Maps older than fifty years, or maps in poor condition, cannot be photocopied or scanned. The very strong light needed for these procedures damages them. Non-flash photography, however, can offer very good reproduction and causes no harm to these maps.
A digital camera that offers a higher resolution works very well. It has the advantage of putting the image in an electronic format directly. If you want to view the images on a pc, this is a good choice.
You can also make excellent copies with a regular 35 mm camera and film. Many film processors will not only make prints from the film for you, but will also make a CD with the images in digital form. We scanned the examples here, so there has been some loss of resolution from the scanning process. Still the images are quite acceptable.
We used a 35 mm camera, a tripod, 100 ASA Kodak color print film, and the ambient lighting in the Map Room. The speed and aperture are listed next to each picture.