Convertible lens

convertible lense's inscription

A convertible lens is a lens consisting of at least two separatable parts, each containing a part of the lense's elements. 100 years ago these were a common option for photo amateurs to give a double or triple extension folding camera more versatility. The common lenses of that era consisted of a pair of lens tubes, one to screw into the back of an aperture/shutter-unit, the other to be screwed into its front side. Mounted that way the lens element groups of both lens tubes gave the complete standard lens, useable with single extension of the camera bellows. Mounting only one of the lens tubes meant to switch to a tele focal length which needed double or triple bellows extension.

Glossary Terms