An amateur astronomer sets up a high-performance refracting telescope in normal adjustment. The separation between the objective lens and the eyepiece lens is 1.68 m1.68\text{ m}1.68 m, and the telescope has an angular magnification of 797979.
Calculate the focal length of the eyepiece lens. Give your answer to an appropriate number of significant figures.
The astronomer uses the telescope to capture images of a faint dwarf galaxy. Compare the advantages of using a charge-coupled device (CCD) to record the observations against making direct observations with the naked eye at the eyepiece.
