Hey. I just received my new tamron 28-75mm 2.8 lens and it shoots very pretty footage from what I can tell thus far. One thing I was curious about though is that when i change the aperture it makes a rather audible clicking noise that is certainly louder and more notched sounding than my kit lens that came with my 7D. Is this normal? Just want to make sure it isnt a sign of a defect of some sort. I simply don't have much any experience with non-canon lenses prior to this, and I was curious if this was normal. Thanks!