Advanced CT Laser Collimator Manual (V9.0 =OH=) Page 6 of 20
3.0. Installing the Reflector Mirror:
3.1. Installing the Reflector Mirror into your visual back or focuser
If the telescope is to be used mostly for visual observation, collimation can be done with your star
diagonal in place. Please note that a poor quality diagonal, one with a misaligned mirror, may
cause collimation problems. However, if photography or CCD imaging is planned, it is best to
insert the reflector mirror directly into the telescope's visual back or focuser. Use either a 1.25-
inch or 2-inch reflector mirror depending on the size of visual back or focuser.
To properly install the reflector mirror, slightly pressure the reflector mirror shoulder against the
focuser rim. Rotate the mirror in the focuser and observe movement on any one of the visible
laser dots projecting on the collimator target plate. Gently turns the thumbscrew to lock the
reflector mirror in place without seeing any laser shifting.
NOTE – For best possible collimation with a diagonal, and if you plan to use a reducer, and/or
field flattener, first perform all the steps to collimate the telescope without the accessories, then,
refer to
Step 10.0
to collimate for use with the accessories installed. (The Celestron Edge series
of telescopes already has field flattener lenses installed; this does not change or affect any of the
steps or procedures given in this manual.)
4.0. Positioning the Laser Collimator at the Proper Distance
The distance between the laser collimator and your
telescope varies depending on the diameter and focal length
of your telescope. In general, the greater the distance from
the telescope, the higher accuracy you will achieve. In
practice, distances just beyond the Back Focal Length (BFL)
distance will give larger target patterns with good resolution.
Use the following steps to identify a good collimating
distance for the telescope.
4.1. Determine the distance between the laser collimator and your telescope
a. Position the collimator one tube length's distance in front of the telescope with
the target plate facing the telescope (photo above).
b. Switch the collimator to mode 1 (crosshair laser only).
c. Roughly aim the crosshair toward the telescope.
d. Experiment with the proper distance by lifting the tripod and collimator and
moving the collimator slowly toward and away from the telescope while keeping
the reflected crosshair on the target plate. Don’t worry about getting the
crosshair perfectly centered on the target at this point. You will see how the
crosshair contracts and expands in size on the target plate in relation to the
distance adjustments.
e. Move the collimator to the distance where the crosshair is its smallest. This
point is at the Back Focal Length (BFL) of the telescope primary mirror. Now, to
position the collimator at a distance with good pattern resolution, move the
target away from the telescope until the inner tips of the reflected crosshair are
positioned between the target plate’s ring 1 and 2.
f.
Firmly position the tripod at this distance. This will be your collimating distance.
5.0. Achieving Basic Co-Alignment of the Collimator and Telescope
This is the critical step where you achieve Basic Co-alignment of the Collimator and Telescope for an accurate reading of the
Telescope’s optics alignment.
Step 5.0
is broken down into three linked
Sub-Steps 5.1, 5.2, & 5.3
that must be repeated
(iterated) to lock-down Basic Co-Alignment. These iterative processes are similar in nature to the processes used to originally
align the telescope.
NOTE – DO NOT use the back of the secondary mirror housing as a crosshair centering reference. The secondary mirror
might not be perfectly centered on the optical axis of the primary mirror. Referencing the center of the back of the secondary as
the pointing axis does not mean the primary mirror is also on the axis. You can use it as a quick rough check for aiming, but
not to achieve co-alignment.
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