RE: [APML] OT: St-4 -help!

["Gene Horr" <genehorr@houston.rr.com>]

What kind of mount do you have?  If everything is set up correctly
you shouldn't need the backlash compensation.

In RA you should be guiding with less than 1X siderial corrections.
Since the gear never reverses there should be no backlash.  The
motor is merely speeding up and slowing down.

In DEC the corrections should be very rare, compensatiting
for system flexure or a slight bit of drift.  If you are 
continually changing directions you are chasing seeing.  In
that case you would need to either increase your exposure time
or use averaging.

For most systems the flexure is so slight that having to wait
a couple of cycles for the DEC worm to move to the other side
does not affect the final image.  You might want to try leaving
a slight imbalance in DEC in order to keep the gears loaded to
one side.

Try it with a slow correction speed and no backlash compsensation.
You should get better tracking.

Gene Horr




> -----Original Message-----
> From: astro-photo-bounces@seds.org
> [mailto:astro-photo-bounces@seds.org]On Behalf Of Ider Ivan
> Sent: 09/18/2005 11:50 AM
> To: Discussion of Film Astrophotography
> Subject: [APML] OT: St-4 -help!
> 
> 
> Hi Guys!
> 
> Several weeks ago I had purchased a brandnew(!) st-4 autoguider. 
> I'm in the 
> learning phase still, but I have an uncovered problem with the camera.
> 
> There is a problem with the backlash compensation, which seems to 
> works not 
> properly.
> The problem is: when st-4 change the direction in Dec, it applies the 
> increased correction time (due to H2 setting) TWICE, resulting a 
> completely 
> false correction.
> 
> Does anybody has any idea what might be the problem?
> 
> Thanks:
> Ivan 
> 
> 
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