Meade 2045 - Alignment of the Optical System

from the main tube).
Importantly, do not remove the actual correcting lens from its machined cell housing for cleaning or other
purposes. You will almost certainly not be able to replace the correcting lens in its proper rotational
orientation, and serious degradation of optical performance may result.
Alignment of the Optical System
All Meade Schmidt-Cassegrain telescopes are precisely collimated (aligned) at the factory before packing
and shipment, and it is probable that you will not need to make any optical adjustments before making
observations. However, if the telescope sustained rough handling in shipment, you may need to
recollimate the optical system. Such recollimation is not difficult, in any case.
To check the collimation of your telescope, locate in the telescope a moderately bright (first or second
magnitude) star near the zenith. To perform the test, center the starpoint in the telescopic field with a low
power eyepiece, such as the 25mm eyepiece supplied as standard equipment. Defocus the image to fill
about 1/4 of the field of view. You will see in the out-of-focus image a circle of light with the darker
circular shadow of the secondary mirror somewhere within. If the darker shadow is well centered within
the lighter shadow(see (C), Fig. 4), your telescope is well collimated, but continue to read this section for
the more sensitive, high power tests to be described below. If the darker shadow is not so centered (see
(A), Fig. 4), follow this procedure:
1. Locate the three collimation set screws near centrer portion of the front corrector plate lens (see Fig. 3).
2. Note that the only optical alignment adjustment of the Model 2045 that is ever necessary or possible is
the tilt-angle adjustment of the secondary mirror. Adjustment of this tilt-angle is achieved by turning the 3
set screws (2), (3) and/or (4) in Fig. 3, located at the edge of the secondary mirror housing.
DO NOT AT ANY TIME TURN OR ADJUST THE CENTER SCREW (SEE (1), FIG. 3), LOCATED ON
THE OUTER SURFACE OF THE SECONDARY MIRROR HOUSING. THIS SCREW HOLDS THE
SECONDARY MIRROR IN PLACE IN ITS HOUSING!
DO NOT FORCE THE 3 COLLIMATION SET SCREWS PAST THEIR NORMAL TRAVEL AND BE SURE
TO KEEP AT LEAST ONE SCREW UNDER TENSION AT ALL TIMES SO THAT THE SECONDARY
MIRROR WILL NOT ROTATE IN ITS HOUSING. NOTE THAT THE SECONDARY MIRROR
COLLIMATION ADJUSTMENTS ARE VERY SENSITIVE: GENERALLY, TURNING A SET SCREW 1/2
TURN WILL HAVE DRAMATIC EFFECTS ON COLLIMATION.
3. While observing the defocused star image, note the direction in which the darker shadow is offset
within the lighter circle. Using the telescope’s slow-motion controls, move the defocused image to the
edge of the field of view, in the same direction as the darker shadow is offset.
Fig. 3: Collimation of the Optical System
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