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UltravioletPhotography

Alpine landscape. Combined UV and IR


nfoto

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As a precursor to using UV for landscape photography, it can be useful to look into the various spectral bands available to invisible spectrum usage. One can combine bands to make false-colour, multispectral composites. There are virtually endless combinations to explore.

 

Here are a few early experiments on an alpine landscape at Jotunheimen Norway. Taken with a broad spectrum modified D1 and the Nikkor 28 mm f/3.5 lens. This lens is usually regarded as excellent for IR photography, but its UV propertiers are less familiar. While it certainly does not transmit deep into UV, it can depict the usual test objects such as UV patterns of a dandelion in a satisfactory manner.

 

For this hastily improvised trial I used a combination of UV and two IR bands. I had no suitable bandpass filter for visible at hand on that trip. All captures were conducted at f/16. The mountain air was crystal clear and cool to give little turbulence and excellent visibility even of the remote peaks (up to 15 km away). First autumn colours had started to appear (this was mid August, 2004).

 

ALPINE_T0408136757_UV.jpg

UV light: Hoya U-360 stacked with B+W BG-38.

The ground vegetation is rendered fairly dark and the sky is bright. Water surfaces reflect sky and thus are rendered rather bright as well. There probably is some IR contamination present in this capture due to the non-optimal filtration, but the expected UV appearance is present.

 

ALPINE_T0408136743_RT830.jpg

IR band 1: Hoya RT-830 filter, with a peak around 830 nm and having fairly strong attenuation to either side of the peak. This represents the middle section of the near photoactinic IR. As expected, vegetation is bright and sky and water show up quite dark.

 

ALPINE_T0408136747_IR1000.jpg

IR band 2: Hoya RG1000 filter, starts to transmit around 950 nm and is fully transmitting above 1000 nm. The IR character of the landscape is very strong. Sky and water surfaces are jet black, while vegetation is medium grey to bright depending on vegetation type and ground moisture.

 

When these three are combined into a false-colour composite, or multispectral image, the following picture results:

 

ALPINE_T04081397513_MS(UV,IR).jpg

Image reference: :ALPINE_T04081397513_MS(UV,IR).jpg

Here, UV is coded B(blue), IR 1 is G (green) and IR 2 is R (red).

 

In the composite, the haziness brought by the UV band tends to blur the distant mountain peaks.

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