Hi, I have seen the usage of GND in taking sunset pictures where the top half is usually brighter than the bottom half. Would the GND just as effective if I were to use it in a diagonal manner? For example, a scene where the right half is brightly lit from the middle top to the bottom right. Since I already has a clear multi-coated filter on my lense and I plan to mount the GND on top of the clear filter. Do I still need a multi-coated one? Thanks.