Using the wrong tool usually leads to unacceptable results in one way or another, for example, when a butter knife is substituted for a screwdriver. That was what came to mind when a local artist group asked me if I could save any of the photographs taken of a member’s winning painting. They required a good 8×10 print and a JPG that could be inserted into their on-line newsletter.
The painting was initially photographed straight on, but that resulted in a bright white reflection in the middle from the flash that obscured the painting. The photographer then tried several shots from the side to reduce the glare, but produced unusable foreshortened pictures, by that I mean the closest frame edge was large and distorted and the far frame edge was small.
The photographer tried several shots, always with unacceptable results. That is what I mean by using the wrong tool. A camera with an on-camera flash will produce glare on reflective surfaces and angled shots don’t make for a good documentation of flat artwork because things close to the camera lens appear larger and those farther away become smaller.
The right tool would have been a camera attached to an off camera flash (or better yet, flashes) set away from the painting at a 45 degree angle. Personally, I would have diffused the flash in some way, either by placing some translucent material in front of it or bouncing the light off a large white card or wall. In any case, the light needs to softly and broadly, not sharply, expose the painting surface. The beauty of digital technology is how quickly one can review the image and retake the photo if needed. I also recommend taking several shots at different apertures. For that, the right tool is a camera that one is able set to manual exposure.
When photographing oil paintings or other uneven reflective surfaces I prefer working with slightly under exposed image files. That way I can bring the detail up using PhotoShop without loosing the highlights.
If the next question is “What kind of camera?” my answer will be that it depends on what is the desired outcome. If it is a printed enlargement of the painting, or for reproduction in a book, or the like, the image file needs to be large and for that one must use at least a DSLR (digital single lens reflex), but for a small newspaper or website image a digicam will do just fine.
If there isn’t access to an off-camera flash wait until the painting can be placed in “flat” daylight. Today, as I write, I see out my window that it’s cloudy and overcast. Today would be a good day to have photographed that painting. Place the painting on any support that will allow tilting right, left, up, and down. Then as exposures are made and checked for reflection the painting can be moved around until there is no reflection.
Within PhotoShop there is the means to realign the diagonals of a painting photographed from it’s side, not perfectly, but good enough for the small website picture. The 8×10 enlargement took a bit more effort for fear of distorting the painting’s subject matter. Again, that’s not perfect either as the outside frame looks a bit wonky, but the painting looks proper. The best outcome would have been to use the right tool and make a good photograph at the beginning.