In academia, photographs are not just considered an acceptable primary source; they are an invaluable one. Archaeological research often destroys the item that it uncovers, and the only way these artifacts are preserved is by taking a great many photographs. Even before archaeologists had access to photography, they drew pictorial records of their findings. Once photography was readily available it became standard procedure to photograph everything.

Archaeological digs are broken down into a grid pattern.
This makes it easier to record the locations of various finds, and are carefully dug down a single layer at a time. Each layer is carefully photographed before the next layer is removed. Artifacts, even if they can be removed without being destroyed, are photographed both before they are removed from the ground and, if possible, after. Pictures taken of the artifacts still in position in the ground have an arrow indicating North, and both pictures in the ground and after they have been removed are taken with rulers to indicate scale. This preserves the evidence of where the artifacts were found in association with each other before being moved.
Artifacts do not always survive and photography preserved them.
While archaeologists attempt to take pictures of artifacts from multiple angles, depending on the fragility of the artifact that is not always possible. As a result, many archaeological conclusions are based on evidence that was either destroyed as part of the excavation (for example, evidence of long rotted wooden support beams for buildings), destroyed when they attempted to move them (i.e., an intact beaded netting on an Egyptian mummy—the threads holding it together disintegrated when they tried to move it), or have since then been lost because they degraded when exposed again to light and air.
Even in museums today, with their climate control systems and careful lighting, artifacts do not always survive. So these photographic records, many of which are now available via the internet, are essential tools. While the photo may not reveal all the angles like you might get if you could actually handle the item yourself (assuming you even had that option), they are unfiltered, unmodified records of extant artifacts, and are as such considered vital primary sources.
Sometimes in our zeal to find answers, to teach people about history, it is extremely easy to get lost in the minutia of exactitude. While it is actually impossible to know 100% what an object found is for, its use, or how it was made, we can take a lot from the photographs of these artifacts and use that information to help reconstruct the items in our minds and on paper. Understanding that the photographs of artifacts are indeed Primary Sources, can expand our research horizons and allow us to delve deeply in to the amazing world of research right from our computer screens.
Happy Researching!
RoseAnna
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