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The majority of black-and-white infrared art, landscape, and wedding photography is done using orange (Wratten #15 or 21), red (#23, 25, or 29) or visually opaque (#72) [d] filters over the lens to block the blue visible light from the exposure. Very dark-red (#29) filters block out almost all blue, and visually opaque (#70, 89b, 87c, 72 ...
When infrared light of these frequencies strikes an object, the energy is reflected or transmitted. If the object is transparent, then the light waves are passed on to neighboring atoms through the bulk of the material and re-emitted on the opposite side of the object. Such frequencies of light waves are said to be transmitted. [10] [11]
Infrared communications are useful for indoor use in areas of high population density. IR does not penetrate walls and so does not interfere with other devices in adjoining rooms. Infrared is the most common way for remote controls to command appliances. Infrared remote control protocols like RC-5, SIRC, are used to communicate with infrared.
In some cases, underdrawing can be clearly visualized using infrared reflectography because carbon black pigments absorb infrared light, whereas opaque pigments such as lead white are transparent with infrared light.
Infrared sensitive high-speed film with moderately high contrast, sensitive to light and radiant energy to 900 nanometres (nm). It is useful for haze penetration and for special effects in commercial, architectural, fine art, and landscape photography.
For instance, some kinds of glass, while transparent in the visual range, are largely opaque to ultraviolet light. More extreme frequency-dependence is visible in the absorption lines of cold gases. Opacity can be quantified in many ways; for example, see the article mathematical descriptions of opacity.
Conventional personal cooling is typically achieved through heat conduction and convection. However, the human body is a very efficient emitter of infrared radiation, which provides an additional cooling mechanism. Most conventional fabrics are opaque to infrared radiation and block thermal emission from the body to the environment.
Infrared cut-off filters, sometimes called IR filters or heat-absorbing filters, are designed to reflect or block near-infrared wavelengths while passing visible light. They are often used in devices with bright incandescent light bulbs (such as slide and overhead projectors ) to prevent unwanted heating.