of my budget on the 208XT.  Am I right in thinking that because it uses a USB connection for the guide camera it will be fast enough to prevent the low correction rate described above?  If anyone has any comments about this method, I would be glad to hear them.
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The low computer controlled correction rate for the 208xt is based on a 
firmware limitation. AFAIK, a ST-5, for example, does not have this 
problem and can probably achieve a 1 to 2 subframe per second download 
time. Apparently the 208xt's subframes can only be read by the computer 
after the "full" frame has been digitized.

>thanks,
>Jerry
>
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cheers

Duncan
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