The annotated photos below will serve as an illustrated glossary; they identify all the key parts of a Newtonian Optical Tube, first from the front, then from the rear, with a telescope that is similar but not identical to the one we are building. We also point out some major parts of the Dobsonian mount that are visible in the photos.
This scope was built by Jay Drew, STM, following the design given in [Kriege97] for small Dobs. The mirror is a 8-inch f/6 which Jay made himself. The front view shows a commercially made spider, focuser and reflex finder. The rear view shows a cast aluminum mirror cell purchased from a telescope supply vendor.