K&F CONCEPT offers matte boxes that come with ND filters (ND4, ND8, ND16, ND32, ND64), which feature a low reflectivity of just 0.2%, effectively minimizing lens flare and ghosting.
The Zoomar is coated, but not multi-coated, but still delivers a good performance in terms of lack of flare. Generally, the lens ... 1 stop. At 82mm we have a huge -4.5 stops of darkening at f/2.8 ...