I have had a couple of old fast bits of glass for a few years now, and I just added a 135mm f2.8 Tamron to the pack. So at 24mm f2.8, 50mm f1.4 and 135mm f2.8 it is a pretty decent range for general work. Nothing to wide or long. Based on a test I did some time ago, I had always assumed that the 50mm was the sharpest thing in the bag, even wide open. This morning I put them all to the test, comparing them to the new Sigma 18-200. Tripod mounting, 2 second mirror lockup etc were all used to help reduce shake. The subject was the branches in the back garden on an overcast day. It was not a happy test, especially for the fast 50! At all settings the new Sigma trounced the old (except that it could not compete with f1.4 or f2.8), clearer and better contrast. Most of the problems are in relation to flare, especially wide open in the 50. The Tamron suffers from purple aberrations (not even fringing, which could be corrected) which is to be expected as I don’t think it has any aspherical elements seen in newer designs. The Sigma 24mm is the better of the bunch, not surprising as it is the newer as well. I am still keeping them all for low light work and I might get around to trying them out under those circumstances when I have recovered from this.