Originally posted by davids8560 What's unsatisfactory with setting the aperture electronically, as opposed to doing it by a ring around the lens?
Having a camera that does not do that? Older film cameras do not always allow setting the aperture electronically.
Also, if you are adapting the lens, for example to use on Sony or Canon, the aperture ring is needed in most cases.
Also, if you are going to use extension tubes, bellows or many TC's you need the aperture ring because many of those things are older and do not have the contacts to pass the aperture info along to the camera. Some do, of course but many don't and the ones that do are more expensive.
But there is nothing magical about having an aperture ring on the lens, if you have a modern DSLR and don't use manual accessories then it really does not matter. The high value of the older lenses is not just because they have an aperture ring. The construction and feel is highly valued as well as the older rendering. Also, the long focus throws of older manual focus lenses is highly valued for video.