Note: A small paper ring is attached to the primary mirror. This ring was attached at the factory for purposes of laser collima- tion. The ring will not dimin- ish your telescope's imag- ing capabilities and does not need to be removed.
8
PreciseCOLLIMATIONcollimation, orOFalignment,THEofOPTICALyour telescope’SYSTEMs optical system is essential for good performance. All Meade telescopes are accurately collimated at the factory prior to shipment. You may want to collimate after the telescope has been shipped or if it has endured rough handling or a bumpy car
Meade offers an optional laser collimator to help you to collimate your telescope (see PTIONAL ACCESSORIES, page 18). Nevertheless, take the time now to familiarize your- selfO with the following collimation procedure so that you may recognize a properly
collimated instrument and adjust the collimation yourself, if necessary.
TheCorrectcollimationCollimationprocedure for the Meade LightBridge Dobsonian is slightly different from that of other Newtonian reflecting telescopes, because of the "fast" f/5 to f/6 focal ratio of the primary mirror. In typical Newtonian reflectors with more conventional focal ratios (i.e. longer focal ratios), when the observer looks down the focuser tube (with- out an eyepiece in the focuser), the images of the diagonal mirror, primary mirror, focuser tube and the observer's eye appear centered relative to each other.
However, with the short focal ratio primary mirror of the LightBridge Dobsonian, cor- rect collimation requires that the diagonal mirror be offset in 2 directions: (1) away from the focuser and (2) towards the primary mirror, in equal amounts. This offset is approximately 1/8" in each direction. Note that these offsets have been performed at the factory prior to shipment of your telescope. It is only necessary for you to confirm that the telescope has not been badly jarred out of collimation, and to perform the final
shows a correctly collimated LightBridge Dobsonian telescope, as it appears whenFig. Dviewed through the focuser with the eyepiece removed.
To check and, if necessary, set the optical collimation, follow these steps:
1. Observe through the focuser and orient your body so that the telescope's primary mirror is to your right, and the open end of the telescope tube is to your left.
The diagonal mirror will appear centered as shown ( ). If the diagonal appears off center, then adjust the 3 collimation screws ( 2, Fig. )Don the plastic diag-
onal mirror housing.2, Fig. B
2. If the reflection of the primary mirror ( ) is not centered on the surface of the diagonal mirror, adjust the 3 collimation3, adjustmentFig. D screws on the diagonal mirror housing to center the reflection.
As described above, the 3 collimation screws on the diagonal mirror housing are used for two different adjustments during the collimation procedure.
Do not force the 3 screws past their normal travel, and do not rotate anyImportantscrew orNote:screws more than 2 full turns in a counterclockwise direction (i.e., not more than 2 full turns in their "loosening" direction), or else the diagonal mirror may become loosened from its support. Note that the diagonal mirror collimation adjust- ments are very sensitive: generally turning a collimation screw
3. If the reflection of the diagonal mirror is not centered within the reflection of the pri-
mary mirror, adjust the 3 collimation adjustment screws ( ) located on the
rear of the primary mirror cell.20, Fig. C
Proceed by "trial and error" until you develop a feel for which collimation screw to turn in order to change the image in any given way.
4. Perform an actual star test to confirm the accuracy of steps 1 through 3. Using the 26mm eyepiece, point the telescope at a moderately bright (second or third magni- tude) star, and center the image in the main telescope's field of view.
Looking at or near the Sun will cause irreversable damage to your eye. Do not point this telescope at or near the Sun. Do not look through the telescope as it is moving.
