Any modern copy machine will allow you to place a document on the platen glass to make a copy. If you have multiple documents to scan, a document feeder like the DADF or Duplex Automatic Document Feeder will eliminate the tedium of scanning multiple documents and may allow you perform other tasks while the feeder does all the work.
Seeing both sides
There are primarily two types of document feeders, the RADF (reversing automatic document feeder) and the DADF. The RADF, having only one image sensor, scans the first side, then reverses the sheet back to flip and scan the second side. This process, while effective, is slow. Furthermore, the document feeder needs more moving parts to operate. The DADF uses two image sensors (top and bottom) to record both sides of a document at the same time. Since the scanner can read both sides, scanning can be done in a single pass. A feeder using a straight through feed path is likely to have fewer mechanical problems in the future as well. There is simply less to go wrong.
Consider a DADF when you purchase or lease your next copier. It will cost a bit more but gains in efficiency and time saved are well worth the additional cost. At Copiers4sale, we offer the fastest scanners currently in the market place, scanning images at up to 240ipm!