Even though the sun has an angular diameter of half a degree in the sky, the shadow of this window screen on a wall 5 meters away isn't totally blurred out — the horizontal lines of the mesh are still visible!
My guess is that this is because the sun's shining between some trees' leaves — since most (but not all) of the sun's covered by the leaves, the window screen shadow acts as if the light source had a smaller angular diameter. Or maybe it's not so much the angular diameter that matters — the disk of the sun acts like a blur kernel, so if random parts of it are covered, it'll attenuate higher frequencies (like in the window screen pattern) less.
