Do lenses lose sharpness as they age?
Several years ago, I had purchased a EF 75-300mm f/4.5-5.6 IS USM.
(That was before I joined this forum and knew better).
When the lens was new, I did some test shots at 300mm and was happy with the results -- I was able to see good feather detail on the ducks! I had also gotten some nice shots of my kids playing soccer and little league.
But now it seems that unless I am shooting at about 90mm and f/8 -- I cannot get any sharp images with this lens. I have never dropped this lens or abused it. The glass is clean. About the worst incidents that I can think of is a few times, when pulling it from the bag, the lens extended as I pulled it out.
It has gotten to the point that I don't even want to use this lens. Upgrading to one of the Ls is not currently an option.