Traditionally, agencies and design firms negotiate terms and fees directly with the photographer on behalf of their client. The actual license, however, grants rights to the end user of the images — the ultimate client. Estimates and invoices are generally sent to and paid by the agency or design firm, not to the end user. It is a normal trade practice for agencies and design firms to mark up the photographer’s fees, just as photographers mark up services such as models, stylists, and digital services.
When working with an advertising agency, the art buyer is generally the person who vets photographers and collects the quotes on any given assignment. In the absence of an art buyer, the art director or creative director will contact the photographer. Either way, it is important to learn about the client and how the images will be used in order to prepare a quote.
Graphic design firms are frequently smaller operations, and the designer on a given job is usually the photographer’s contact person. Again, you will want to ask for details on the client and how the images will be used to provide a quote.