User Manual
40
the opposite direction and bring the image back to the
centeroftheeld.
5. If the screw you are turning becomes very loose,
tighten the other two screws by even amounts. If
the screw you are turning gets too tight, un-thread
the other two by even amounts.
6. When you bring the image to center,
carefully examine the evenness of the ring
of light (concentricity). If you nd that the dark
center is still off in the same direction, continue to
make the adjustment in the original turning
direction. If it is now off in the opposite direction,
you have turned too far and you need to turn in
the opposite direction. Always double check the
imageinthecenteroftheeldoftheeyepiece.
7. You may nd after your initial adjustment that the
dark center is off in a new direction (e.g., instead
of being off side-to-side it is now off in an up-and-
down direction). In this case repeat steps 2 through 6
tondthenewadjustmentscrew.
8. Now try a higher power eyepiece (e.g., 9mm or
less) and repeat the above tests. Any lack of
collimation at this point will require only very
slight adjustments of the three set screws. You
now have good collimation of the optics.
9. As a nal check on alignment, examine the star
image in focus with the higher power eyepiece
as suggested above, under good viewing
conditions. The star point should appear as a
small central dot (commonly referred to as an
“Airy disc”) with a diffraction ring surrounding it.
To give a nal precision collimation, make
extremely slight adjustments of the three set
screws, if necessary, to center the Airy disc in the
diffraction ring. You now have the best alignment
of the optics possible with this telescope.
Collimating the Maksutov-Cassegrain Optical
System
The only optical component that can be adjusted in the
LX65 Maksutov-Cassegrain is the tilt of the Primary Mirror.
The front corrector and secondary mirror are permanently
aligned. This makes collimation overall fairly straightforward.
Follow these steps to inspect and adjust the alignment of
your optical tube.
Collimate Using the Star Test
1. At night, point the telescope to a fairly bright star that is at
least 60º above the horizon. This will ensure the star is above
Collimating the ACF Optical System
1. The only adjustments possible, or necessary, on
the ACF are from the three inner most screws
located at the inner surface of the secondary
mirror housing.
CAUTION: Do not force the three collimation screws
past their normal travel and do not loosen them more
than two full turns in a counterclockwise direction or
the secondary mirror may come loose from its support.
You will nd that the adjustments are very sensitive,
usually requiring only one-half turn or less to produce
the desired result.
2. While looking at the defocused star image, notice
which direction the darker shadow is offset
in the ring of light or notice which part of the
ring is the thinnest. Place your index nger in
front of the telescope so that it touches one
of the collimation set screws. You will see the
shadowofyourngerin theringoflight.Move
your nger around the edge of the black
secondary mirror support until you see the
shadow of the nger crossingthethinnestpart
of the ring of light. At this point, look at the front of
thetelescopewhereyourngerisaiming.Itwill
either be pointing directly at a set screw, or it will
be between two set screws aiming at the set
screw on the far side of the black secondary
mirror support. This is the set screw that you will
adjust.
3. Using the Arrow keys at the slowest slew speed,
move the defocused image to the edge of the
eyepieceeldofview,inthe same directionas
the darker shadow is offset in the ring of light.
4. Turn the set screw that you found with the
pointing exercise while looking in the eyepiece.
You will notice that the star image will move
across the eld. If while turning the defocused
star image ies out of the eyepiece eld, then
you are turning the screw the wrong way. Turn
Collimation Screws