Actually I have a 55/3.5 -- I thought it was another 2.8. BUT...even though it is beautiful (looks like new except for a fingerprint of the inside glass), it will not meter on the cameras (so it might be modified for slide copier it was pulled off of). The back where it attaches to the body is slightly different than the 55/2.8 Nikon lens.

The aperature does close down properly when the shutter is fired.

I suppose it can be used with an external meter, but I do not know how much to compensate for "bellow factor" -- or if one even has to (my experience is with ones that can meter thru the lens, and LF cameras where I can measure the bellows draw)