Hoya started out in 1941 in Tokyo as a global med-tech and technology company and is presently the world’s largest supplier of optical glass, with approximately 50% of the market share for optical glass production. It should know a thing or two when it comes to creating quality filters for photography, then. I got hold of a Hoya R72 infrared filter, which is designed to block visible light and only allow a narrow band of infrared light into the camera, with wavelengths between 760 and 860nm.
The Hoya R72 can be used on standard cameras for an infrared long-exposure effect, where the light-blocking properties of the R72 lengthen the exposure time by up to several minutes, because the sensor already has an IR cut filter installed that makes it not very sensitive to IR wavelengths; however, the resulting red-tinged image has to be converted to black and white.
