The Lens Stress Tester is used to determine the condition of a lens so you can quickly decide if it needs to be replaced. If the lens is damaged by thermal stress, the shape of a cross appears in the lens when the polarized film is rotated.
The Lens Stress Tester is used to determine the condition of a lens so you can quickly decide if it needs to be replaced. If the lens is damaged by thermal stress, the shape of a cross appears in the lens when the polarized film is rotated.