The lens is about the same size as an older Nikkor 50mm F1.4. With the provided sunshade, it obstructs about the lower-right 1/8th of the 35mm framelines. This often happens with fast RF lenses, I am used to the Canon 50/0.95 obstructing about 1/3rd of the viewfinder on the Canon 7. in practice, it is not as much of a problem as it would be with an SLR.The RF shows you what is around the field of view of the lens. In the case of a lens that obstructs view, move the camera around a bit to compose. Basically build a mental image of the missing segment.