Re: [APML]: Byers drive

["Tom Krajci" <krajcit@det5wg57.barksdale.af.mil>]

> From:          Chuck Vaughn <aa6g@aa6g.org>

> Generally I stick to 1 or 2 seconds. Up until Hale-Bopp in March I had
> never manually guided a photo with the 11 5/16" drive. My ST-4 was in for
> repair and I wanted to get a couple of photos. It was so easy to guide
> manually I couldn't believe it. It was such a struggle with the old 10"
> drive. The March photos of H-B on my web page were all manually guided.
> The star trails are all straight, none of the wigglely lines you see on
> most manually guided comet photos. Those other people must have had terrible
> drives. :-)

It may have not been just the drive.  Hale-Bopp was very easy to 
guide on. . .a stellar nucleus.  Last Fall I shot comet Tabur.  No 
nucleus to guide on (at least I couldn't see one).  That may be one 
reason for bad tracking if you're using a guidescope on a diffuse 
comet.  That's why I use drift guiding on a guidstar when shooting 
fainter comets.
 
> >I get the impression
> >from Astromart that DC steppers are more expensive than AC synchronous
> >motors. Would that be right?

In surplus catalogs DC steppers are from $2 to $60.

Tom Krajci

Capt Tom Krajci
B-52 Intelligence Officer
"There are only two possible outcomes in any war.
Operational success or intelligence failure!"
http://spur.barksdale.af.mil