Hello everyone! I am looking for a 50mm f:1.4, and I have seen that there are several versions. I have seen that there are several versions of this lens. According to the subjective evaluation of David Ruether, the AIS model is better optically than the non AI. I assume that optically there is no difference between the AI and the AIS model. My worry is how can I distinguish a 50mm AI from a 50mm non-AI (to distinguish AIS is quite easy). Can someone tell me how could differentiate these models, and if he/she agrees with David Ruether on that the AIS is better optically..... Another question is about an old 35-70 f3.5 zoom I have. This zoom is AI, and it has 72mm of filter diameter. I read a very nice article by Foo Leonard where he states that a 35-70 f3.5 zoom AIS and 62mm diameter for filters was very good. This made me wonder about my zoom..... Has anyone any experience or knowledge about my lens?? I would appreciate any feedback Thank you very much Marc
