| The focus is motorized using a worm driven mini-winch driving a line wrapped around the rotating focuser ring. A limited amount of adjustment is available. The focusing ring handles (the 3 posts shown in the figure) were removed and a pulley was fabricated that bolts to the ring.
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| The focuser and the top of the baffled tube are shown here. The lines around the pulley will be routed so that they fall in the shadow of one of the spider vanes. It is difficult to photograph black objects over a black background, isn't it?
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| The focuser pulley lines are routed temporarily to the focuser motor box via some rings for one line and a sysem of pulleys and bungee cord for the other. Two opposing pulleys were tested, but variability in the tension of the lines caused problems. The work around is to use one pulley in push/pull motion while the elastic cord applies tension at all times. Because of the large ratio of motion (approximately 60 cm of motion of the pulley line to 1 cm of focuser motion) the length of the elastic cord limits the focuser travel. Once approximately set, the focuser should serve adequately to maintain focus.
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