Painting a plein-air portrait of my niece reading
Painting from life, whether in a studio or plein-air, should always be considered the gold standard for art. Only from life can you see, and hopefully reproduce, the juxtaposition and gradation of values and color that convey the mood of the moment.
When you work from photographs, you are relying on a secondary source of information that distorts the color and value relationships that determine the mood. Most films tend to average the range of lights and darks, making darker scenes appear lighter and lighter scenes appear darker. Digital photography compounds the problems by exaggerating the contrast of details at the expense of the large color and value relationships. To appreciate the levels of digital distortion, try pointing your digital camera at some black object and then compare the difference of values between the image on the screen and the actual object---you'll find that they are three to four values lighter using a nine value scale!
