Not surprisingly, focusing is manual, rather than automatic. At higher magnifications, a separate focusing lamp is required.
Camera shake is very noticeable at high magnifications.
Use of a solid tripod, plus a Remote Switch, is recommended. At high magnifications, the lens focusing ring may not offer the degree of fine focusing needed for precise work. In these situations, a focusing rail is recommended. This allows both camera and lens to be moved together for very accurate focusing on the subject. Autoexposure with the EOS 1, 1N and 1N RS cameras ahould be accurate.