So I've been increasingly disappointed with my Tamron 28-70 f/2.8. It's a little soft at 5.6, and really soft wider than that. I'd like to upgrade to the Canon 24-70 f/2.8, but that's pricey and heavy. I've been looking at the 28-105 f/4 IS. The price is more palatable, and it has IS, but it's a little slower. So now I'm thinking about a combo of primes. I have the 50 f/1.8. I'm thinking about adding a telephoto and a wide angle. Maybe the 100 f/2.0 and the 24 f/2.8? Any thoughts? Am I going to hate switching lenses all the time? Will it always seem that I have the wrong lens on the camera, just out of pure Murphy's Law? btw, I shoot with a 50D, and I'm really still learning, so I do a lot of walking around and shooting. Birds, amateur sporting events, flowers, street shots, swamps, the ocean, anything that crosses my path.