Trying to take in a view in front of us is pretty overwhelming: what dimensions to use, (how big); what to include (that tree's too big); Can I move something I don't like in that position? Questions present themselves before we even start. Holding up a mount of a holdable size helps us to enclose the view and focuses the mind on which part of the area to include. Taking a photograph of various angles enables us to see the view from its best perspective. Don't include everything in front of you. It isn't necessary nor is it practical. Paintings have to include only what is necessary to be interesting and to create the right mood.
If what you are drawing is nearby as in a still life, close one eye to view the subject. You will see the objects in clearer focus, notice the shadows more distinctly, and assess the forms more successfully. In other words, 'squint'. Having both eyes open allows us to see more widely, so we miss the nuances that squinting creates. Your paintings will be more observed, more subtle and more successful.
by Barbara Le Blanc