Reversing rings are adapters with a male filter thread on one side and a rear lens mount on the other. The lens is attached to the reversing ring by its filter mount, and therefore the front element of the lens is closest to the camera. Most lenses are designed to give best results with lens-to-film distance less than the lens-to-subject distance, and so if you want to use an ordinary lens for macro work, it may give better results when reversed.
Because the reversed lens is attached by its filter mount, you are not restricted to using lenses designed for your camera system. You can even reverse enlarging lenses.
If the lens that you are reversing incorporates floating elements for better performance at short distances (like some macro lenses and fast wide-angle lenses), then you should make sure that the lens is set for close focus, not for infinity focus.
Reversing rings are not suitable for all cameras - some brands do not allow the lens to be stopped down when it is mounted in reverse. Some lenses, particularly zoom lenses, have a complex optical arrangement that does not produce good results (or may be impossible to focus) when used in reverse. Long and/or heavy lenses should not be reversed, because they would place too much strain on the filter mount.
To increase the magnification provided by a lens on a reversing ring, use extension tubes or bellows between the ring and the camera body. For small amounts of extension, use screw-in filter mounts (filters with the glass removed).
To retain the automatic diaphragm of reversed Olympus OM lenses, use the front standard of the genuine Olympus bellows, which allows the diaphragm to be operated with one side of a double cable release. This allows you to use Olympus lenses on any camera for which a reversing ring is available, not just Olympus cameras.
To convert the diaphragm in Olympus OM lenses to click-stop operation, add a manual extension tube or use a Retrostep from SRB Film Service. Kiron used to make an Olympus OM reversing ring (called a Reverse Mate) which was supplied with a separate ring for converting the diaphragm to click-stop operation.
The front standard of the genuine Olympus bellows can be reversed, allowing heavy lenses to be reversed (because the standard, not the filter mount, bears their weight). The reversed lenses can be fitted either to an OM body (fitted with a reversing ring and focusing stage) or to the bellows (which have a built-in clamp-on 51mm fitting).
You can control the diaphragm of reversed Canon FD lenses by using a Retrostep from SRB Film Service. The Kiron Reverse Mate used to come with an adapter for the same purpose.
Canon EOS lenses can be reversed and retain full functionality by using the special adapters manufactured by Novoflex, but only on EOS bodies.
Reversing a lens exposes the rear element and various coupling mechanisms that are protected when the lens is mounted normally. Turning the focusing ring may extend the outer part of the lens to provide some protection for the rear element; this works with Olympus OM lenses. You can also provide some protection by adding a short extension tube to act as a makeshift lens hood; an old manual tube will do fine. You can also buy Retrostep rings from SRB Film Service that allow a filter, lens hood or ring flash to be attached to the rear of a lens.
|Focal length||Working distance||Subject size||Magnification|
|50 mm||110 mm||55 × 37 mm||0.65|