This is the type of flare you can expect from the CONTAX Zeiss 28mm f2.8 if you point it directly at the sun. This photo is somewhat underexposed to show more detail around the sun and the character of the sun-stars this lens produces. It will flare more than a modern Nikon or Zeiss lens.
A hood will help from light coming in from an angle, but not these direct shots of the sun.