ISO (once referred to as ASA): every film has two important qualities -- speed and sensitivity to light. This is indicated on the film being used by a ISO (International Standards Organization) number -- 100, 200, 400, etc. The higher the ISO number the faster the film and the greater is its sensitivity to light. Film quality today is excellent; however, the use of a higher ISO film, 400 or above, may mean a lower quality picture due to the weaker colour balance quality of the film and its tendency to produce, in enlargement, greater graininess. It is generally recommended that a medium speed film -- ISO 100 -- be used in photographing art work.

Colour Balance: most colour film is colour balanced for daylight conditions (5400ø Kelvin) and for flash photography. For artificial light conditions, an indoor film -- often referred to as Tungsten film --can be used. However, unless photographic tungsten lights are used, colour balanced for 3200ø Kelvin, the colour on tungsten film will be off. For example, the average incandescent light is 900ø Kelvin, and will render a reddish cast over your pictures.

In using daylight film in an artificial light environment, a colour correction filter must be attached to the lens (Expensive! and never quite exact without a lot of experimentation with the many filters). As an alternative, you can use blue photoflood light bulbs (Cheap!), which are supposedly balanced for daylight film. But they generally are not and, to complicate matters, they quickly lose their "blueness" (maximum life is 4 hours) and a reddish cast results. This can be corrected somewhat by attaching an 82A filter (light blue) to your lens. I would suggest that this filter, which has such a small filter factor that it does not have to be taken into account when getting the correct exposure with which to take a picture, be used regardless of the quality or newness of the bulbs, for experience has suggested that blue photoflood bulbs rarely achieve the colour balance required, especially for accurate slide documentation. Also, once the bulbs have been used extensively, discard them. The 82A filter will also fade after extensive use and must be replaced. If you shoot your work and find a reddish cast occurring or, for example, that silver looks yellow, the bulbs or the filter used are the usual problems. With modern print reproduction, however, colour balance can be adjusted at time of printing to the natural hue desired, and thus bulb life and filter correction are not as critical. Unfortunately, this does not apply to slide reproduction, so greater care must be made to get everything right the first time.

Depth of Field: (sometimes referred to as Depth of Focus) refers to the three points of perspective on the picture plane: foreground, middleground, and background. In photographing two-dimensional work, the question of Depth of Field is not terribly important. If three-dimensional work is being photographed, Depth of Field is critical. Depth of Field is determined on the lens by what are known as f-stops, which determine the aperture of the lens being used to make a picture.

F-Stop or Aperture: The smaller the aperture, the greater the Depth of Field; the greater the aperture, the smaller the Depth of Field. This is the most important rule in photographing your art work. It means that f2.8 (large aperture) on your lens will give you very little depth of field. That is, only the area of focus, possibly the middleground, will be sharp. On the other hand, f16 (small aperture) on you lens will give you a lot of depth of field. Much, if not all, of the foreground and background will be in focus.

Depth of Field must be predetermined before making a photograph to get the results you envisage. It is a complicated subject about which whole photographic books have been written, and it might be well to read extensively on the subject of Depth of Field if you are photographing 3-D work or items small enough as to require close-up or macro photographic techniques. A general rule, however, is to focus one-third into the picture, and give yourself at least an f11 aperture. Study your results and that will give you a lot of information on what aperture to use in what circumstances in the future.

NOTE: some SLR cameras come equipped with a Depth of Field preview button. When purchasing a SLR camera, try to get one with this feature. It saves a lot of headaches.

Exposure: refers to the amount of light that comes through the len's aperture and through the open shutter. It is determined by a reciprocity of f-stop (lens aperture) used and shutter speed used. Since Depth of Field is very important in photographing your art work, the shutter speed used to make a picture must be correct for the aperture used to achieve the needed Depth of Field. This shutter speed can be determined by using the camera's exposure meter.

Set the required f-stop for the desired Depth of Field, then select, using the exposure meter, the shutter speed the meter suggests correct for the lighting conditions the meter is reading. It helps if you read your camera manual to know how your meter works before you undertake this adventure. Otherwise, you will find wrong exposures occur as matter of course.

However -- the exposure meter reads reflective light. That is, it reads the amount of light being reflected off the object being photographed. If an object is too light or too dark in reflective quality, then the meter will not read it correctly. This is because the meter is set up during manufacture to assume that the object has a reflective character that is average to 18% gray, or middle gray: it is characterized in tone by equal amounts of white (highly reflective), gray and black (highly absorbent) colours. To put it bluntly, the manufacturers were not thinking of photographing art work when they set up the metering system. The camera meter works miracles when photographing landscape. It does not work well when photographing art work. The reflective quality of most art work is not average or, if you like, scenic.

Gray Card: A more accurate exposure reading for photographing a lot of art work can be obtained by taking a meter reading off an 18% gray card (Cheap!) or by using an incident light hand-held meter (Expensive!). Gray cards can be purchased at camera shops, or can be made yourself by mixing black with white paint until a middle gray tone (zone V, in photographic terms) is achieved. Find a piece of solid white card and paint it this middle gray tone. Works every time in helping to achieve correct exposure for photographing your art work!

However, even then adjustments must be made when using a Gray Card. Aim the meter at the card about 6 inches away from its surface, making sure not to cast a shadow on the card, to take a reading. Further adjustments to the meter reading must be made if the object being photographed is three-dimensional. I would suggest the following procedures, particularly for 3-D work.

If the main source of light is from the front or side of the object being photographed, hold the card so that it is angled to face halfway between the camera and light then take a meter reading. If subject brightness (reflective quality) is normal, increase the exposure by « stop over what the meter suggests. Thus, if you are using F8 as your f-stop, use F7 (or the stop between F5.6 and F8) for correct exposure. Of course, if you require at least an F8 for correct Depth of Field, set the f-stop at 11, and deduct « stop to F10, the stop between F8 and F11. Naturally for correct exposure, a reciprocity adjustment in the shutter speed must be made for F11 before this « stop correction is made.

If subject brightness is slightly darker than normal increase exposure by 1 full stop, using the shutter speed only. That is, if your shutter speed for F8 is 60, increase exposure by adjusting it to 30. If the subject brightness is very dark, increase exposure by 1« stops, by using a combination of the above methods.

The reverse is true for lightness. If subject brightness is slightly lighter than normal, use the reading indicated by metering the Gray Card. If very light, decrease exposure by « stop, that is moving the F8 to F10, the stop between F8 and F11.

I know this sounds very confusing, however, take careful of notes of your procedures, and when your pictures/slides are returned carefully go over them and decide what works best. Note this success, and thereafter you will find you can duplicate results without difficulty and waste a lot less time and film.

If the main source of light comes from behind the object, as it often most effectively is in 3-D work to achieve a statement about the outline or shape of the object, hold the card with gray side facing the camera, shadow the meter so the light does not fall on it, and measure what is in effect the shadow brightness. You will be using a secondary or reflective light source to enhance the shadow brightness, so make sure that this is in place when metering the Gray Card. More on that in lighting procedures which follow.

You will have to make further adjustments, and to determine these, the best procedure is to take a picture at the exposure suggested, then bracket exposure in « stop increments over and under the suggested exposure to a maximum of 1« stops each side, for a total of five shots. Check the results when the pictures are returned, and find the one that works best. Make note of it and what exposure worked so you can duplicate it the next time you have a similar lighting set-up.

LAYOUT & BACKGROUND

A simple, clean presentation that highlights the form, structure, texture and colour of your work will produce the best photographs of your art work. Taking time in setting up the environment in which your work is photographed will pay off in good pictures that present your work in the best light.

Two-Dimensional Work: should be photographed against a neutral background or backdrop -- black, grey, brown or white wall, for example (Cheap!) -- or against photographic no-seam paper (Expensive!).

Works of art should be photographed unframed and without a matt, if possible, as both will cast shadows on the work. Glass over a watercolour or print, for example, will reflect objects in front of it (including the cameraperson), and it has a tendency to cast a coloured haze that will distort the true colours of the work. If you must shoot a work already under glass, use a polarizing filter to reduce glare and reflection. You may also use a large black card, in the center which a hole the diameter of your lens is cut. Place this over the camera lens, so that all is hidden from reflective view except the lens itself. What will be reflected by the glass is the black card.

NOTE: use of a polarizing filter reduces the amount of light reaching the film and, therefore, compensation of this filter factor must be made in determining the final exposure reading to be used. In other words, if using a gray card, take the meter reading with the polarizing filter attached to the lens.

You will find, of course, that most 2-D work is not the same rectangular shape as the 35 mm film frame, and that some background will show either at the top or on the sides of the picture being photographed. Thus the use of a neutral background assures that this extraneous background will not detract from the work itself. Be sure to balance the background that shows evenly on the sides (or top and bottom) in composing the picture.

Three-Dimensional Work: should be photographed against a background that is neutral or produces a pleasing contrast with the dominate colour of your work. The viewer must be able to see clearly the contours or edges of your work.

Stay away, if possible, from a natural setting -- unless it is an essential part of your work, as it might be in installations, earthwork, some sculpture and crafts in situ, etc. Natural settings tend to distract the viewer away from your work, as do such wall materials as brick, clapboards, etc.

Take photographs of several viewpoints of your work so that the viewer can imagine the work "in the round".

LIGHTING YOUR WORK

If using natural daylight in photographing your work, a diffused light (often referred to as "northern light") is often preferred over direct light which may cast heavy, unwanted shadows or unseemly glare. For example, in three-dimensional work, a shadow can be seen through the camera lens as part of your work. In contrast, your eye unlike the camera lens tends to differentiate between the work and the shadow. Be aware of this difference in view when planning the lighting to be used after setting up your work for photography.

If using artificial light, black out window light as much as possible, and turn off room lights. This will not let a mixing of variety of degrees Kelvin possible in different types of light to occur and thus this will avoid an odd colour cast being observed in the final photographic version of your work.

Two-Dimensional Work: requires a single diffused light falling evenly across the picture's plan, if using natural light; or, if using artificial light, two lights, each set 45ø to the center of the work. Having placed your work against a neutral background, run chalk-lines or masking tape along the ground or floor in two directions (one to the left, one to the right), both at 45ø from the center of the work, to points equal distances from the work. Mark these two spots, and place on each an artificial light (blue photoflood clamped on a stand, for example) pointed along the lines towards the center of the work.

Check whether the light falls evenly over the whole object by touching the end of a pencil to the object and measuring the shadow on each side of the pencil. If the shadows are of equal shape and intensity your lighting is perfect.

For exposure, use the Gray Card set in the middle of the work and take a meter reading. Make adjustments for the reflective quality of the work. Thus if a painting is dark in tone, be sure to add exposure by adjusting the aperture or shutter according to degree of darkness, « to 1 full stop. The opposite procedure is true for objects of a lighter reflective quality.

Three-Dimensional Work: requires one main or key light and a secondary or fill light for effective photography. The fill light should have about one-third the intensity of the key light, and it may simply be a reflector made of cardboard or styrofoam covered in foil, crumpled first for diffusion and to avoid glare.

After the art work is placed against the correct background required to enhance the work, set up the key light at an angle that will give you the best lighting and shadows for the presentation of your object. This is usually from the high left side, even towards the back, of the object, so that the contour of the object is well presented.

NOTE: if the diffused sun is your key light, either out-of-doors or coming through a window if photographing indoors, set up the art work with the sun to its high left, moving the object until the lighting is effective. If using "window light", make sure room lights are turned off.

Then set up the fill light opposite the key light at a distance that best fills in the shadows.

Once the lighting is set up, take a reading at the object using your gray card. Lock in the camera meter reading. Set the camera on a tripod and frame the picture correctly. You are now ready to take a picture. Make sure to make any exposure adjustments necessary in terms of the reflective nature of the object, as outlined in "Exposure" above, before taking the picture.

BUYING INSURANCE

Film is cheap. Professional photographers in photographing objects or scenes use exposure bracketing to insure that exposure of the final picture of the object is correct.

First, take a meter reading, using your gray card, and lock it in. Make any adjustments according to the reflective quality of the art object. Take the first picture with this reading. Take a second picture by changing the shutter speed on the shutter dial on the camera body to one number below the one used in the first shot. Take a third picture by moving the shutter speed to one number above the one used in the first shot. You will have taken three pictures, but one, probably the first taken, will be the best for your purposes.

Because you are taking pictures to document your work, you will use the best picture(s) taken of your work for many purposes. Have quality copies made for your files. Keep the slides and prints of your work in archival sleeves on file, perhaps in a binder, and in a dry, secure place.

The above procedures are complicated, but practice, including careful note-taking, makes perfect. If you learn to photograph your own work correctly, you will save yourself a lot of expense. Professional photography is expensive, for you are paying for a very specialized skill. As an artist you want to maximize profits, so learn to photograph your own work.