[Chris Saper]

Well, hi Marta, what a fun question.

If were a betting woman (I'm not), I'd say the absense of depth perception is a greater handicap in working from life...when working from photos,you are really just trying to translate values and shapes of colors from one two-dimensional place to another, as the photo is generally quite useless in determining realtive depth.

In both situations though, it's the painter who has to make ultimate decisions about edges, values and saturation, in order to create the illusion of depth.

Chris