This past week, a student brought up the dilemma we have all faced at one time or another. That is getting our field sketch or preliminary thumbnails in the same proportions as the final painting.
The ViewCatcher is an extremely handy tool to aid us in siting our composition. I slide the inner panel to align with the premarked canvas sizes on its outer frame. Then looking through the window I can see how the scene will “fit.” Once I decided on a size and view that workes I lay the viewer onto my sketchbook and trace the opening (middle image).
But taking it a step farther using a trick from design school days, I now draw the same picture plane outline with the ViewCatcher but I use an diagonal extension to enlarge my box to a more workable size. I extend a vertical and horizontal pair of lines and anywhere they meet on the diagonal is a proportional picture frame. The dotted lines in the right image above show what I am talking about.
Of course this is all usually done in pencil so I can erase the original box and get to work on my compositional shapes, values and notan. Below you can see an example, but this time I left the original box so you can see how handy it is to work just a bit larger, than to be confined to such a small picture plane.