Infrared photography

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Tree example IR.jpg Tree example VIS.jpg

Top: tree photographed in the near infrared range. Bottom: same tree in the visible part of the spectrum.

Infrared image of the Mississippi River crossed by a bridge and a dam, between red foliage on left, and blue parking lots and buildings on right
Visible vs. Infrared (900 nm LP) Aerial Photography of Old Hickory Lake, Tennessee. Taken from a passenger airplane within seconds apart using SONY H-9 Digital camera.





Until the early 20th century, infrared photography was not possible because silver halide emulsions are not sensitive to longer wavelengths than that of blue light (and to a lesser extent, green light) without the addition of a dye to act as a color sensitizer.[2] The first infrared photographs (as distinct from spectrographs) to be published appeared in the February 1910 edition of The Century Magazine and in the October 1910 edition of the Royal Photographic Society Journal to illustrate papers by Robert W. Wood, who discovered the unusual effects that now bear his name.[3][4][5] The RPS co-ordinated events to celebrate the centenary of this event in 2010.[6] Wood's photographs were taken on experimental film that required very long exposures; thus, most of his work focused on landscapes. A further set of infrared landscapes taken by Wood in Italy in 1911 used plates provided for him by CEK Mees at Wratten & Wainwright. Mees also took a few infrared photographs in Portugal in 1910, which are now in the Kodak archives.

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.[7] After 1930, new emulsions from Kodak and other manufacturers became useful to infrared astronomy.[8]




A near-infrared photograph of a Ringling Brothers' train idling near MIT in Cambridge, Massachusetts


Focusing infrared[edit]




Some lens manufacturers such as Leica never put IR index marks on their lenses. The reason for this is that 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[edit]

Infrared negatives fogged by the frame counter of a Minolta Maxxum 4.
View of the Hollywood Hills. Kodak Infrared color slide film, 35mm manual focus Nikkon lens no filter used and developed with E-6 process.



Black-and-white infrared film[edit]






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 least 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[needs update] with good sensitivity beyond 750 nm, the Rollei film does extend beyond 750 nm but IR sensitivity falls off very rapidly.

Color infrared film[edit]

Kodak Ektachrome Infrared Color 35mm Color Film (Expired: 1970's)
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.[14] 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 says 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.




Kodak 35mm color infrared film has been discontinued; A Los Angeles photographer named Dean Bennici is the last person to offer color infrared film to the public, introducing Aerochrome Infrared to the global market in 2008. He personally cut and hand rolled all Aerochrome film which exists today and is responsible for its revival and relevance in contemporary photography. [15]

Digital cameras[edit]

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,[16] which would interfere with the normal photography by confusing the autofocus calculations or softening the image (because infrared light is focused differently from 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.[17] Thus, to improve image quality and protect privacy, many digital cameras employ infrared blockers.[18] 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 and not for IR.

An example of color digital infrared photography. The camera's infrared blocking filter has been removed. Red and blue channels have been swapped for more conventional sky color.

An alternative method of DSLR infrared photography is to remove the infrared blocker in front of the sensor 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.[19] 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.[20]


A Nikau palm against a clear, sunny sky shows the high contrast that is often typical of outdoors infrared photography.


Another common technique with near infrared filters is to swap blue and red channels in software (e.g. photoshop) which retains much of the characteristic 'white foliage' while rendering skies a glorious blue.

Nightshot infrared photography of a stove with 600 nm red-filter and polarizing filter at daylight.

Several Sony cameras had the so-called Night Shot facility, which physically moves the blocking filter away from the light path, which makes the cameras very sensitive to infrared light. Soon after its development, this facility was 'restricted' by Sony to make it difficult for people to take photos that saw through clothing.[17] To do this the iris is opened fully and exposure duration is limited to long times of more than 1/30 second or so. It is possible to shoot infrared but neutral density filters must be used to reduce the camera's sensitivity and the long exposure times mean that care must be taken to avoid camera-shake artifacts.

The reverse of the United States five-dollar bill has two rectangular strips that are blanked out when viewed in the infrared spectrum, as seen in this image taken by an infrared camera.



Thermographic image of coffee cup


See also[edit]

Digital infrared using a 50mm lens, D810 and the program Exposure. Infrared photography typically produces false-color artifacts, such as turning greens into pinks and purples as shown in this example.


  1. ^ The Wood Effect results from the transparency of chlorophyll at wavelengths over 500 nm allowing light to be reflected within the plant cells. Normally the effect is invisible because so much green light is reflected by the foliage but it is possible to see the effect, albeit dimly, with the naked eye by looking through a 720 nm filter (or similar) on a sunny day and allowing your eye to adjust to the low light.
  2. ^ "Chemistry of Photography". Retrieved 2006-11-28. 
  3. ^ Robert W. Wood (February 1910). "A New Departure in Photography". The Century Magazine. The Century Company. 79 (4): 565–572. 
  4. ^ Robert W. Wood (October 1910). "Photography By Invisible Rays". The Photographic Journal. Royal Photographic Society. 50 (10): 329–338. 
  5. ^ "Pioneers of Invisible Radiation Photography – Professor Robert Williams Wood". Archived from the original on 2006-11-12. Retrieved 2006-11-28. 
  6. ^ "100 Years of Infrared". The RPS Journal. Royal Photographic Society. 148 (10): 571. Dec 2008 – Jan 2009. 
  7. ^ Annual Report of the Director Bureau of Standards to the Secretary of Commerce for the Fiscal Year Ended June 30, 1919 U. S. Govt. Print. Off., United States National Bureau of Standards, pp. 115–119, 1919.
  8. ^ Harvard paper, 1932 Early Infrared astronomy
  9. ^ Walter Clark (1939). Photography by infrared: its Principles and Applications. Wiley. 
  10. ^ American Cinematographer 1941 Vol 22
  11. ^ This is because HIE lacks anti-halation layers and has a completely transparent base rather than being directly due to infrared sensitivity. Film usually has a slightly fogged base and anti-halation layers coated on it in order to stop light bouncing around in the substrate once the image has been taken. Light can enter film through the tail protruding from a 35mm canister and without a fogged base it will be piped into the film and expose it. Without an anti-halation layer any light entering the substrate through the emulsion will be reflected back and forth inside the film, becoming diffuse as it travels and causing halation. HIE lacked a fogged base and anti-halation layers for two reasons: sensitivity is increased by allowing light to reflect back and forth and it was difficult to find any way of treating the film that would be effective at infrared wavelengths.
  12. ^ Kodak, Discontinuance notice
  13. ^ "Due to declining demand, KODAK High-Speed Infrared Film / HIE has been discontinued, effective YE 2007."; Kodak, [1]
  14. ^ Applied Infrared Photography. M–28 (1972 ed.). Kodak Publications. pp. 4–5. 
  15. ^ [2]
  16. ^
  17. ^ a b "Ultra-Personal Sony Handycam" (Press release). Reuters wire service. 1998-08-12. Retrieved 2007-02-09. 
  18. ^ Spectral curves of RGB and Hot Mirror filters.
  19. ^ Digital Infrared at Jim Chen Photography
  20. ^ Examples of colors achieved with digital infrared photography.
  21. ^ IS-1 web page including EULA

External links[edit]