The flash is a great addition to this lens and together they produce some amazing quality images. I have only opened the 58mm as that is the size that fits the MP-E. You also have a 52mm, 67mm and 72mm.
YN50mm F1.8, it's the first prime lens produced by Yongnuo, it suports AF Auto Focus function, and MF manual Focus function. A great prime lens that is an excellent addition to the EOS 18-55mm lens kits. Provides much faster aperture for low light usage and has better edge to edge sharpness. Also works well with cameras such as the 5D, 7D, 60D, 70D, T3, T3i, T5, T5i, plus more.