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Your Explore Scientific Dobsonian is a precision optical instrument and should be used with care. Try to avoid
exposing your telescope to vibrations because this may cause the telescope to lose collimation.
Aligning the viewfinder
The red dot that is used by the finder scope is not readily visible during the day. For this reason you should align the
finder scope once it is dark.
To do this:
1. Insert an eyepiece with low magnification into the focuser of the telescope and make sure that the red dot finder
scope has loaded batteries and is switched on.
2. Look through the eyepiece and center an object that is easy to find at a minimum distance of more than 800
yards, like a street lamp.
3. Look through the red dot finder and move your head until you see the red dot of light that is projected onto the
glass window. Adjust the finder with the two screws until the red dot is on top of the object that is centered in the
telescope’s eyepiece. You can fine-tune the finder collimation on a celestial object, like a bright star or a crater on
the moon, by following the same procedure.
Focuser
The focuser of the Explore Scientific truss Dobsonian is a single speed focuser.
Important: Never try to force the focuser beyond the stops. Do not turn the focuser
knobs while the focuser is locked. Turning the focuser knobs while the focuser is locked
may result in damage to the focuser.
The telescope comes with two extension tubes, 25mm and 20mm tall. This is needed
so the eyepiece can focus. One 25mm extension tube comes pre-installed and the
second 20mm extension tube can be added as needed depending on the eyepiece
magnification.
To install the 20mm extension tube, unthread the adapter and 25mm extension tube together from the draw
tube. Thread the second extension tube onto the draw tube then thread the adapter and 25mm extension tube
onto the second extension tube, Figure 13. Your included eyepiece can now be inserted to the 1.25in adapter by
untightening the tension screw, sliding in the eyepiece and tighten the tension screw to tighten the compression
ring lock, Figure 14.
Your telescope is compatible of using 2in eyepieces, sold separately, by loosing the three tension screws from the
tension collar and removing the 1.25in adapter.
Important: The tension collar is equipped with threads that will allow users to attach a camera to the telescope.
However you will need a camera specific device called a T-ring (sold separately) that goes between the tension
collar and the camera.
Using Your Dobsonian
Figure 13
Figure 14
25mm Extension Tube
& 1.25in Adapter
25mm Extension Tube
& 1.25in Adapter
20mm
Extension Tube
Eyepiece
Adapter
Tension Screw
1.25in
Adapter
Tension
Collar
Collar’s Tension
(3) Screws
Extension
Tube
Draw
Tube
