I am sure the AIS version is really good too. I think they changed the optical formula but I could be wrong. The AI copy I have kills it. Got it for $179 bucks and it was the best money I have ever spent. I would think the ais version is the same but I have not tried it, so I can't speak for it. There is something magical in that lens, something that just is not in modern glass. I am a big fan of ai and ais lens, so I am partial to them but I have my share of modern lenses too and there is something dreamy and special about the old 105's. I highly recommend getting one. I would love to try out the AIS version. I have the 105mm 2.8 micro ais and it is my favorite macro/micro lens by far. Old pro glass is hard to beat, unless you can't hang with manual focus. There is a time and place for manual and a time and place for mandatory autofocus but when I get the chance I almost always work in a few shots with my trusty 105mm 2.5 ai and shoot it around f/4 to f/5.6 and get the subject to be a distance from the background and whammo, the best bokeh ever. I like to shoot it at f/2.5 because it gives a dreamy look but for face portraits, it is not enough DOF to get the nose to ear focus plane sharp. I also like to use the 105mm 2.5 ai for flower portraits but usually the 105 2.8 ais micro jumps in there during that application.