Hi xtentpegx, welcome to the Sony Forums

With a couple of exceptions, the LA-AE1 adaptor will only auto-focus properly with a-mount SSM and SAM lenses. Some Sigmas are ok, others (even Sony a-mounters) will only work very slowly, due to the use of contrast-detection AF.

Your Tamron should manually focus and work ok in every other respect, but you'll need the LA-AE2 adaptor, which adds phase-detection AF, to get functoinal AF with that lens on the NEX-5. It's unfortunately a bit more expensive, but if you just bought it new hopefully you'll be able to exchange for the AE2?

Cheers

Mick