jodelak wrote in post #16650579
hi eric, if i may ask a question, say after a few months of using the tamron and you are comfortable with it, and on 1 particular birding day you saw a bird that is a lifer for you, and it is on a distance that is within the 100-400 reach. would you put the canon 100-400? or the tamron 150-600?

Peter's most likely right; I would use whichever one was easiest to get the bird framed with. Right now, if neither one were currently mounted and I was having to choose on the fly, I'd grab the Canon; but, assuming that I find my comfort zone with the Tamron and get any bugs worked out of the system, I'd probably grab the Tammy.
I keep recalling back to the first two months that I had the Canon, years ago. I was absolutely convinced that the design was wonky, that it couldn't be shot in anything less than broad daylight and that there was no way I'd continue to use it. Now, it's my favorite lens to use and it'll be a cold day in hell before it leaves my possession, regardless of the other guns in the cabinet.
So, if I was so certain of that lenses "defects" and "problems" back then, who's to say that I won't feel the same about this lens in 12mo or so? There are some hiccups with it that mean I'll probably have to send it in to Tamron for a checkup, just to be certain, but I've done that with just about every piece of gear that I currently own anyway. <shrug> If there's something legitimately wonky (as appears to be the case with Jason's lens), it would be a shame to write off such a good tool, completely, for something that a tech in a lab can tweak and fix.