突然明白了，原來5D3不貴呀。

Instead of buying last generation camera with 16-35 f/2.8, 24-70 f/2.8L (no IS), 70-200 f/2.8L IS, you can do better with 5D3 with 17-40 f/4, 24-105 f/4L IS and 70-200 f/4L IS in terms of shutter speed and ISO noise at lower cost. Plus this package is significantly lighter, thus more portable.