The lens and eyepiece of Galileo's telescope have focal lengths equal to F1 = 57 cm and F2 = -4 cm, respectively. The tube is pointed at the Sun. A white screen is located at a distance b = 12 cm from the eyepiece. At what distance L between the lens and the eyepiece will a clear image of the Sun be obtained on the screen? What will be the diameter D of this image if the angular size of the Sun is a = 30? Solve the same problem when a Kepler tube is used with focal lengths of the lens and eyepiece F1 = 40 cm, ,F2 = 3 cm, and the screen is located at a distance b = 15 cm from the eyepiece.

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