Hello, I've read a few lens reviews that claim professional photographers dont use mid-range zooms. At the same time I have been interested in getting the Sigma 24-70 F2.8 to replace my kit lens. I thought this would be a helpful addition to my gear as I will be mainly shooting travel/street photography. As of right now I have a 50mm 1.4 prime, 12-24 wide angle, and telephoto. I love my 50mm but am concerned that I may want more depth of field and flexibility. What is your opinion about adding a good midrange zoom? What do you do? Thanks for your thoughts!