Tensioning screw changes focuser tube alignment
Posted 04 January 2013 - 10:35 AM
My inclination is to center the 2ndary with the focuser tube tensioned, as that reflects actual conditions of use. But I'm wondering, is there an adjustment so the tube alignment isn't affected by the tensioning screw?
Posted 04 January 2013 - 02:58 PM
Posted 05 January 2013 - 09:10 AM
Posted 06 January 2013 - 01:38 PM
: With the sight tube installed, release the tensioner screw so everything sits down on the shoulders.
: Now slowly tighten the tensioning screw and watch what happens to the axis of the focuser or, in my case, the sight tube.
On mine, the right side stays down against the shoulders but the left side (toward the OTA opening) "rides up" as the tensioner engages enough to be used. This tilts the focuser axis toward the front of the scope.
So, engaging the tensioner changes the focuser axis to such an extent that I can not adjust the secondary mirror enough to bring it entirely under the sight tube. It has the appearance of being be too far into the tube. But in fact, the real problem is that the tensioner tilts the focuser axis.
Any ideas? I don't see any adjustments on the outside.