When I wrote about photographing paintings last time, I discussed hiring professionals and the equipment they use. In the years since that post, digital camera technology has developed a great deal and in a direction which works well for photographing paintings.
What an artist needs in a photograph of their work are the correct colors, values, and chroma of the piece, with a distortion-free lens, in a very high resolution which can show the detail in the brushwork, as well as the varying sharpness and softness of the edges. For years the best way to do this was with a medium format camera with a digital back. The price for this equipment could run easily into tens of thousands of dollars. The major recent change in consumer digital photography is that the camera companies have engaged in what technology writers derogatorily refer to as the ‘megapixel war’. This race for better sensors with higher pixel counts has pushed the capabilities of DSLR sensors into the range of the low-end digital backs, potentially saving the DIY painter a ton of money.
Obviously hiring a professional photographer will achieve better results. They will have better equipment and the experience to know how to use it. They are also incredibly expensive (in Italy I paid €100 per photo, or about €1000 for an hour’s work). You can buy a whole set up for the price, and since photographing paintings is really a one-trick pony, getting it good enough isn’t that difficult.
To photograph artwork well one needs the following equipment: A tripod, proper lighting covered by polarized film, a color calibration system and gray card, a decent DSLR body which can be tethered to a computer, a computer with tethering software, a good macro (micro) lens with a circular polarizing filter, and software to edit and archive the work.
First place the painting on an easel with two bright, full-spectrum, lighting sources at 45 degree angles to the artwork, put the camera on a tripod so the lens is parallel to the surface of the painting, as shown below. Lights, painting and camera should be at the same height. There should be no other light sources, and anything white that can cause a glare on the painting should be covered.
Put your calibration card in front of the painting, photograph it, then run it through the included software (if needed convert RAW to DNG with Adobe’s free DNG converter). The software finds the color squares, measures them and makes a preset for your camera. Save the preset. Remove the calibration card and put a gray card next to the painting.
Photograph the painting by first putting the camera in mirror-up mode (or set the remote connection to use mirror-up mode). Set ISO to the lowest number, usually 100, and operational mode should be aperture priority or manual (program mode will work too if you can change the aperture setting). Set image type to RAW. Set the lens to manual focus mode. Turn the polarizer on the lens until the glare on the painting is gone.
Next turn on live-view monitoring in the tethering software on your computer, put the tethered image in full-screen mode, zoom in to the maximum and manually focus the shot by hand. If your tethering software can take the photo in mirror-up mode, shoot from the computer screen, otherwise use a shutter-release cable or remote. Do not use the shutter-release button on the camera as it can move slightly and blur the shot. Experiment with various f-stops to find the sharpest for your lens, normally with a macro lens the middle range from f/4 to f/11 will be best.
Import the photo into your editing software and apply the calibration preset (click the eyedropper on the grey card if the white balance is off). Make any other corrections, i.e. rotation, crop, lens profile adjustment, etc… I then tag the paintings with the year, location and subject, so I can find them easily later. I’ve also made export presets for all the possible uses I’ll have for the photos. It makes preparing images trivial.
Some tips for larger paintings: If you don’t have polarizing sheets, the lights can be at angles greater than 45 degrees to reduce glare. If there are problems with getting an even light across a large painting, find an area with even lighting and take multiple photographs, moving the painting on a flat plane at the same distance from the camera until you have photographs of sections of the whole painting. Then use stitching software such as Adobe Photoshop, PTGui or the free Microsoft ICE to put the individual images together. This method can also be used to get ultra-high resolution images of larger paintings while using a low-megapixel camera. With a bit of work you can capture an amount of detail which would give medium format cameras a run for their money. Subtle HDR is another idea if the value range is too great for the camera.