History Until the early 1900s infrared photography was not possible because silver halide emulsions are not sensitive to infrared radiation without the addition of a dye to act as a color sensitizer The first infrared photographs to be published appeared in the October 1910 edition of the Royal Photographic Society Journal to illustrate a paper by Robert W Wood who discovered the unusual effects that now bear his name The RPS is co ordinating events to celebrate the centenary of this event in 2010 Wood s photographs were taken on experimental film that required very long exposures thus most of his work focused on landscapes Infrared sensitive photographic plates were developed in the United States during World War I for spectroscopic analysis and infrared sensitizing dyes were investigated for improved haze penetration in aerial photography Infrared photography became popular with photography enthusiasts in the 1930s when suitable film was introduced commercially The Times regularly published landscape and aerial photographs taken by their staff photographers using Ilford infrared film By 1937 33 kinds of infrared film were available from five manufacturers including Agfa Kodak and Ilford Infrared movie film also available and was used to create day for night effects in motion pictures a notable example being the pseudo night aerial sequences in the James Cagney Bette Davis movie The Bride Came COD False color infrared photography became widely practiced with the introduction of Kodak Ektachrome Infrared Aero Film and Ektachrome Infrared EIR The first version of this known as Kodacolor Aero Reversal Film was developed by Clark and others at the Kodak for camouflage detection in the 1940s The film became more widely available in 35mm form in the 1960s but KODAK AEROCHROME III Infrared Film 1443 is their sole remaining infrared film Infrared photography became popular with a number of 1960s recording artists because of the unusual results Jimi Hendrix Donovan Frank Zappa and the Grateful Dead all issued albums with infrared cover photos The unexpected colors and effects that infrared film can produce fit well with the psychedelic aesthetic that emerged in the late 1960s For some infrared photography can easily look gimmicky but many photographers such as Elio Ciol and Martin Reeves have made subtle use of black and white infrared sensitive film With the advent of digital infrared photography as a part of full spectrum photography the technique is gaining popularity and is being sold as fine art photographs in a variety of galleries worldwide A near infrared photograph of a Ringling Brothers train idling near MIT in Cambridge Massachusetts Infrared light lies between the visible and microwave portions of the electromagnetic spectrum Infrared light has a range of wavelengths just like visible light has wavelengths that range from red light to violet Near infrared light is closest in wavelength to visible light and f ar infrared is closer to the microwave region of the electromagnetic spectrum The longer far infrared wavelengths are about the size of a pin head and the shorter near infrared ones are the size of cells or are microscopic Focusing infrared Infrared filters Most manual focus 35 mm SLR and medium format SLR lenses have a red dot line or diamond often with a red R called the infrared index mark that can be used to achieve proper infrared focus many autofocus lenses no longer have this mark When a single lens reflex SLR camera is fitted with a filter that is opaque to visible light the reflex system becomes useless for both framing and focusing one must compose the picture without the filter and then attach the filter This requires the use of a tripod to prevent the composition from changing A sharp infrared photograph can be done with a tripod a narrow aperture like f 22 and a slow shutter speed without focus compensation however wider apertures like f 2 0 can produce sharp ph otos only if the lens is meticulously refocused to the infrared index mark and only if this index mark is the correct one for the filter and film in use However it should be noted that diffraction effects inside a camera are greater at infrared wavelengths so that stopping down the lens too far may actually reduce sharpness Most apochromatic APO lenses do not have an Infrared index mark and do not need to be refocused for the infrared spectrum because they are already optically corrected into the near infrared spectrum Catadioptric lenses do not require this adjustment because mirrors do not suffer from chromatic aberration Zoom lenses may scatter more light through their more complicated optical systems than prime lenses that is lenses of fixed focal length for example an infrared photo taken with a 50 mm prime lens may look more contrasty than the same image taken at 50 mm with a 2880 zoom Some lens manufacturers such as Leica never put IR index marks on their lenses The r eason for this is because any index mark is only valid for one particular IR filter and film combination and may lead to user error Even when using lenses with index marks focus testing is advisable as there may be a large difference between the index mark and the subject plane Film cameras Infrared negatives fogged by the frame counter of a Minolta Maxxum 4 Many conventional cameras can be used for infrared photography where infrared is taken to mean light of a wavelength only slightly longer than that of visible light Photography of rather longer wavelengths is normally termed thermography and requires special equipment With some patience and ingenuity most film cameras can be used However some cameras of the 1990s that used 35mm film have infrared sprocket hole sensors that can fog infrared film their manuals may warn against the use of infrared film for this reason Other film cameras are not completely opaque to infrared light Black and white infrared film Black and whit e infrared negative films are sensitive to wavelengths in the 700 to 900 nm near infrared spectrum and most also have a sensitivity to blue light wavelengths The notable halation effect or glow often seen in the highlights of infrared photographs is an artifact of Kodak High Speed Infrared HIE black and white negative film and not an artifact of infrared light The glow or blooming is caused by the absence of an anti halation layer on the back side of Kodak HIE film this results in a scattering or blooming around the highlights that would usually be absorbed by the anti halation layer in conventional films Frank Lloyd Wright s Rudin House panchromatic film on the left infrared on the right The majority of black and white infrared art landscape and wedding photography is done using orange 15 or 21 red 23 25 or 29 or visually opaque 72 filters over the lens to block the blue visible light from the exposure The intent of filters in black and white infrared photography is to bloc k blue wavelengths and allow infrared to pass through Without filters infrared negative films look much like conventional negative films because the blue sensitivity lowers the contrast and effectively counteracts the infrared look of the film Some photographers use orange or red filters to allow slight amounts of blue wavelengths to reach the film and thus lower the contrast Very dark red 29 filters block out almost all blue and visually opaque 70 89b 87c 72 filters block out all blue and also visible red wavelengths resulting in a more pure infrared photo that usually looks more contrasty Certain infrared sensitive films like Kodak HIE must only be loaded and unloaded in total darkness Infrared black and white films require special development times but development is usually achieved with standard black and white film developers and chemicals like D 76 Kodak HIE film has a polyester film base that is very stable but extremely easy to scratch therefore special care must be used in the handling of Kodak HIE throughout the development and printing scanning process to avoid damage to the film As of November 2 2007 KODAK is preannouncing the discontinuance of HIE Infrared 35 mm film stating the reasons that Demand for these products has been declining significantly in recent years and it is no longer practical to continue to manufacture given the low volume the age of the product formulations and the complexity of the processes involved At the time of this notice HIE Infrared 135 36 was available at a street price of around 12 00 a roll at US mail order outlets Arguably the greatest obstacle to infrared film photography has been the increasing difficulty of obtaining infrared sensitive film However despite the discontinuance of HIE other newer infrared sensitive emulsions from EFKE ROLLEI and ILFORD are still available but these formulations have differing sensitivity and specifications from the venerable KODAK HIE that has been around for at lea st two decades Some of these infrared films are available in 120 and larger formats as well as 35 mm which adds flexibility to their application With the discontinuance of Kodak HIE Efke s IR820 film has become the only IR film on the market with good sensitivity beyond 750 nm the Rollei film does extend beyond 750 nm but IR sensitivity falls off very rapidly Color infrared film An example of color infrared Color infrared transparency films have three sensitized layers that because of the way the dyes are coupled to these layers reproduce infrared as red red as green and green as blue All three layers are sensitive to blue so the film must be used with a yellow filter since this will block blue light but allow the remaining colors to reach the film The health of foliage can be determined from the relative strengths of green and infrared light reflected this shows in color infrared as a shift from red healthy towards magenta unhealthy Early color infrared films were developed in the older E 4 process but Kodak later manufactured a color transparency film that could be developed in standard E 6 chemistry although more accurate results were obtained by developing using the AR 5 process In general color infrared does not need to be loaded in total darkness despite what it said on the can or refocused to the infrared index mark on the lens In 2007 Kodak announced that production of the 35 mm version of their color infrared film Ektachrome Professional Infrared EIR would cease as there was insufficient demand It is assumed that the 70 mm Aerographic format will continue There is no currently available digital camera that will produce the same results as Kodak color infrared film although the equivalent images can be produced by taking two exposures one infrared and the other full color and combining in post production The color images produced by digital stills cameras using infrared pass filters are not equivalent to those produced on color infrared film The colors result from varying amounts of infrared passing through the color filters on the photo sites further amended by the Bayer filtering While this makes such images unsuitable for the kind of applications for which the film was used such as remote sensing of plant health the resulting color tonality has proved popular artistically Color digital infrared as part of full spectrum photography is gaining popularity The ease of creating a softly colored photo with infrared characteristics has found interest among hobbyists and professionals with art work being sold in galleries since 2005 Availability Kodak color infrared film for 35 mm has been discontinued It is still available in 120 medium format from a supplier in Germany who cuts it down from fresh bulk stock Otherwise there is no known supplier of fresh stock The 35 mm rolls that are still available on various sites are for the most part expired Digital cameras Bending Cypress infrared shot by Sigma SD10 with B W 093 filter ISO 100 f 8 1 160 s Digital camera sensors are inherently sensitive to infrared light which would interfere with the normal photography by confusing the autofocus calculations or softening the image because infrared light is focused differently than visible light or oversaturating the red channel Also some clothing is transparent in the infrared leading to unintended at least to the manufacturer uses of video cameras Thus to improve image quality and protect privacy many digital cameras employ infrared blockers Depending on the subject matter infrared photography may not be practical with these cameras because the exposure times become overly long often in the range of 30 seconds creating noise and motion blur in the final image However for some subject matter the long exposure does not matter or the motion blur effects actually add to the image Some lenses will also show a hot spot in the centre of the image as their coatings are optimised for visible light a nd not for IR An alternative method of DSLR infrared photography is to remove the infrared blocker in front of the charge coupled device and replace it with a filter that removes visible light This filter is behind the mirror so the camera can be used normally handheld normal shutter speeds normal composition through the viewfinder and focus all work like a normal camera Metering works but is not always accurate because of the difference between visible and infrared reflection When the IR blocker is removed many lenses which did display a hotspot cease to do so and become perfectly usable for infrared photography Additionally because the red green and blue micro filters remain and have transmissions not only in their respective color but also in the infrared enhanced infrared color may be recorded Since the Bayer filters in most digital cameras absorb a significant fraction of the infrared light these cameras are sometimes not very sensitive as infrared cameras and can somet imes produce false colors in the images An alternative approach is to use a Foveon X3 sensor which does not have absorptive filters on it the Sigma SD10 DSL
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