A large view finder size 6" x 8" with color isolator to help the decision of the value and color. It comes with a marker pen with eraser helps the artist to render a good composition for plein air painting.
This larger size of View Finder servers with three functions:
1) View Finder with two systems of grids, one third rule (darker set of lines), and golden mean (lighter set of lines).
2) Color Isolator.
3) A marker with eraser for rendering the view on the view finder, and see through it to continue to render the composition to the canvas.
One way to consider in designing your composition, the view finder will automatically divide the scene into three equal proportions both vertically and horizontally. The artist will then be able to analyze if the composition is good, where the focal point would be placed, to study weight of each mass, size and placement, then go ahead to start. General rule of thumb is, it is always safer to place the center of focus near the four intersectional points in order to make the painting interesting.
Courtesy photo by Kevin Macpherson
Examples of how to use the view finder from the same scene, move it around, to find the best choice for high horizontal line, low horizontal line or two third design until the artist can decide for the center of interest as a result by not placing it in the dead center marked "+" in the view finder.
Example1 shown here the subject matter is for Mountains with no horizontal line (or below the selected view).
Example 2: Horizontal line at one third in the design, subject matter can be for the frontal part.
Example 3: The tree may be the center of focus.
The Color Isolator is an inspiration from Mr. Kevin Macpherson's first book: Fill Your Oil Painting with Light and Color, quoted: "The best way to see true color is with a color isolator, holding it about six inches from your eyes, close one eye and position the hole so that you can see the color of the subject area you are judging. This isolator is a small piece of color that you no longer see a thing but only a specific color note. When looking through the color isolator, do it fast. Trust your first quick impression. The color isolator will help you visualize without preconceptions."
The Color Isolator has black, gray and white sections, each with a hole. The artist will be able to judge the color viewing through the holes, make comparison to get the idea on both color and value.