Barthes writes about photography and the photograph as two-fold phenomena. On the one hand a photograph can be studied as a still image of the way world really was at the moment the photo was taken. Barthes really thought this would be the case, that a photograph presents the real world. He called these aspects of a photograph the studium. This would constitute all the technical information one can achieve from studying a photograph technically and immersing oneself in the photograph. On the other hand a photograph will always have a personal appeal or an effect one the viewer. This Barthes called the punctum. A photograph is something that in a way depicts life as more real than one can remember. Certain anomalies or irregularities on a photograph will have some kind of effects on the viewer. Any peculiar details and uncertanties are interesting and have informational value. These attributes of a photograph can not be studied like the technical details, for example grain, shadows, rhythm, composition, light, sharpness, bokeh, and so on. The punctum escapes all explanations and can not be reduced to a level where it can be studied like studium.
Photograph to Barthes therefore also has a metalanguage just like myths are connotations attached to material or social phenomena. The punctum is a metalanguage, a secondary connotative level that can only be reached in certain contexts. The existence of this level is solely dependent on the precence of a viewer in whom the picture evokes personal feelings.
Archaeologist Michael Shanks has studied photograph as archaeology (see for example http://archaeography.com/photoblog/). To him archaeology and photography have very much in common and they are, in fact, profoundly connected to each other. He calls this hybrid archaeography. In addition to photography being the most widely used form of documentation in archaeology, it holds in it the very notion of archaeology itself. Even when not using photography as the means of documentation the archaeologist is striving to present a picture of the way a site was before s/he got to study it and after that through meticulous studying of the remains try to come up with a reconstruction of the way the site was hundreds or thousands of years ago. Just like for Barthes the studium is a sort of detective work, the process of reconstructing past settings is detective work for the archaeologist. The picture must be studied to the most minute detail and what would be a better means to this than photography.
The object in both archaeology and photography could be long gone. In archaeology, the objective of study is to produce a precise picture of the past. Photography does just that. It provides an objective depiction of the past. This notion relies on the premiss that a photograph never lies. In a sense a photograph is more material than text and text is said to be able to lie whereas the material culture is not capable of doing this. One of the most exciting aspects of archaeology and photography is their ability to represent past settings and events in the present.
This can be seen as a sort of mis-en-scène where the past is portrayed in one single photograph that has in it everything that makes any difference. A photograph in that sense is an objective depiction of the past. Nothing needs to be taken away and nothing has to be added. All the components in the picture have informational value as they are there for no reason at all and for all the reasons in the world. One picture will, of course, deliver only one aspect of the object. One way of capturing the long term change of an archaeological site for example is to go back to the site repeatedly and make a montage or a photocollage. This is particularly relevant when documenting landscapes. To Shanks one of the most important connections between archaeology and photography is the landscape. To him it is the process of looking and arranging things in place.