Do not, under any circumstances, miss Cades Cove!
There's a photo opp EVERYWHERE you look!
Google "Lally Cap" they are cheap and work just as well as anything else.
sorry to hear your tale of woe, I just got the Sigma 150-500 and am as happy as a dead pig in the sunshine with mine.
Tamron 18-270! it's a great all around lens. A bit slow but you can up your ISO. On a 1.6 crop factor camera it's 432mm on the high end of zoom
I have a Tamron 18-270mm that pretty much stays on my camera.
Put your lens on man.focus and set it to infinity (canons infinity mark is not right) or just a little short of the mark. The best thing to do is set focus on something while there's still enough light to see it, then leave it alone.
I mean as wide open as lens will allow. Lowest number...F2.8 usually.
App priority @ lowest Fstop your lens will allow. ISO 100. spot metering. 1 stop underexposed. Mirror locked up. cable release.