I bought this lens about a month ago that turned out to have some problems (couldn't focus farther than about 20 feet, soft in weird ways etc) so I returned to the seller. He took it to a repair shop and asked me if I wanted to give it another try and I said yes. Apparently, they fixed the focusing and infinity is there now. Sharpness is another story, but it's definitely much better than before. But I noticed something I don't remember noticing in any other lens I've had (never had a macro, I know they do this): while focusing, the magnification changes albeit very slightly. Is this even possible with properly functioning prime lens or is it just another sign that there is still something wrong with it? I've had about 20 primes and can't for the life of me remember seeing anything like that.