Posted by Les Newcomer on August 16, 2000 at 20:39:04:
In Reply to: Lens Maintenance Question posted by Jeff Dilcher on August 16, 2000 at 17:02:03:
A lens is comprised of two cells (front and back) seperated by a
barrel or shutter. Within the cells elements (single glss
components) are arranged in groups separated by a large air space.
For example a Tessar has 4 elements in three groups, The front and
center are single elements in the front cell, the reer cell hold
two element cemented together.
Some lens designs like the Protar series Vii, Dagor and old Symmar
were convertible, these lenses allowed different focal lengths by
using the front or reer cell by itself. (I know how to spell reer,
but the profanity check prevented me from using it correctly!)