When you take a photograph, the resulting product is two-dimensional: tall, wide, and flat. But in most cases, you want the photo to actually show depth, where images in the foreground and background are all in focus.
In photographic terms, the range of focus front to back is called depth of field. The best way to expand depth of field so more of the subjects in the photo are in focus is to add light. Light contributes to depth of field.
If you were given a photo of people who were the most critical to your success, you’d easily recognize your customers in the foreground in perfect focus. But as you look deeper into the photo you’d notice the images behind that first row increasingly drop out of focus with each receding row. The reason is that for most of the history of the marketplace, businesses have gotten away with having a very narrow customer depth of field.