Insect infrared reflectance

In the previous post I wrote about the work of Tristán and Michaud in Costa Rica and their papers from the early 1910s on infrared. They were somewhat prolific with their infrared research, including a paper on the appearance of soils, skin and insects over the next few years.

I had been searching for a copy of the article they published in Scientific American on how insects, especially butterflies, look in infrared. Very kindly Michael Mielewczik from the Institut für Agrarwissenschaften (agricultural science) in Zurich sent me not only a scan of the SciAm pages but also a paper he co-wrote on a very similar subject.

Tristan and Michaud had black and white infrared film to work with but Michael and his colleagues have made good use of a digital camera with no infrared blocking and bandwidth-limited to 675-800 nm (deep red/near infrared). The resulting colour palette, presumably due to the optical properties of the beyer filtration on the sensor, is mostly red/magenta. A photograph of a green tree python is particularly striking but the paper really concentrates on insects. Here's an example image showing visible and infrared reflectance characteristics of a group of preserved rose chafer Caelorrhina superba beetles.

The different infrared tones can be clearly seen (B).

The full citation of the paper is:

Mielewczik M, Liebisch F, Walter A, Greven H (2012) Near-Infrared (NIR)-Reflectance in Insects - Phenetic Studies of 181 Species. Entomologie heute 24:183-215

... and you can access the paper as a PDF on the ETH Zurich web site.

Tristán and Michaud

In a letter to the Times in 1932, CEK Mees mentioned long-distance infrared photographs of mountains, taken in Costa Rica 'in 1915 or 16' by Gustave Michaud and José Fidel Tristán, which were published in Scientific American. Researching to find this paper turned up a few interesting items by these two scientists.

The paper to which Mees referred turned out to have been in the December 26th 1914 edition of Scientific American and called Air Transparency for Infra-Red Rays. It did include views of mountains taken from San José in Costa Rica, demonstrating the haze-penetrating ability of near infrared. The plates used were spectrum plates by Wratten and Wainwright. These plates were produced sensitised to 800 nm but by using alizarin blue S the sensitivity was increased not only beyond 800 but also in terms of reducing exposure times to as short as two minutes at f8. One of those photographs is reproduced below.

Dragon Mountain from San José

In fact, the Scientific American paper was based on an earlier paper by Michaud published in the 7 September 1912 edition of the French scientific journal La Nature, including two of the San José photographs. This is remarkably early for published infrared photographs but we get a clue from the note at the start of the paper which says (in French) that Michaud was a student of Professor RW Wood. (You can access the paper, in French, on page 229 of this online digitisation of La Nature.)

It seems (assuming I am not confusing people with the same name) that Michaud was an American or Swiss (references differ) who had been in Costa Rica at the end of the 19th century working on surveying and mapping. If he was a student of Wood's then he presumably went (back?) to the USA to Johns Hopkins sometime between 1901 ... when Wood arrived there ... and 1912 ... when the La Nature paper was published, returning to Costa Rica and teaming up with Tristán. Tristán was considered an 'outstanding' Costa Rican naturalist, and published the first list of native insects (in 1897) with a species of flower fly named after him (ocyptamus tristani). I'll come back to the subject of insects in a later post but this duo collaborated during the decade on a number of applications of both infrared and ultraviolet photography.

Thus far these are the only people other than Wood and Mees of whom I have found evidence of work in infrared in the early years of the 20th century.

Emulating infrared Ektachrome

The false colour infrared Ektachrome (or Aerochrome) can be emulated with a digital camera. I had noticed, when researching my history of infrared photography, that early digital cameras did include infrared models.

The AP NC series, introduced by Kodak in conjunction with Associated Press in 1994, included an infrared monochrome model, the AP NC2000ir with a resolution of 1012 by 1268 pixels. The DCS 420 and 460 series, introduced in 1995, also included infrared but this time included colour models. The 1999 DSC 6XX series also included an infrared configuration. However, with the basic colour units selling for between ten and twenty thousand dollars, and the infrared versions being special orders on top of that, these were not exactly consumer cameras. The colour infrared cameras, such as the DCS 420, were simply colour digital cameras with the kind of Beyer tri-colour filtering that is still standard, but with the infrared-blocking filter removed.

The aim was to reproduce the false colour abilities of Kodak's EIR infrared Ektachrome and this could be achieved by putting a minus-blue filter in front of the lens. The blue channel then only contained infrared information and the red and green channels contained their colour plus some infrared 'leakage'. By calibrating the system and subtracting appropriate amounts of the blue channel from the other two a result similar to EIR could be achieved.

I'd tried this before, using a borrowed Canon but on a somewhat overcast day. Using my FujuFilm IS-Pro I've shot some more tests, such as the image above, of Eashing Bridge. That's how the raw image looked after each channel had been normalised (ie the darkest and lightest points set).

Using the Photoshop channel mixer, the red output channel is set to the blue input, green output is set to red input and blue output is set to green input. Remember the yellow filter will have removed any real blue from the image. Next some of the blue input channel (which is really the infrared) needs to be subtracted from the green and blue outputs. This is not scientific and is certainly uncalibrated but in this case subtracting 50% blue from the blue output and 65% of blue from the green output gave a suitable colour balance. I also played around with gamma and curves to improve the look of the image: as I said, it's not scientific.

This is the result:

Matson infrared photographs

An interesting and unexpected source of infrared photographs from the 1930s is the American Colony in Jerusalem, later the Matson Photo Service. According to the Library of Congress, where the collection [infrared photographs | whole collection] is now kept, the colony was “an independent, utopian, Christian sect formed by religious pilgrims who emigrated to Jerusalem from the United States and Sweden. The history of the Colony is intimately linked to the photography collection it spawned.” Eric and Edith Matson continued the photographic work in the middle-East and around east Africa after the colony broke up in 1934. They were innovative photographers working with infrared, colour, 3D and aerial photography although most of the collection is conventional.

This is one of the infrared plates in the collection, entitled Haifa, looking across the bay from Carmel showing harbour & Acre beyond. It's a 5 by 7 inch dry glass plate, which begs the question of where this was sourced. Given the climate in what is now Israel my guess is that the plate was sensitised locally.

More detailed information on the colony and the collection can be found on this LOC page. There are thousands of fascinating images in the whole collection and many of them can be seen online. You can find a few more infrared photos by searching using infra-red but this also hits a lot of false drops since the term appears in a general descriptive field (hover over the thumbnails of the first few photos to check titles for the word infra-red). I should also add that there are photos taken around Africa as well as in what is now Israel.

Top of the World with Albert W Stevens

This week's breathtaking freefall from 128 thousand feet by Felix Baumgartner has reminded me of another high-flying pioneer who also plays his part in the history of infrared photography.

Up to 1956 the record for a balloon ascent was held by Albert William Stevens and Orvil Arson Anderson of the Army Air Corps who reached 72,395 feet on November 11 1935 in their sealed gondola named Explorer II. They launched from South Dakota with millions listening on live radio. [Pathé newsreel coverage here.] Stevens and Anderson, together with William Kepner, had made a previous attempt, 1934 in Explorer I over Nebraska, but the balloon burst and the intrepid trio had to parachute to safety from the plunging gondola. There's a good piece about Stevens and the preparations for this ascent in the March 17 1934 Literary Digest. You'll note the photograph of him and a huge aerial camera, for Stevens was an accomplished aerial photographer.

Many of his photos were taken on infrared film, to combat the problems caused by haze when photographing from altitude. He took the first photograph to show the curvature of the earth and he photographed the shadow of the moon on the earth during the 1932 solar eclipse over the US. His images from Explorer II included the highest photograph ever made (a record that also stood until the 1950s) and covering the largest area ever taken with a single lens, showing a horizon around 330 miles away. (The specification was 1/25th second using a Fairchild F4 camera with a Kodak 304mm f5 lens on Eastman infrared Aero film through a red filter.) This wasn't the longest distance Stevens managed to photograph. His 1933 aerial photograph of Mount Shasta in California was taken from a plane flying at 23 thousand feet from a distance of 331.2 miles. The atmospheric haze rendered the mountain invisible, so the camera was oriented using a compass. The Mount Shasta photograph, courtesy of the Kodak Archive in Rochester, was included in the Infrared 100 exhibition.

Stevens's adventures were usually undertaken with the help of the National Geographic Society and stories of his exploits and many of his photographs can be found in editions of that journal from the first half of the 1930s. The Explorer II gondola is now in the US National Air and Space Museum.