|Inexpensive Lighting &
Choosing the Correct Film for Your Lights
by Mark D. Thellmann
The least expensive lighting instruments would be a couple of hardware store clip lights with 10" aluminum reflector bowls and two 3200 degree Kelvin photoflood bulbs. These lights could be clipped to makeshift light stands comprised of PVC or metal tubing cemented or plastered in coffee cans. Some very successful professional photographers started out this way.
Note that all tungsten light is incandescent light (what Thomas Edison invented), but not all incandescent light is tungsten light because of the 3200 degree Kelvin rating. A standard 60 watt light bulb is not rated at 3200 degrees Kelvin. You must purchase specially manufactured photoflood bulbs like the EAL or ECT. These bulbs, rated at 500 watts, are inexpensive, but short lived. Some last only 3-4 hours, but their 3200 degree temperature is constant and made for tungsten slide film.
The next level of expenditure would be to invest in some actual light stands and lights with bowl-type reflectors and barn doors attached. These light heads will have fittings which allow them to mount on the light stands. They also require the aforementioned photoflood bulbs. The Smith Victor Co. manufacturers a basic, but inexpensive and very practical light kit carried by larger photographic supply stores.
Moving up in price again, we would purchase heavier light stands and quartz tungsten light heads with barn doors. Quartz tungsten bulbs, also rated at 3200 degrees Kelvin, are more expensive than photoflood bulbs, but last roughly 100 hours. Unlike tungsten photoflood bulbs, quartz tungsten bulbs do not screw in. Photoflood bulbs cannot be used in these lamp housings. Please note that this type of lighting is called "hot light" for a reason. Wear a pair of gloves so you don't get burned adjusting barn doors or when attaching gels or diffusion materials to them.
Another common light source is cool white fluorescent lighting. It is usually found in schools, offices, cafeterias, grocery stores, etc. Never shoot anything under this light. On daylight film, this light source photographs green and on tungsten film, it photographs an aqua color. If Picasso's "blue period" work had been photographed under cool white fluorescent lighting, history would have referred to it as his "green period." There is no film on the market today that will reproduce colors correctly under cool white fluorescent lighting. You must rely on filtration.
If for some reason you have to photograph an art installation under this lighting and cannot utilize your own lights, use daylight film and put a Kodak Wratten 30 or 40 magenta filter over the lens. This filter should absorb the greenish cast. Also remember never to mix your light sources. Fluorescent from the ceiling and daylight from the windows will change things considerably, as will tungsten mixed with daylight.
Matching the right film with the right light and keeping that light source constant in color temperature will result in slides that will reproduce the colors in your artwork accurately.
Matching Film with Lighting There are basically three types of 35mm film: slide film, color negative film, and black and white negative film. Since slides are usually required for juried show submissions and many people believe that slides, being "first generation", are the best choice for printed reproduction on such items as post cards, business cards, note cards, catalogue sheets, etc., we will discuss only slide films for the reproduction of artwork.
The word "slide" refers to the 35mm format. Larger formats such as 2&1/4, 4x5, and 8x10 refer to this film as "transparency" film. Your exposures must be accurate when using this film. It possesses a most limited three-stop range; however, when great lighting and perfect exposure come together, the beauty of this film is unsurpassed.
There are two kinds of slide film: daylight balanced slide film, which is rated around 5600 degrees on the Kelvin scale, and tungsten balanced slide film, which measures 3200 degrees Kelvin. Because of this difference in temperature rating, daylight slide film shot under tungsten lighting will exhibit a yellow-orange cast and tungsten film shot under daylight will exhibit a blue cast. Filters can correct for this, but it makes much more sense to shoot the right film under the right light.
If you want to copy your artwork using daylight film, your light source must be daylight: light provided by the sun or the equivalent such as flash (also known as "strobe.")
Direct sunlight is very harsh and contrasty often superceding our limited three-stop range, which means we will lose detail in the shadow areas and our highlights will burn up. The soft light found in shade or an overcast day is better, but often exhibits a blue cast inherited from the sky. An 81 series filter (A,B,C) will help subtract this blue tint, but the point is that natural daylight is a highly unreliable light source when photographing artwork.
If you decide to use strobe or flash with daylight balanced slide film, it will be necessary to invest in a light meter which also measures this type of light. A light meter and good strobe equipment is expensive. A "daylight correct," blue-colored, photoflood bulb is manufactured, but it only lasts three or four hours. Its purpose is rather contradicted since daylight film is not really made for long exposures because it quickly exhibits reciprocity (the loss of sensitivity due to abnormally long or short exposures) and this bulb is not bright enough to afford the fast exposures flash or strobe offer.
This is why we will only discuss tungsten light and its partner, tungsten film. Tungsten slide film is manufactured by all of the major film companies. Kodak makes two tungsten Ektachrome slide films, one rated at ISO 64 and the other rated at ISO 160. Fujichrome makes a tungsten slide film also rated at ISO 64. The Scotch/3M company makes a tungsten slide film rated at ISO 640! It's fast, but incredibly grainy and should not be used in the photography of art and craftwork.
Obtaining the Proper Photographic Exposure Kodak makes what is called a "gray card," as an aid to perfect exposures, but I have always found this term misleading. This card just happens to have been printed a neutral gray color, but more importantly it is a surface that reflects exactly 18% of the light that strikes it. Many other colors can do this if they are of like density, not just the color gray.
This 18% is a "magic" percentage, because it is what all light metering devices are calibrated to in order to obtain the perfect exposure for the film you are shooting (providing you remembered to set the ISO number correctly, if your camera requires you to do this manually.)
Most of the time, what you are photographing in nature is reflecting light at this 18% value, but when photographing artwork, unless we are aware of this 18% value, we may get the wrong exposure.
For instance, if you are photographing a painting with dark tones, the meter will measure the light reflecting at 18% (that's all it knows how to do), but the painting is reflecting light at maybe only 9% (its tones are dark and dark means more light is being absorbed than reflected), so the slide is going to come out overexposed one stop (9 is half of 18) and that means the slide will be twice as bright as it should be, leading to loss of detail, tonality, etc. and you will be heard throughout the processing lab exclaiming, "I've lost my detail... my tonality!"
Exactly the opposite happens with a painting that incorporates a lot of light, airy, soft pastels. This time you will say, "I've lost my light, airy pastels. This is too dark. It's all blocked up!"
So, how do we get the correct exposure? There are three ways that I know of...
1) Take a TTL (through the lens) meter reading with your camera. If what you are photographing is reflecting light at 18%, your exposure should be right on (providing your camera is working correctly and the lab doesn't process your film in exhausted chemistry.) If you suspect otherwise, you can bracket your exposures by 1/2 stops: include a half stop overexposure and a half stop underexposure or...
2) Place the gray card in front of your subject and take a meter reading using it by first focusing on the artwork and then carefully removing the camera from the tripod and moving it in so that the gray card completely fills the viewfinder (do not refocus or you will affect bellows factor). Then take your meter reading making sure neither you, nor the camera, is blocking any of the light or you will be measuring shadow. This should be the proper exposure because you have provided the meter with a source having an 18% reflectance value, which is what the meter is clamoring to see.
3) Use a hand held incident light meter and measure your lights directly. Incident meters are not influenced by how much light is being reflected or absorbed by the subject. This is the way they do it in Hollywood.
4) Take a reflected meter reading and an incident meter reading and average the two together. Use this exposure.
If you have taken copious notes, you will be able to determine which method works best for you and finally exclaim, "I am a great art photographer! Just look at this!"