Apertura Dobsonian Telescope, Owner'S Manual

Page: 15 / 22

10:1 Precision Micro Crayford Style Focuser
Your Apertura Dobsonian Telescope comes standard with a Dual-Speed 10:1 focuser. It is
pictured here with the drawtube fully extended.
The Apertura focuser will
accept 2“ and 1.25” eyepieces
(with included adapter) and
other common hardware. The
amount of extension required
for each eyepiece will vary,
therefore retract or extend the drawtube to bring the image
into focus. For lower power, wide field-of-view (FOV)
eyepieces, it may be necessary to increase the focal length by fitting the
35mm Extension
Tube into the focuser as an adapter to achieve focus.
The movement of the focuser tube is a result of tension inside the focuser which can be
adjusted by the tensioning screw. In general, use the lightest amount of tension that will
work with the installed components for smooth action. But as heavier eyepieces are used,
especially in conjunction with other components, increase the tension to compensate for
the extra weight.
Once you achieve focus, you may want to use the locking screw to hold the focuser in place
even if the adjustment wheels are moved. This is helpful when exchanging parfocal
eyepieces or having other viewers come to the eyepiece.
1/10 speed
adjustment wheel
Full speed
adjustment wheel
Brass Compression Ring
Compression
Adjustment Screws
Tensioning Screw
Locking Screw
Focuser Drawtube
extended
The scale on top shows the
focuser drawtube fully extended
to 4cm or 1.5”.
!! IMPORTANT !!
Locking screw (under tensioning
screw) must be backed out to
allow full drawtube travel.