How To Photograph A Mirror

Update for 2021: I have a new (short) post, and a video with my updated thoughts on how to photograph artwork with a DSLR.

This is the previous post:
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. Professional studio photographers recommend not using the camera's auto white balance, so I first set my white balance in the camera to 5400K (which is similar to the color temperature of the light given off by my bulbs). I then made a preset in the camera, photographed a group of paintings over and over, and tweaked the color and contrast settings until my painting looked somewhat correct when the image first comes out of the camera.

How to set up to photograph artwork. — My set-up for photographing paintings.

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.

Image of the screen for an X-Rite ColorChecker Passport — X-Rite ColorChecker Passport software screen.

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.

Below are some of my thoughts on photography equipment for painters. Much of the expense of photography equipment is to make sure photographers are able to capture fleeting moments. Since photographing paintings is done under very controlled circumstances, it isn't necessary to buy the best and newest equipment. (I've added Amazon referral links).

The tripod can be one of those cheap $20 plastic ones they sell everywhere. I have a couple that people have abandoned in my studio which I've used in a pinch. The problem is that they can be annoying to move into position. They are normally not recommended as they can wobble, but since photographing paintings should be done via a remote and with the camera in mirror-up mode there isn't any movement. Still it's better to have decent one like those made by Slik, or Dolica they run $50 to $100 (I use a Silk). Manfrotto or Vanguard are better brands and, while they can cost more, a tripod is something one should only buy once.
Proper lighting is inexpensive. I needed lighting to paint after dark in my studio anyways, so I picked up a soft-box lighting set-up with the following specifications: 125W (625w equivalent) Continuous Lighting, 5400K pure white daylight bulbs, General color rendering index Ra > 90. This is the one I have, to give an idea of what they look like. Professional photographers will use flashes which can produce stronger and better quality light, but you can't paint from a flash. Finally, polarizing sheets should be placed over the soft-box, a cheap place to get polarized sheets is Polarization.com.
As to which camera to buy, there are better websites to read than this one. Generally it's considered a good idea to spend more on lenses and save on the camera body. The lenses last longer. I went with Nikon since they seem more interested in high pixel-count sensors while Canon seems more focused on their video capabilities. The recent Nikons have also removed the low-pass, antialiasing filter for sharper images (removing the low-pass filter can put the camera at risk for moire, but art-photographers I wrote to say it hasn't been a problem). For a general idea, a new Nikon entry-level (DX) D3500 runs under $400 with a lens, it has a resolution of 24 megapixels and will take great photos. (You can sell the lens it comes with as you'll need a macro lens). As you move up the line of Nikon's offerings, the D5600 gets slightly better image quality for one third more the price. It also has a bunch of bells and whistles that don't matter when photographing artwork in a controlled studio environment. The same goes for the D7500, which is weather sealed, takes photos faster, has better autofocus, gets better photos in low light, etc. Again, all things that don't really matter for photographing paintings, but which should be considered if you plan on using the camera for other things. Buying a generation behind, used, or refurbished can save money. High-end professional Nikons with a full-sized (FX) sensor (such as the D850) are 36 megapixel cameras and are getting into the range of medium format pixel numbers, and you can find used D800s these days for less than a D7500.
A macro (or micro) lens is normally for photographing small things up close. The reason they are used for photographing paintings is that they have flat field of focus with little geometric or color distortion. They are also generally very sharp lenses which can capture fine details. Painters need a prime macro lens with a fixed focal length, not a zoom. Since I have a small studio now I'm using an inexpensive 40mm micro lens for larger paintings, and a used macro 105mm AIS lens for my sketches. Most professionals seem to prefer an 85mm. The longer focal lengths tend to be better quality, and will have less geometric distortion, but you need more space to shoot larger paintings. A fast, f/1.2 or f/1.4 (expensive) lens isn't necessary as the studio will be well-lit, and the sharpest aperture settings are in the middle (f/5.6 to f/11) range. Finally, because one should focus manually while photographing paintings, autofocus isn't necessary and old used lens can have great (sharp) optics for less money. The circular polarizer should be from a reputable brand (mine is a B+WKaesemann Circular Polarizer).
The color calibration system is one of the most powerful tools in art photography. I have the X-Rite ColorChecker Passport and it's worth its weight in gold. What you do is set the color grid on the easel where your painting will be photographed, take a photo of the squares under the proper lighting, import it into your computer and run it through the X-Rite software. It will make a profile of how your camera sees colors under your lighting set-up. From there, any photograph you take can simply have the profile applied to it and it will get your colors and values correct with one click. I've spent hours trying to fiddle with settings with my painting next to the screen with much worse results. This is really worth the money. I also have a For photo archiving and correcting software I'm using Adobe Photoshop and Lightroom on a yearly subscription. It's quick and powerful when you get the hang of it. The library works very well and I'm quickly able to navigate through my archive of thousands of photos. It has all the standard color correction tools, as well as spot-removal (often meaning bug-removal on plein air paintings). It also has my lens profiles from Nikon, so if I tell the program that's what lens I used, it will fix the geometric distortion, quickly giving me straight lines on the edge of my paintings. To photograph from the computer I tether the camera with a USB cable and control it using the free Sofortbild program in OSX. If I'm using Windows, I use ControlMyNikon ($30).
For monitor calibration, get a decent monitor (I have a Dell U2413 and a cheap 27″ Qnix from Ebay), and get a monitor calibration system. I have the X-Rite i1Display Pro which works with the Dell calibration software. It makes a big difference in viewing your paintings on the computer. TFTCentral.co.uk is great for monitor reviews.