HINTS TO DETERMINE IF
THE BLACK PHILLIPS FACTORY COLLIMATION SCREWS ON THE CELESTRON C8 HAVE
STANDARD OR METRIC THREADS
PHOTO
FEATURES
TYPE OF COLLIMATION SCREW
Smooth secondary surface with serial number
sticker.
Standard or metric
Textured secondary surface with serial number
sticker and "Celestron" imprint. Collimation screws are surrounded by normal
surface texturing.
Standard
Textured secondary surface with serial number
sticker and "Celestron" imprint. Collimation screws are surrounded by a
thin ring of smooth plastic and are slightly countersunk into the secondary
housing. This is the most common black Phillips configuration.
Metric
If you decide to remove a C8
collimation screw, here's how to determine if the screw has standard or metric threads. (Our knobs are shown in
the photograph.) Both factory screws have about the same thread length below
the screw head. The metric screw is slightly smaller in diameter, but that
isn't really helpful without having samples of both screws. The best
way to determine screw type is to count threads. The standard screw has
about 10 thread turns over its 5/16 inch length, and the metric screw has
about 16 thread turns over its 8 mm length. (Exception: The C8 with EdgeHD
optics has a longer 12 mm black Phillips secondary collimation screw. This
screw is metric with 24 thread turns over its length.)
