<p>I just bought a nice looking copy of 12-40 lens off ebay. My question is: when looking at the lens and zooming<br> down, the barrel seems to bottom out at around 16mm then creeps forward a bit when I get to 12mm. Is this a normal function? Looking thru the lens all seems fine. Just seems a little odd to me. Just getting to try some shots tomorrow with the lens. any help will be appreciated. Thanks</p>