Guest Blogger: My husband and partner in art business – Rick
Early in the year, I guest-blogged about camera selection and light sources relating to photographing two-dimensional art (here, here and here). I’ve learned a fair amount more since then, and proposed to Ruth a series of posts chronicling my learning curve. I would like to briefly revisit light sources, then take a look at camera-subject set up, and conclude with a short comment about photographing a flat image. Note: most of the photos that appear on Ruth’s website are taken with a Nikon D3100 Digital Single Lens Reflex using the techniques discussed below.
Light Source: This has been the most problematic aspect of photographing Ruth’s paintings; the proper light source has the most profound effect on the color-accuracy of photographic art reproduction. I’ve found that the very best, truest light source is indirect outdoor light. That is, the indirect sunlight that comes through your window and reflects off your white-painted walls. This light seems to have all the colors in the spectrum, and best illuminates the color in art as well.
Setting White Balance: For every different light source in which photos are taken (e.g. incandescent, fluorescent, halogen, etc.), there is a corresponding camera setting for the “white balance.” In short, white balance is the setting for achieving true white-light reproduction for a given light source. This setting affects the entire color spectrum captured in the photo. For indirect sunlight, I began by using the “cloudy day” white balance setting. However, I have discovered that the automatic setting actually captures truer color. It renders a more accurate “white” than any other setting I have attempted, and that includes the sampled light source setting. I have tried many times to use the sampled white balance light source setting, slavishly following the instructions. Result: I have never been satisfied with these photos. No matter what I do with the sample, the photos come out with a blue cast. I experimented indoors with the “shade” setting, with limited success. But the automatic setting for white balance seems to get it right every time. For accurate color and white balance, I concede to the camera’s software.
Camera and Image Set-up: The goal for setting up the shot is to get the camera lens centered on the subject, and parallel to the flat plane of the painting. I shoot the art with it resting on an easel, the camera on a tripod. This can be tricky, because the tendency is to lean the painting backward slightly so that it doesn’t fall off the easel. Unless the camera is adjusted parallel to the angle of the painting, the image will come out unbalanced, with the top appearing farther away than the bottom (or vice-versa), left side nearer than right (or vice-versa). Our easel clamps the painting (mounting board) on the top and bottom and allows me to set the painting perpendicular to the floor. I then set up the camera aiming squarely at the middle of the image: top to bottom, left to right. If centering and parallel alignment are ignored, it is more likely that the image will be distorted on one or more planes. This requires correction in a photo editor like Photoshop. However, the less you have to manipulate the image in Photoshop, the better. If you begin with an image that is mostly distortion-free, you will have a better quality final product. Conversely, the more processing that is required, the less accurate will be the photo capture of the painting.
I want the lens to be completely parallel to the face of the painting, and exactly in the middle. This takes some time to set up. It is important to move away from the set up for perspective, and to look at it from different angles to ensure you have everything square.
You could become obsessive about it, using levels and measuring tapes, but I’m not that obsessive. If it looks right to my eye from every angle, it’s going to be very close. If the image on-screen looks symmetrical top to bottom, left to right, that’s as good as you will get. By symmetrical, I mean that you cannot detect image distortion that makes (for instance) the top wider than the bottom, left taller than right (or vice versa). There will always be a little bit of lens distortion of the image proportions, but you can easily correct this in Photo Shop.
Ensuring a Flat Surface: Did you notice how the edges of the painting aren’t taped down in the first two photos? Note now that there is tape completely covering the border of the painting in the third photo. Those inconsistencies in the flatness of the paper create problems with focus. The paper has to be as flat as possible to eliminate focus problems, and that means securing the edges of the painting all the way around its perimeter, either with masking tape or with a matt and mounting board.
Next time: Using Photoshop to remove Lens Distortion