6.6" x 6.6" Clear Filter - Lindsey Optics Brilliant Clear Filters are designed to protect expensive cine lenses while maintain image quality. They will not introduce distortions, color shifts or focus shift. The are made from the finest optical glass and are ground and polished flat to ensure sharp images. The flatness of our filters is tested on our Zygo phase shift interferometer. Every filter has a 7 layer broadband anti-reflection coating on both sides. Our coatings are extremely durable.