Over the last 35 years I've been a photographer, I started with natural light (as new shooters do). I studied with J. Michael McBride, who traveled the US teaching us how to use it and what to look for. In those days it was a revelation that we could use window light or other ambient light rather than the big strobe units we were hauling around. Film and cameras were slow, so natural light meant using a tripod and holding still!
After I sufficiently grasped those fundamentals, I graduated to reflectors, gobos, scrims, speedlight flashes, studio type strobes, and LED lighting. New shooters embrace natural light because it's free; it's there; and with today's higher ISO cameras, it's easy. But it's rarely the best choice. Most often, portrait subject will have dark eyes, and other unflattering facial problems with uncontrolled light. The problem is that today's shooters aren't learning the basics that we were taught when we joined PPA affiliated organizations. Today's clients also aren't informed about truly professional lighting that could make them look so much better. They see so much of this look on Facebook that they assume it's the best that can be done. It's sad. But as my wife says, I can't save the world.
Anyway, as I learned all the other methods to properly light a face, I pretty much left natural light behind unless it was truly the most appropriate method and it was already perfect. That's VERY rare, but it happens.
And yet... I'm still intrigued by the look of natural light even when it ISN'T "perfect". I've seen some and enjoy the work by the nation's top natural light shooters, and I decided to study it again.
Earlier this week I photographed a super cute girl (Katie) who is always agreeable to be photographed for my occasional tests. I went there HOPING to leave all my lighting tools behind and just go, camera in hand, to shoot and learn more about what works and what doesn't. However, I couldn't resist and brought out a softbox anyway. I'm a creature of habit. But that helped me to learn which is better and why.
I discovered that I prefer ambient light under a few conditions. (And I mean APPROPRIATE UNASSISTED soft, ambient light... not "bad" light.
1) When the subject isn't looking at the camera.
2) When I'm looking for a dark, quiet mood.
3) When I'm looking for an artistic style that wouldn't work with the image being over lit.
One thing against natural light... it often requires more "fixin" in Photoshop.
Here are a few of some that worked one way or the other. Some were natural light only, and some were flash. Lotsa pix. But I think they help to see what I'm getting at.