Transcript of the video "Lighting Techniques for Photographing Heritage Objects"
Video length: 00:04:05
During the conservation or the analysis of an object, photos serve to keep a record of its condition and to help the conservator propose the best treatment. Here we have an artwork with embroidery, silk, metallic beads and drawings mounted on a wooden frame.
Normal light is the most common type of lighting used in heritage institutions. It is often used for general photography, preservation imaging and beauty shots for catalogues. With lights positioned at a 45-degree angle on both sides, it evenly illuminates the surface and reveals the true colours and tones of an object. This lighting also exposes surface dirt and discolouration, reduces glare and conceals damage along with the texture of the material.
Specular light reveals the sheen and the matte surfaces of an object, as well as some of the texture and damage. The light is placed at a 90-degree angle to the object, exposing the cockling of the canvas, the sheen of the embroidery and the metallic beads. Here we can see that the canvas has shifted with time, causing rippling in the fabric.
Raking light accentuates the texture and surface damage. One light is placed at a low (5 to 10) degree angle relative to the object's surface. In this example, we see tears and additional cockling in the canvas that are not revealed in normal or specular lighting.
Transmitted light illuminates the object from behind and is useful in illustrating an object's thickness and any puncture holes or tears. In this example, we can see the thin silk in the sky and the thicker embroidery below. We are able to differentiate drawings and pigments from the embroidery. Transmitted light indicates where the embroidery has distorted and is offset from the stretcher frame.
With its signature violet tint, ultraviolet fluorescence is the emission of light caused when an object is exposed to UV radiation. Two UV sources are placed on both sides of the object, as is done with normal lighting. It enables the conservator to differentiate between original and modern materials and to identify areas that have been retouched. Here we can tell that a substance has been applied over the church and clouds because the substance fluoresces orange under UV radiation.
Near-infrared photography can reveal underdrawings and provide a clearer view of faded or obscured writings. To record near-infrared radiation, we use a high-intensity studio flash and a camera that has been modified to receive only infrared radiation. Here, the church, the cross, the hands, the crucifixion of Christ and the skull are revealed to be graphite drawings.
Radiography is a non-destructive examination. It is useful to see through the different levels of density of an object and in some cases, to uncover previous restorations and compositions. When X-ray radiation is emitted, it passes through matter and is recorded on an imaging plate. White indicates denser material, like the metallic beadwork, and black indicates thinner and lighter material, like the silk and embroidery.
CCI is equipped with an industrial radiography lab and can provide this highly specialized examination for our clients.
These are but a few of the lighting techniques which can be applied by the heritage community. For more information, consult the CCI publication Lighting Methods for Photographing Museum Objects or attend the two-day in-person workshop "Digital Photodocumentation of Museum Objects," led by CCI's Scientific Documentation Technologists.
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This video presents seven lighting techniques used to photograph heritage objects during their conservation or analysis. This video was created by the Canadian Conservation Institute.