You need a reference on plain logic?
The idea is to make the subject stand out of the background.
Plain logic really.
What is it exactly you are disputing?
Since you keep coming back to this, yes! In most cases, you want to seperate the subject from the background. But there are as many ways of doing that as there are photographers.
As Erik said, hopefully, on this website, as learning photographers amongst each other, thinking out of the box should be promoted. I hope to learn from others on here by looking at what they do differently from how I approach my images.
With that in mind, logic hasn't always been the same when it comes to imagery of any kind, nor is it uniform across the globe. Different cultures address the subject in different ways. Again, "thinking out of the box" is a wording that comes to mind, but the question is: What or who exactly determines the outer boundaries of said box?
150 years ago, subject seperation was already well known through painting. There were many ways of achieving this. About 100 years ago photographers started experimenting with techniques used in painting, and techniques plain impossible in classic painting, to set their subjects apart from a background. They did not use f1,4, nor did they rely on dark(er) backgrounds in all instances. Which brings me to:
Please read carefully:
You need separation between B/G and subject.
You could have the subject back lit (obviously front lit as well just in case you wish to query that part as well), you could have the B/G lit, you could have your light as close as possible or further away to the subject with or without a grid and/or the subject further away from your backdrop, you can have a combination of these. There are many more lighting techniques and lighting set ups and iterations and I wonder why I even bother state the obvious!
That's contemporary standard thinking on the topic of portrait photography. It hasn't walways been that way, nor does it need to be the golden rule, or even a rule of thumb. By copying others, you can learn a lot, but just as much can be learned from leaving that path and trying to find out for yourself whether/why other scenarios do/do not work for you. I have in mind a brilliant portrait of a black man on a chair (full body portrait) with his hands folded together in front of his face. Lighting was achieved with a single standard lightbulb at a 45 degree angle from above, but at the same height as the subject. (I will link to the photo if I can find it again). All I can say is that the photographer made this "out of the box"scenario work really well for him. I even believe this photo was of a celebrity and he didn't need to hire his model.
So closing with:
I am an avid learner. First Lemonade and then Black on Black.
Hang on to that thought. But think further. If you want to learn, why not learn from others by accepting that they do things differently? I'm not a fan of Bjorns UV work because the color rendition just doesn't work for me, but I still watch his photo entries with interest, because I might find a scenario where I could make this technique work for me. I try to be an avid learner too, and I would find it a real shame if everyone would stick to these "rules of thumb" because it would mean that every portrait would look more or less the same.
Agreed, the learning curve wouldn't be as steep, butthe outcome a bit bland in my opinion.
Now I want to try my luck at painting my girlfriends face an even, neutral grey, ask her to lie down on a bed of even grey pebbles, maybe cover half her face with an even grey scarf and take a portrait at f16 or f32 to see how I can make that scenario work, using a single lightsource from an angle about 60 degrees behind my back. There are just so many interesting scenarios to explore here. The human mind is capable of more then being fooled by simple trickery. The shape of a face, facial features, eyes, mouth, nose. Each of those can be enough to seperate a portrait from a background because these shapes are engraved in our brains. You just need to remove enough external references to make them stand out enough.
Maybe there is a rule I try to follow in my photography. If the intent of a photo is not clear at first glance, there is too much information. Reduce external references until you bring across the point....
But then again, there are plenty of good photos, and even famous photographers, who intentionally break with this rule and make it work for their photography.
