The lens features a big, convex element at the front which is sheltered from side light by the built-in petal type hood. The problem is that with such angles of view a hood must be small in order not to obscure the edges of the frame. As a result already at first glance you can notice that this hood is definitely too short to perform well its basic function.
When we add to it a big number of elements so a lot of air-to-glass surfaces which can reflect the light, we get a recipe for troubles. The troubles are indeed huge which can be seen in the photos below. Flares appear at all focal lengths and throughout the whole range of apertures.
