Since a picture is worth a thousand words, the attached jpeg shows the glass retaining ring that threads into the cell or barrel; it usually has writing on it with the manufacturer, serial, model, aperture and so forth. This ring also in many cases determines how far the glass is from the iris as well as a way to remove glass for cleaning. Many Artars were more intelligently designed and had a knurled ring on the rear of the cell by which the glass could be removed for cleaning without resorting to spanners or O-rings to remove the front retainer.
Last edited by Steve Hamley; 07-10-2009 at 06:48 PM. Click to view previous post history.