1. when choosing 24-105 and 17-55, do not even think about taking 17-55! - it is better in many ways (2.8, focusing speed and tenacity, it is better and faster to sell used) 2. after purchase, immediately take a normal protective filter, as a good option Hoya HD Protect 77 mm. (Do not take UV - this is a waste of money, better save it for future expenses;))) 3. IMHO 17-40 and 24-105 is a way out of the situation with the difficulty of buying 24-70 for FF owners. A 17-55 mm. this is the best of all the worst and average! CONCLUSION: Live in the present! When you have funds for Marc III, then 24-70 2.8 and other worthy lenses of the L series will not be a problem for you. With respect to all who helped - happy owner 17-55 ;) One year later: I confirm all of the above. PS: buy used in excellent condition. For a price of 23-25 thousand. And you will be happy. If you have questions write, I know I will prompt. And let everything bought bring you only joy !