138mm Letterbox Diopter Strength:1 It creates a darkening of

It creates a darkening of the entire image

Two-year warranty against manufacturing defects

The light from the sun naturally becomes partially polarized due to reflecting off electrons in air molecules

the effects of infrared pollution become more apparent

near-infrared light waves beginning at 680nm are blocked by approximately 45%

138mm Letterbox Diopter Strength:1 It creates a darkening ofLetter Box Diopters are considered the reverse of the Strip Diopters. An open slot in the center (similar to a slot in a mail letter box) is flanked by diopter glass on either side. These diopters allow you to create interesting effects while experimenting and allow you to achieve varied focus, diffusion and double imaging effects. They come in 15mm and 30mm formats.