After making the purchase, I did some testing with tables right away and arrived to the following conclusions: 1) It does not wash the edges of the frame; rather, they are just darker (also known as vignetting), which lowers the clarity of the image near the edges when saved as a jpeg. 2) I can vouch for the fact that the aperture of the lens 50/1.4 F4 is equivalent to the aperture of the 24-105/4 F4.5, which means that he is darker. My copy of the lens is sharp at F4, and as the aperture is decreased, the quality of the picture only improves at the lens's edges. In general, the lens is good and produces high-quality pictures during the day. I pair it with a 5D Mark II.