This time, the image distance v = 2f = 20cm, then the light screen is located at the location of the figure at point D.
(1) the convex lens is placed at point C, as shown in the figure.
(2) by the convex lens into a real image of the dynamic law: into a real image, the object distance becomes larger, the image distance becomes smaller, the image becomes smaller can be seen, when the candle moved to the 20cm scale, at this time, u = 30cm, the object distance increases, the image distance becomes smaller, so the screen to the left in order to get a clear image again.
When u>2f, into an inverted reduced solid image, the camera is made using this principle.
The answers are: (1) 10; D; (2) left; shrink; camera.