Most digital cameras are designed to function as a self-contained unit. Those models at the lower-end are especially so for these cameras typically include zoom lens and flashes that cannot be adjusted. Those cameras at the highest-end however, are a sophisticated light-sensing unit. Seasoned photographers attach these digital "camera backs" to their professional medium format SLR cameras, such as a Mamiya.

Scanning and multi-shot camera backs are usually used only in studios to take photos of still objects. Most of the earlier, primitive digital camera backs used linear array sensors taking seconds or even minutes for a complete high-resolution scan. The linear array sensor acts like its counterpart in a flatbed image scanner by moving vertically to digitize the image.

Many early cameras could only capture grayscale images. To take a color picture, three separate scans done with a rotating colored filter were required. These are called multi-shot backs. Some other camera backs use CCD arrays similar to typical cameras. These are called single-shot backs.