If you study the reflections in this piece, I think you’ll notice two specific areas that are “unrealistic”:
- The two bright reflections in the top globe. - (Yet…) no reflections at all from the cylindrical portion beneath it.
When an object is “transparent” or “translucent,” you’ll notice that its surface is nevertheless always visible. It’s always got a fair bit of specularity,so you can always see it.
In a photograph, we use “fill lights” to make sure that this shape-defining specularity is always visible. Then, we squirt in just a little bit of “key light” to pull-in details like the globe reflections. Your eye tends to interpret the scene as though the fill-lights were not there… yet, because of them, the amount of key-light can be “turned way down.”
The lighting setup of a traditional photograph is not “real.” Rather, it is believable.