This is probably a question that has been asked and answered a thousand times, but I can't find the answer. I have a Nikon 12-24mm G lens which I use on my D200. I have been thinking to use it on my Nikon FM2n when it dawned on me that there is no aperture ring and therefore no way to change aperture. Any ideas, because I would love to use the lens to shows its true wide capabilities. I know there may be an issue with vignetting, but I will chance that and choose subject matter that would make that less of an issue. Thanks in advance.