Let's say you're photographing a painting hanging on a wall. If the center of the painting is five feet off the ground, you'd start by placing your camera on a tripod so that the lens is centered on the painting—five feet off the ground. If the camera position is tilted up or down, the lens axis won't be perpendicular to the surface of the artwork and you're going to get distortion.
Set that camera on a tripod, and use a cable release and mirror lockup to minimize shake. I use a Manfrotto 410 Junior geared head, which makes tiny adjustments really easy. These are critical for keeping straight lines straight. You can use a bubble level mounted to the camera's hot shoe, or on some cameras (such as the Canon EOS 5D Mark III) there's a built-in digital level that can be displayed on the LCD. More important than the camera being level, though, is that the camera is square with the artwork. For that, take your time and pretend you're working with a single sheet of film and a large format camera. You'll move more deliberately and be more precise.
One way to ensure that your camera is positioned perpendicular to a wall on which artwork is hung (assuming, of course, that the wall and artwork are fairly flat and hanging close to parallel) is to use the same shortcut carpenters do. The 3-4-5 rule is a quick and easy way to make sure that a square is truly square.
The 3-4-5 rule says that if a triangle measures 3 feet on one side and 4 feet on the next, then the third side must measure 5 feet for the triangle to produce a 90-degree right angle. In practice, I mark the base of the wall below the center of my artwork and measure along the baseboard three feet, then (from the center position again) I measure out toward my camera four feet. That sets me up for a straight line connecting the two marks to measure 5 feet long. When it does, the camera angle is perfectly perpendicular to the wall.
There is a simpler way to copy flat work without hanging it on a wall, and that's to use a copy stand. If you're dealing with an image not much larger than 11x14, there's no reason not to use a copy stand if it's available. The copy stand turns the wall setup on its ear, placing the artwork on a table and suspending the camera perpendicularly above it. It's a great way to copy small items quickly, accurately and efficiently. When I shoot on a copy stand, I tether my camera to a laptop to see what's going on through the virtual viewfinder rather than trying to get my eye up and over the camera in that impractical position.
While you're in the Info Palette, you can check something else equally important without moving the eyedropper at all. Remember how we examined Red, Green and Blue values as a method for determining brightness? The difference in those values is a great way to measure neutrality as well. If a tone is truly neutral, each of the values will be about the same. A reading of 245/245/245 indicates a bright white without any color shift—i.e. correct white balance and neutral whites in the highlight areas. A reading of 10/10/10 represents a dark black pixel without any color shift in the shadows, and a reading of 125/125/125 represents a nicely neutral middle gray.
When it comes to lighting, whether the subject is hung on a wall or laid on a copy stand, the traditional approach is to use two lights placed on each side of the camera and moved beyond 45 degrees from the lens axis. This is to keep light from creating visible reflections on the surface of the artwork. Move the lights too far and you may start to see shadows from texture or a frame. It's best to move the lights far enough so that reflections disappear, but no farther.
If you're dealing with a particularly tricky subject in terms of reflections, a polarizer on the lens—and even polarized gels on the lights—can eliminate stubborn reflections from many surfaces. I work without them unless necessary, as the increased contrast from a polarizer may not be ideal.
Whether you're using hot lights or strobes, it's best to create the most even lighting possible. Aim each light past the far edge of the artwork in order to compensate for falloff and minimize hot spots. This is known as feathering the light, which will look more even across the frame. You can check this evenness with a handheld incident light meter.
It's also helpful to keep lights fairly far from the artwork. For a poster-sized piece of art hanging on the wall, positioning each light at least 8 or 10 feet from the subject will help minimize falloff. You can imagine how a light placed close to the subject will be very bright at the edge of the painting closest to the light source, and considerably darker on the opposite side of the frame. The closer the light, the more pronounced the falloff will be. To make even illumination, move the lights back at least three times the longest dimension of the artwork if possible. A three-foot-wide painting would want lights at least nine feet away to minimize falloff. If you're only using a single light source, even farther away would be helpful.
One important step when lighting copy work is to prevent lens flare from ruining the shot. When I work on a copy stand I'm usually able to get the lights above (and therefore behind) the lens to minimize flare. But when I'm shooting artwork on the wall, a couple of flags on C-stands, along with a lens shade, help prevent flare from light falling toward the lens.
If you haven't selected a lens already, this is the time. A macro is immensely helpful for copy stand work, and focal lengths between 50 and 100mm are my most often used lenses. I prefer the 100 whenever possible. Positioned necessarily farther from a subject, it helps to prevent the optical distortions you may see when working closer with a wider lens.
As for camera settings, when it comes to copying flat art, depth of field isn't usually a concern—though sharpness really is. Choose one of the sharpest apertures on your lens. If you haven't tested your lenses, it's usually found somewhere around f/8 or f/11. Set it there and adjust the shutter speed and ISO as necessary to fall into line.
Come back next week to for more on photographing artwork. We'll learn from an expert art photographer how he takes photographing artwork to the next level.