Lens extension and retraction. Operation of the internal aperture blades. The above have been confirmed. There is a coating deterioration on the lens, or some kind of stain that I'm not sure about. The "CONTAX" option was not available in the mount selection, so I have selected "NIKON F mount," but it is a lens for a CONTAX camera. ※ Please note that this is a used item, and I do not have the specialized knowledge of a camera store. Therefore, there may be oversights. Please assume that anything not mentioned has not been confirmed. We cannot provide support or warranty for any changes in condition or malfunctions after receipt. Please purchase only if you agree to these terms. Returns are not accepted as this is a used item.