Painting from photographs rather than directly from reality.

Is it alright to paint from photographs? Of course. But you will be producing a different kind of result and it will usually be pretty obvious that it is a painting of a photo. It requires a very 1-dimensional creativity - choosing the paint color.

Joe and I started a list of ways in which painting from photographs is different from painting from reality ("plein air"). I probably already forgot several differences, but let's start a list. These items have some overlap and inter-dependency:

 - Geometric differences: straight lines show up as straight in photos but by eye are perceptually curved away from the center of view, where you swivel your neck or eyes to see away from the center.

 - Foreshortening: lenses usually compress distance, throwing off the proportions of left-right/up-down versus front-back. So the fence posts shrink differently in the camera than from in your eye.  Eg faces are flattened by the camera.  (Perspective is different between an eye and a camera).

 - The brain's processing of 3D, is not the same as the processing of flat 2D photographs. Eg you can tilt a photo and distort the view, but the brain compensates for it. You are painting a photo and weirdly, it is always pretty obvious.

- Colors are different. We can see in the shadows, cameras do not (except "dodge and burn"). The eye's color "gamut" is quite different from the cameras. 

 - In reality, the eye is adjusted to the whole scene. Painting from photos, you eye is adjusted for indoors. In summary: you have a different "white point". Plein air is limited by one gamut, painting from photo is a "double filter", as the original light passes through a camera's gamut, then the eye's gamut.

 - Cameras freeze the action in a way that is hard to do psychologically for moving objects. Consider the wingbeats of a hovering hummingbird. [I was watching sparrows flying, they do little bursts of flapping and pausing with wings closed. You cannot make out the wing and only see a shaped blur. Would I rather paint the blur or cheat and use a photo?

 - Most cameras have a focal plain. The eye can focus back-and-forth. 

These are all physically and perceptually straightforward things. There are several deeper psychological considerations.

When drawing from reality you are actually drawing your minds ideas of what it is looking at. From photo you do not need any ideas. No ideas are required when painting from photo. Effectively, you are painting dots, not things. As a result, painters from photo have no machinery prepared for abstraction or simplification of the ideas. 

Another thing about painting the ideas you see in a scene, is a tendency to reuse the same abstractions, creating parallelism between elements of the scene. You bend the curls of a girls hair slightly to better match the waves in the background - or something like that. It happens subconsciously. In general any subconscious influence will probably be different when painting from photo.

Painting athletically: I am always trying to paint with smooth elegant curves and exaggerated contrasts.  On the one hand this permits me to develop a style affecting more than just color; on the other hand it allows the actual athleticism to affect the result. If I could do the whole scene with one smooth curve, I would give it a try.