Photography of shiny objects
Photography, the art of writing with light and the manipulation of light, requires that you take a focused look at the objects or scenes so as to depict in the most attractive and compelling manner. A dedicated photographer therefore continually analyses how to best depict the scene, varying the lighting and adjusting the arrangement, selecting an appropriate lens, exposure setting and depth of field, inspecting the results through the camera's viewfinder, taking due account of the light sensitivity of recording material.
By sidelighting the object from different distances with identical lights, it is unevenly lit. This is expressive lighting bringing about soft shadows which help our brain to perceive the three-dimensional structure of the object. One can also replace one light with a reflection screen.
|Side lighting. If the object is flat and shiny, only the edges will reflect the light and even lighting is called for. In other cases this lighting is suitable for enhancing the perception of depth, but then the lighting should not be equally strong on both sides (see illustration on the left.|
The lighting of an object is the determining factor for the brightness, the reproduction of colour in all its shades and for its representation as a 3-dimensional object. In general frontal light leads to flat images with little detail of surface and contour, which appears non-expressive; it is therefore called flat lighting. In the case of flat objects that is not a problem, unlike three-dimensional objects. In the case of flat, reflective objects, such as enamel panels and metals, frontal light is strongly reflected and the light source depicted, highly undesirable features. With front lighting, images of flat objects which have some relief, such as when made with the basse-taille or guilloche technique, badly miss the tonal variations that our brain uses to perceive depth.
Side light is expressive light.
Our brain perceives depth from perspective distortion and from tonal variations. Side light helps to bring about tonal variation. Lighting from one side (side light) with a small size light gives rise to hard shadows: dramatic, and useful for emphasizing a shape or accentuating three-dimensional aspects of flat objects such as an engraving or etched plate. It is not suitable for illuminating subtle details of jewelry of enamel work. A sense of depth without hard shadows is achieved by using a very wide light source, two light sources, or a light on one side and a reflection screen on the opposite side; the second light or the screen serve to lighten the shadows (fill light): the main light should be the strongest, because even lighting from two sides leads to a very unnatural image.
Occasionally it is necessary to use back-lighting, for example to best reproduce the colours and the pattern of a plique à jour object. As the metal then only shows up as a silhouet, it will be necessary to combine the back-light with a very soft front light or with frontal sidelighting.
Lighting can be “hard” or“soft”, depending on the size of the light source relative to the object. We speak of hard lighting when a source of light is small relative to the object and sufficiently far removed from it that its rays strike the subject from nearly the same angle. Examples or hard lighting: sunlight on a clear day, flashlight. Such light leads to a high contrast and hard-edged shadows shadows. Conversely soft lighting, where the rays are not in parallel and can strike the subject from many different angles, gives rise to soft, poorly defined shadows. Such diffuse lighting is emitted e.g. by the sun on a cloudy day, light from a light bulb with a very wide reflector placed close to the subject, or from indirect lighting via a reflective screen or through a diffuser.
|The object is illuminated indirectly via een white, translucent screen. This causes diffuse lighting, preventing reflections from the light source to show up as specular lights. Also the softer light does not give rise to hard-edged shadows, and the lighting of the object is more even and natural.|
In the case of flat enameled objects, where one is concerned predominantly with a good reproduction of the colours, two sidelights which light the object evenly often suffise. The surface is usually not perfectly flat, and may give rise to some specular reflections. That is not a problem, as a few small reflections accentuate the structure of the object and accentuate its three-dimensional structure. Carefully inspect the scene through your viewfinder and move the light sources until you have found the lighting that you like best. If you use flashlights or two light bulbs, then do not place them close to the object as this may give rise to uneven lighting: the brightness of light decreases in proportion to the square of the distance from the source.
Direct lighting is associated with high contrasts. There are circumstances such lighting is not called for. For example when you use transparent enamels, where the hard light may give rise to hard-edged shadows. In addition the light is dispersed by the deeper enamel structures and bounces from the back of the panel, diminishing overall contrast and softening or obliterating subtle details. This is a case where you want to use soft lighting. Study the four images below to see how different lighting affects the image; the object is a copper panel enameled with translucent enamel. As a rule of thumb, use soft light if you reproduce such objects. If you allow a flat object to directly reflect diffuse light, this brings surface detail to the fore at the expense of detail of the underlying pattern, as shown below.
|Sidelighting with soft light through a transparent reflection screen.||Direct sidelighting. Note that most of the green enamel is no longer reproduced; the image is brighter and has poorer contrast.|
|Front lighting on the left through a transparent reflection screen positioned so that the enamel reflects some light; direct sidelight on the right.||Front lighting through a transparent reflection screen on both the left and right, positioned so that the enamel reflects some light.|
|Above is a tent made of white, translucent paper or frosted plastic. Below is a tent using e.g. white paper on a roll, which provides a seamless 'box', and lighting from above either through a light bulb with a wide reflector, or via a transparent screen; the open sides can be closed with white material.|
Shiny objects such as silver, which reflect their surroundings, require soft, diffuse light. To that end one can take pictures outside with the sun behind a thin layer of clouds and some reflection screens (e.g. a sheet of white wallpaper or a polystyrene sheet) to provide desirable reflections from the surroundings. In the case of round or cylindrical shiny objects, which reflect so much of the environment, a light tent is a useful tool for creating a light environment. You can make one yourself. If you model it like a lampshade out of translucent paper or frosted plastic, the opening at the top can be used to take the picture.
Obviously the lens and part of the equipment might be reflected in the object, but either the reflection is very small and easily overlooked, or you must find a way to camouflage it. At the base the tent should be wide enough to place the object comfortably and to fill the focal plane; also the height should be suitable for the lens you are going to use.
The light tent can be illuminated from the outside by a number of light sources at distances you select, allowing if you wish some less bright parts to be reflected. Maybe you are after some darker reflections. In that case you can locally apply poorly translucent or opaque material to the outside of the tent. You might also consider a tent made of opaque white material; it should then be lit from the inside, and in the case of round and very shiny shapes the light source will be reflected. The tent can take any form, such as a pyramid or a box. I often shape transparent diffusion screens and use outside lighting. Thus you can shape 2 circular Lastolite screens around the object, leaving an opening for the camera lens. Sheets of Styropor are cheap, white, and they form excellent reflection screens that can be made to any shape by cutting and glueing.
|The tent is illuminated from below, so as to obtain shadowless lighting. The object is placed on an opaque base, preventing direct lighting of the camera lens.|
One can also obtain practically shadowless images. A shadowless image provides no clue whatsoever about the third dimension of objects and is therefore usually quite dull. However, occasionally the shadow may distract from what you want to demonstrate. You can achieve shadowless lighting by using a white tent-like structure as depicted on the right, and lighting it from below. Put the tent on a sheet of glass and hide the light bulb at the centre using an opaque material (a gobo), leaving a ring through which the interior of the tent is lit. Put the object on any base you like, on top of the gobo.
For most purposes you can easily build your own contraption, using variations on the above theme and applying the principles discussed.
Light tents are quite suitable for depicting silver and other shiny metals. However, as the lighting is very soft they are not suitable for all jobs. For example, the brightness, structure and beauty of precious stones is best emphasised by specular reflections and tonal variations. Similary the light may be too soft for objects if you want the picture to show the surface structure. In such cases, combine soft light with a small light source aimed at the precious stone, and surround the object with white screens to obtain appropriate reflections.