Hi, I'm the lucky new owner of both the 12-35, and 35-100 f/2.8's. The 12-35 was picked up off craigslist in good condition- some light scratches from normal use. The 35-100 is new. The focus ring on the 12-35 is much stiffer than the 35-100. Is this normal? The only thing I could think of is it's stiffer as to not get confused with the zoom ring which is smaller and similar in size. thanks!