Auto Ring and Double Cable Release
When doing close-up and macro photography with bellows, the genuine Konica extension rings, or the lens reverse-mounted with a reverse adapter, the automatic aperture functionality is lost. The aperture cannot be closed automatically by the camera body, because there is no mechanical coupling between the body and the lens any more. In this case, the light metering has to be made with the match-needle system and the lens must be stopped down to the desired aperture manually before exposure.
With the Auto Ring, the manual closing of the aperture is no longer necessary. The fully automatic AE exposure control is still not possible and the match-needle metering has still to take place. But after metering is finished, you can open the aperture with the Auto Ring and focus with open aperture and bright viewfinder image. When releasing the shutter, the matching Double Cable Release in a single action first closes the aperture to the preset value and afterwards triggers the shutter – it is not necessary to close the aperture manually.
Besides being more comfortable, this has the advantage of eliminating the danger of moving the whole setup accidentally while setting the aperture and thus producing out-of-focus images – with the minimal depth-of-field when using extension rings or bellows, a very small displacement can already be critical.
The Auto Ring can be used with the lens in its normal orientation as well as in reverse orientation. The Auto Ring is always mounted on the back end of the lens, where the aperture lever is – in reverse orientation, it is between lens and subject, in normal orientation between the lens and either camera body, extension rings, or bellows.
The Auto Ring can also be used as an extension ring with an extension of 14 mm (9/16").
The name Auto Ring 2 AR supposes that there was an earlier version, but I have no information about it.
For use with the electronic bodies of the F series, a different Double Cable Release is required, which combines the electric 5-pin plug for the camera body and the mechanical cable release for the Auto Ring. Such a Double Cable Release was available from Konica.