Q. How do I reference a photographer's unpublished photo?

This will depend on which citation style you are using. Generally, you will want to use whatever rule is used for any other unpublished document. In APA format, according to the Manual (pp. 213-214), you would use the following format:

[Photographs of Insert A. Name]. (ca. year-year). Name of the Papers ( Box #, Folder #). Name of the Archives, Institution the Archives are At, City, State.

Notes:

• See the APA Manual, pp. 213-214, for more examples
• In some cases rules for a personal communication citation might be appropriate for an unpublished photograph.