If you’re sketching without an easel or a drawing table, you have to hold your work at the most convenient angle.
This fellow artist at a sketch group shows an excellent posture for observational sketching from a seated position. She’s comfortably holding the book with her left hand while resting it on her crossed leg.
By holding the book at about 60 degrees, the book remains perpendicular to her viewing angle. This eliminates any danger of distortion caused by looking at the work foreshortened.
By holding the work as high as possible, close to her line of sight, she doesn’t have to tax her memory any more than necessary as she transfers her observation to her drawing.
In fact she doesn’t have to bob her head at all, an advantage when you’re drawing candid poses in public and you don’t want to draw attention to yourself.
Artists who hunch over a work laying flat in their laps make the job unnecessarily more difficult than it needs to be.¬