Portrait of Michelle.
In this portrait of Michelle I cheated by using the perfect lens and camera for portraiture, available at that time. It was a medium format film camera with 4X the surface area of a 35mm, or full frame sensor. The portrait was also done with one of my favorite portrait lenses available then; a 180mm Zeiss f4.0.
I say that I "cheated" because I feel there is a difference that is more than just equivalent f-stops between formats, and is more about focus ramping, and by that I mean that trying to match f-stops between formats is a bit simplistic and it's pretty much impossible to match how quickly focus will fall off between formats even if you normalize the relative difference between f-stops. The formula is more complicated than a simple re-sizing exercise.
But to my eyes part of the charm of this image (for me) is how beautifully and completely the wrinkled canvas (not muslin) background goes out of focus. But it's not a sudden thing; the transition, and that sudden fall off of focus is what I tend to see when people use fast lenses on smaller sized sensors (like full frame or APS-C) when trying to emulate a larger format look. In those shots there is a discernible and more abrupt loss of sharp zone while the bigger formats ramp more gracefully but more quickly from sharp to gone.
For this portrait I used a very large soft box. It was 4 x 6 feet and I always used it in a horizontal orientation and over to one side so the light had more ability to "wrap" further around the portrait subject. The larger light source was additionally softened with several layers of silk that floated in several inches in front of the front diffuser of the soft box.
I use my light modifiers in much closer proximity to my subjects than I have seen other photographer position theirs. The edge of the soft box closest to the camera is just out of frame by a hair. It's also a close to Michelle as I can possibly get it.
Here's a quick illustration:
It's important to me that the face be lit well and that the fall off between well lit skin tone and deep shadow be a gradual effect with no hard lines. I try to get all of the front surface of the light box, or as much as possible, above chin level with my subject so the light under her chin goes into soft shadow and reinforces the line of her chin; the demarcation.
If you look at the play of light across Michelle's face you won't see conventional fall off as delivered from the inverse square law because all of the lit portions of her face are nearly equidistant from the front of the light source. Instead I'm playing with the angle of the light to create a shadow to one side of her nose. You can see that there is no light fall of (diminished intensity) on the lit side, or the shadow side of her face, because in the triangle under her left eye (on the right of the frame) and to the left of her nose has the same tone as the skin on the other side. But the bigger light source is creating a smoother and much more gradual transition from normal skin tone to dark.
The biggest mistakes I see from other photographers who might want to emulate this style are to use too small a light source and/or to position it too far away from the subject which makes the shadow transition more abrupt because there is less light surface wrapping around.
You might also notice that I tend to photograph portraits with the camera as close to actual eye level as I can. This is for several reasons. Lighting people from above makes them seem weaker, subservient or shy and I don't want to overlay a look on someone that isn't commensurate with their nature. The second reason is that "unnatural" angles tend to amplify the forehead and reduce the size of a subject's chin, which I find unflattering. What I imagine for most of my portrait sitters is what they would look like if we were sitting in a Starbucks or a café and we were looking at each other across a small and comfortable table. I'm only 5 foot 8 inches tall so I don't usually tower over most of the people I shoot. But I feel strongly that eyes at the same level as camera is the most natural and intimate way one can photograph a portrait sitter.
You'll note that I have a black panel positioned on the opposite side of the subject from the main light. This keeps stray photons from bouncing off the ubiquitous white walls of modern civilization and bouncing back into the shadow areas to undermine my beloved shadows. You may call it subtractive fill but it's just there to block stray bounces.
On the other side, just behind and out of camera range and behind my subject, is another black card which keeps excessive light from the main light off the background. I don't always need a black card there if the distance from the foreground to the background is 20 or 30 feet away but the closer the main light is to the background the more I want to subdue light coming past Michelle and degrading the shadows that edge the background.
The background almost always gets its own light and it's usually a small soft box with a light head that matches the color temperature and flash duration ( I like long duration flash, actually) of the main light.
If I want more undulation in the background I use the background light at an angle to the background instead of straight in. If that's the case I might also use a net to even out the spread of the light from one side to the other. The shallow depth of field from using the correct portrait camera and lens takes care of smoothing out what would otherwise be distracting glitches in the background.
In the days of film I would generally have the shoulder closest to the light be a little lighter than the rest of the subject and that would require me to burn down the tones in the region under the enlarger in the darkroom. I think I did a decent job blending the tones in this image of Michelle. It works best if there is always some detail there to begin with. Burning detail-less highlights generally just looks like shit.
None of the things in the illustration are hot glued to the floor at the beginning of the session. We're moving stuff all the time.
Many years ago I posted a time lapse video of me shooting a portrait for advertising at Zach Theatre. There was a giant scrim, I lit with hot lights, and there was a big, passive file on the other side --- but pretty far away (I want those shadows). I needed some fill because the space we were shooting in had black walls! Anyway, the time lapse covered the time spent shooting one person. I could count 25 times, at least, when I stepped away from the camera and made adjustments to the lighting, to the fill, to the background light, etc. I guess what I'm saying is that portraiture, done the way I prefer, is not a passive process in which one only stands stationary and barks commands to a compliant model.
When I feel it's needed I get in front of the camera and even mimic to my sitter what I'm looking for. It's easier for people to SEE what you imagine than to try and explain it to them in hundreds and hundreds of words.
This is just the way I like to do portraits. You prints will vary.
distillation: big lights, big modifiers, get everything on the front side of the subject as close as possible. Keep the background as far away as possible. Control the highlight to mid-tone to shadow transitions as you see them aesthetically. There is no "ratio." There is no formula. We work on a clean slate for almost every shoot.