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Friday, May 4, 2012

Photographing in Invisible Light: Infra Red Light

Photographing in Invisible Light: Infra Red Light



The ‘normal’ light conditions are available in general situations and it been estimated that an overwhelming majority of 98% photographs are taken in visible light.

However, as elementary physics has taught us the range of light goes much beyond the normal light. Normal light has wavelength range of 400 nm to 780 nm. As we move towards the shorter wavelength bandwidth we enter the ultra violet range and as we move towards longer wavelength we encounter Infra Red (IR) light bandwidth with wavelength approx. 300 micrometers.

Most of the modern day digital cameras are sensitive to IR light are capable of capturing images in IR bandwidth.

But, why bother with capturing photographs in the IR? The answer is simple: the resulting images are surreal and almost magical in appeal. The normal photograph with green leaves and grass of the foliage suddenly transforms into silky white scene with type shades for other objects.

Once, simple way to find if your camera can shoot / capture IR images, just point your camera towards your TV remote and if you can see a white spot emitting from the remote, then your camera can shoot / capture IR. Else, your camera is not sensitive to IR light and will not capture any such images.

IR Photography has been used by the experts in the field of military and widely for astro-photography for a long time. Digital photography makes it real fun and easy to capture photographs in IR and that alone can be compelling reason to try IR photography as a hobby and a new avenue to experiment.

The most common IR bandwidth that will of interest to us is wavelengths between 700 to 1000 nm. This Near Infra Red (NIR) range is commonly captured by modern day cameras; both point and shoot as well as D-SLR.

In the years gone by, there was IR film used by yesteryears photographer to capture IR photographs. The IR camera rolls being more sensitive to light; require special handling in the dark-room, making the process cumbersome and daunting for even the most experienced ones.

IR Enabled Camera:

In some of the modern day digital cameras, there is an additional special filter over the image capturing sensor, that blocks most of IR light and allows only visible light to pass through. This filter is called IIRC – Internal Infra-Red Cut Off filter, which can removed by specialized training personnel in the select camera repair outlets. The resulting digital camera becomes a dedicated IR camera and cannot be used for conventional photography, thereafter. But, for the IR photography enthusiasts, this becomes a valuable possession and these cameras are much more sensitive to capturing wider range of IR spectrum and producing images of highest quality.

Post-Product IR Option:

 Since, not everyone wants a dedicated IR camera, the most popular option becomes to convert a ‘normal’ photograph to IR simulated one.

Here are the steps in one of the most popular editing software – Adobe Photo Shop:
:

1.       Using any D-SLR, capture a photograph in the B/W mode. Most, of the D-SLR cameras have this option. Converting a color image B/W in editing software, with result in loss of IR range covered.
2.       Use TIFF format instead of JPEG, to get best results. You can easily convert a JPEG to TIFF.
3.       Open the image file in Adobe Photo-Shop
4.       Open the Levels dialog window (Image > Adjustments > Levels) and adjust as needed by dragging black triangle just under the left edge of the graph and the white triangle just under the right edge of the graph.
5.       Review the changes in image, so that you get the look you want.
6.       The next step is to convert the file from RGB to Grayscale (Image > Mode > Grayscale). Click OK to discard the color information and create a file that looks like a black-and-white IR photo.

This is one of the simplest way to convert a B/W photograph to IR one. For higher quality results it is best to shoot in RAW mode of the digital camera and convert it to 16-bit TIFF.


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