You guys are going to love this video of the making of a Leica lens. Admittedly, I have never owned a Leica camera or lens, but their reputation is world-renowned and it's worth seeing the care that they do put into their products. For what it's worth, many Canon lenses are hand-assembled as well (certainly the “L” lenses are) and the effort pays off.

Leica Lenses (English) from leica camera on Vimeo.