After only a few months of use, my 150-600 has accumulated far more dust behind the front element than my 100-400 did over 1.5 years of use. I knew it would accumulate dust, but this is far beyond any amount I would reasonably expect. Any other early adopters have this issue?
I blew the dust off the front element before taking this pictures, thus most of the spots you see are internal.
I've had my lens since the middle of Febraury and use it almost daily. The insides are spotless. Sorry for your lenses condition My 100-400mm was spotless too after 4 years. I've often thought the high humidity in Florida reduces the issues with dust. A friend in Phoenix has huge issues with dust on sensors and in several lenses.
I have the same issue. Mine looks almost identical to your picture. As far as I can tell it does not have any effect on image quality. It is irritating to look at.
Ronthemon wrote:
I have the same issue. Mine looks almost identical to your picture. As far as I can tell it does not have any effect on image quality. It is irritating to look at.
But if the dust keeps building up at this rate, it will eventually affect your images.
We've had to dust them a bit already. Not as bad as the new Nikon 80-400 VR and Canon 17-55, which are the dust champions, but we've had to dust out several of the 150-600s already, so looks to be on the 'dust accumulater' side of the equation.
Tamron does a quick turnaround on 'clean and check' if the dust gets heavy. I can post how to dust it yourself, but it would void your warranty so I wouldn't recommend it until the warranty period is up.
I'd suspect that the location and usage has a big affect on dust. I have never had a issue with dust in any of my lenses, not a speck. Not in the 17-55 or the 100-400, or any others. I usually don't go out in dusty conditions, and we do have some huge dust storms up here.
My 100-400mm was spotless too after 4 years. I've often thought the high humidity in Florida reduces the issues with dust. A friend in Phoenix has huge issues with dust on sensors and in several lenses. 
