How can I use paths to draw shapes onto my pictures?
A1:
Choose the Shape tool that's appropriate, and choose Shape Layer on the Tool Options bar. Your shape will appear on a new layer in the foreground color. To draw a custom shape, select the appropriate Pen tool and draw the path you need. After you have placed the path, stroke it or fill it as necessary.
What does the Magnetic Pen do that the other Pen tools don't?
A2:
The Magnetic Pen bases its selection on contrast. This automates path creation to some degree because you don't have to rely on your own hand-eye coordination to follow a complex path.
How do I know what tolerance to set when I convert a path to a selection?
A3:
That depends on how smooth—or how accurate—you want the finished path to be. A tolerance of 1 pixel or less will make the path follow the selection as precisely as possible. A tolerance of 5–10 will give you a smoothed-out path, following your selection to within 5 to 10 pixels.
a. All paths are visible as you draw them (while you drag to set the handles), but the Rubber Band mode makes the path visible as you move the mouse.
Exercises
Start a new page and use the Pen tool to draw a star-shaped path and a freeform path with lots of curves. Stroke both of these paths with a color. Then use the Magnetic Pen tool to trace around them. Notice that as long as you stay fairly close to your original line, the Pen tool places a path right at the edge of the line. Fill these shapes with a color. Draw two more paths inside these shapes, and fill them with a different color. Add a couple of shapes with a Shape tool. Try a custom shape. Practice with the Path tools, adding points and refining your paths until you're comfortable with them all.