There are many portrait lighting setups, and beginners can be confused about how to start with formal portraits. If you will only use one speedlight on the camera, then there is no doubt that what you need then is Bounce Flash. It's easy and can be very good lighting.
But this article is about more formal portraits with multiple lights (at least two, for Main and Fill). One poor way (but probably how we all start with fixed lights) is with equal lights just placed on each side of the camera, which is very flat lighting. But Flat is Not the goal for individual portraits, it is uninteresting portrait lighting. This article would have really helped me to understand the ideas of getting started back then, and now after several years, I can point out one good and Easy Standard General-Purpose 45 degree lighting starting point. An incident meter for flash will be extremely useful for setting each light precisely (see the Sekonic L-308 article, but just the Inverse Square Law method could be helpful). This is like an easy formula about basics, which may be all you ever need.
This article goes on and on with more detail below, but first, here is a brief setup summary, which might be enough if you have a bit of experience.
That’s about it. There are other choices, but this is a very adequate general-purpose portrait setup. The mistake you should NOT make is two lights simply placed either side of the camera, which is NOT a main and frontal fill concept. And if they are equal intensity, that’s flat lighting and normally worse. The presence of fill’s dim shadow gradients is intentional to show shapes and curves, to add 3D.
For multiple lights, I use a light meter with manual flashes and optical slaves, which works great indoors. And a PC sync cord to the fill light to trigger them. The fill light is very close to the camera tripod, and already aims at the others.
Continuing with more detail. This standard setup always works well for me. Using a flash meter makes setup very easy and repeatable, and you know exactly what you’ve done then. That might include TTL (Commander TTL meters the flash too, for Main and Fill levels). But the background and hair lights are impossible to meter with TTL and need to be a manual light system instead.
This case shown uses four lights, Main and Fill, and the background and hair lights (which can be optional, but they do help). The article is about Main and Fill light. These used here are studio lights, but speedlights in umbrellas do this well too.
It is a classic setup. Traditionally, the main light is placed up to about 45 degrees high and 45 degrees wide, meaning higher than eyes and somewhat to the side as viewed from the subject. The results of the individual lights are shown below. The main light will make intentional shadows on the face (but it is large and close, to be softer). The fill light softens the main light shadows to become very natural gradient tonal differences to show shape (is Not flat lighting).
Portrait lighting is about intentionally creating the presence of these natural gradient tonal shadows. What we call "seeing" is about awareness, recognizing these tones that we can see if we just think to look. We can't create well if we don't yet see.
For the idea, see the pictures below with only one light lighted at a time.
The actual main and fill concept is that the best fill light theoretically is located very near the camera lens axis.
For that purpose, the fill light is often placed behind the camera, centered higher looking over it (maybe a bit higher than shown, so your head at the view finder blocks less of it). The idea is the fill light lights the same view that the lens sees so that it lights the exact shadows that the lens sees - but specifically prevents making another second set of shadows. Anything else is probably just two lights. If directly above the lens, any shadow behind the subject is well hidden by the subject (which is exactly what flash brackets do for flashes on the camera). The frontal fill is a flat light (no shadows on face), so it doesn't really have to be so large and soft since it makes no facial shadows to be softened anyway. Behind the camera does require more length in the room, and more fill flash power (more distance). There are a couple of ways to do this... one way is the fill light behind the camera, as shown at right.
Or the fill light can be close in front of the camera (shown next below). It must be well back near the camera so the camera lens can see around its umbrella. The fill light used below has its fabric edge nearly touching the lens barrel. The point is for it to be frontal, literally about as close as possible to the lens axis. Slightly to the side means it may make thin shadows, but being a large umbrella minimizes that greatly (more distance to a lighted background also helps). This front method works well in a cramped space and is closer to the subject than if behind the camera which also helps the flash distance and power. Do use a lens hood, and check that your fill is not shining into the lens (and that the hair light is not either). It's hard for me to see much practical difference between these two ways, but the extra added shadows are detectable in the individual sample below.
Ignore the decor, the furniture is all moved out of the way just enough to fit this in. I always need an absolute minimum of at least 15 feet depth for this setup, which will still be Extremely Cramped. 20 feet will be Very Greatly Better (it need not be very wide at the camera end).
Never get the camera too close, always stand back a little. The camera here is at about ten feet from the subject. Perspective IS NOT about the lens focal length. Perspective is only about the view seen from the spot where the camera stands. Perspective is what you see from the distance that you look from. The focal length may make us choose to stand at that spot, but standing there offers only the one perspective view that is available there. Any lens can only see what is seen when standing there. Regardless if its a group shot with a wider shorter lens, or a head shot with telephoto, you want the camera standing back at least 6 or 7 feet, and 8 or 10 is better. Zoom in all you want, or use any lens focal length, any way that gives the view you want, but always stand back some for proper perspective.
Some imagine a portrait lens means f/1.8, but you’d never suffer with f/1.8 in the studio. A 105 mm lens was always called a "portrait" lens in the 35 mm film days, simply because it requires a typical portrait view to stand back at a proper distance, forcing proper perspective. For example, a 105 mm lens on a 1x sensor at 7 feet has a field of view of 1.6 × 2.7 feet (portrait orientation). The equivalent focal length on a 1.5x crop sensor is 70 mm, which at 7 feet also has a field of view of 1.6 × 2.7 feet. These portrait shots here are at ten feet with f/10 1/200 second ISO 200, Nikon D300, 70-200 lens, 80 mm 1.5x DX (which is 120 mm for full frame equivalent), and they are cropped a bit. Use the focal length that gives the view you want, but always stand back sufficiently for perspective.
This background here is about 8 feet behind the subject, which is very ample space, even feels luxurious. It can be important, because
The spot of light on the floor here is just the backlight reflector's hole for an umbrella shaft... we might always notice where it is aiming (about the hair light too).
The Main light (40 inch Large Alienbees softbox) is set close, about 32 inches from the subject's face. The rule of thumb is that if the distance is not much more than the light's size, its light will be acceptably soft. This softbox is an Alienbees B400 flash (160 watt seconds) metered to f/8, which is set halfway between 1/8 and 1/4 power level (ISO 200).
A white umbrella works fine on the main light too. There is no difference in the light (softbox vs umbrella - because both are "big"). The umbrella has the light stand in front of it, keeping it back a bit farther, maybe 48 inches to the apex of fabric (but close as possible, so the light stand is still out of the camera view). I prefer a reflected umbrella (vs shoot-through), and white is best for people (Silver is more specular, white is more diffused. Silver is good to make furry pets sparkle more). A shoot-through umbrella has a terrible rear spill, which can be relatively minimized if it is very close to the subject (the umbrella is very close relative to the rear wall reflection path so that the distant wall reflections become insignificant). Shoot-through also has a central hot spot, so feather it a bit (aimed at a point a foot out in front of the nose, to avoid a hot spot on the face). There is absolutely nothing wrong with umbrellas. The light on the actual subject is the same from both (it depends on the “size” of the light, and the distance). Softboxes have less spill and are simply convenient to use (but not to assemble or transport), but the light is the same - spill and shape of catch light in the eye are the major differences (shape of the umbrella vs the rectangular panel).
The Fill light (45 inch white umbrella) light stand is about 8 feet from subject (because camera is back so far - back close to camera so camera can see around it). Its fabric here is right next to the lens. Near as possible to lens axis (opposite side from main if not centered over camera) - idea is to light the same shadows that the lens sees. Do use a lens hood, and check that your fill is not shining on the lens. Hair light should not shine into lens either. Because it is relatively far, maybe use your strongest light as fill. This is a Alienbees B400 (160 watt seconds) metered to f/5.6, nearly 1/2 power at this distance. (A later addition - I added an Alienbees 64 inch white PLM umbrella for fill, which is huge, but out of the way behind the camera, and it fits under a ten foot ceiling. I like it but am not sure about it - It spills very much light at 180 degrees, but hasn't been a problem. It is about 1/2 stop brighter than the regular smaller umbrella, good for the greater distance).
The glare in lower left corner is the background light, on a short stand, hidden behind subject. Hair light is shown above, this one on a short mini-boom (and counter-weighted, and on a heavy stand). Both of those are Alienbees B800 (320 watt seconds), only because I bought B800 first. But it turns out, I like the B400 power much better for ISO 200. Half power is one stop - so 160 watt seconds at ISO 200 is exactly the same situation as the 320 watt seconds others see at ISO 100. Both have a wider reflector, but this background light has a 40 degree grid, and the hair light has a 20 degree grid, which knocks their power down. Color balance is less critical back here. Power depends on distance and effect sought. These B800 with grids (ISO 200) are Background light at 7 feet, maybe 1/8 to 1/2 power. Hair light at 5 feet, maybe 1/8 to 1/4 power. A little stepladder to aim the hair light is visible (the modeling light allows aiming it).
Speedlights in 45 inch white umbrellas can do the same thing. Speedlights can easily do background and hair lights too. Optical slave mode (Nikon SU-4 mode or Chinese S1 mode) is extremely handy for manual flash. Foot mounted optical slave triggers can be added to speedlights, and they work, but the internal slaves built into flashes are more sensitive (they have battery power). Nikon Commander can do TTL, however the Commander can only individually control two or in some cases three remote lights.
When in the same umbrella, the Nikon SB-800 at 24 mm zoom meters a full one stop less power than the B400 (a SB-600 or SB-700 might be about 1.4 stop less than a B400). The SB-800 flash in umbrella as Main light, zoom at 24 mm, ISO 200, meters f/8 at 1/4 power + 1/3 stop when at 24 inches to stand pole and 50+ inches to umbrella apex fabric. SB-800 Fill light back with camera, meters f/5.6 at Full power at ten feet to fabric apex. That would be a distance limit, and speedlight full power is a slow recycle, but it does the job. Speedlights are internally focused, and 24 mm is better in umbrellas than in softboxes (studio lights are bare bulb inside softboxes, but speedlights cannot be bare bulb). There is absolutely nothing wrong with umbrellas, they work like magic. Soft light is only about large and close.
Power Summary: It depends on your setup and light placement. Regular size full powered speedlights will work for umbrella portraits, but are a stop or two less power than normal studio monolights. If in umbrellas, speedlights will be near maximum power, which means slow recycle, which can be a problem when you want to go faster. We have to wait on our slowest light. Better studio lights at 1/4 power can have immediate recycle (and are fan cooled to make use of it). The recent numbers below are a little different than above, due to different setups. But for example, numbers for my previous session December 2015 are below, for single portraits but some doubles in same setup.
These studio flash recycle fast at the lower power levels, and have fan cooling. Shooting real fast, click, click, click, is no issue, but I only do that at the instant when the subject is really sizzling. These have more power available for tougher situations. Bigger lights are slower recycle, and just have to be turned down more, but they don't turn down a whole lot more, and I think stability and color are better if not at minimum. Operating at midrange or higher power seems best. 2x power rating adds one stop of exposure. These lights are ten years old, and one was repaired once (only $40 at Alienbees), and still going strong.
My opinion is that 150 watt seconds is obviously very adequate power for home portrait situations at ISO 100. The only reason I have a couple of 320 watt second lights because in the beginning I was told they were the right choice, but maybe that’s a bit much power for a ISO 200 camera. I soon bought a couple of smaller ones, and wish I had all four. If working outside in bright sun, or if lighting up the basketball court, then you need much bigger, but that is a second set, as the bigger ones will be a struggle with home portraits.
1:1 is very flat lighting, shadowless, special purpose (copying paper documents, or might be used for High Key). A one stop 2:1 ratio is often excellent in the general case for color portrait work (Main light metered to be one stop stronger than the Fill light, at the subject). You should experiment with ratio to learn your choices (B&W work needs more contrast, and 1.5 stops is good for portraits, or even 2 stops but which is becoming a lot, dramatic). Ratio increases image contrast. If the fill light is weaker (greater ratio), the final shadows will be darker and more dramatic contrast. If the fill light is brighter (more equal), the lighting is more flat and nearly shadowless (the flat frontal fill fills and hides wrinkles better too). A one stop ratio is a good general compromise for color photography. Experiment plus or minus on fill power, and when you find a result you prefer, metering it measures the ratio so you can easily set it up next time. You will soon learn to think in terms of the appearance of that final shadow (ratio).
Complication: Existing ambient light and/or spill light weakens the ratio. If considerable spill (for example, shoot-through umbrellas are terrible about spill, 2/3 of the light goes out the back), which is reflected back from near walls, affecting ratio. Less spill, and from closer lights and farther walls, produce more accurate ratio numbers.
Eliminating the ambient light: Existing ambient light indoors can spoil the intended lighting and cause mixed white balance, but indoor ambient is dim compared to the flash, and is easily eliminated by using low ISO, maximum shutter sync speed, and a moderately stopped down aperture (like f/8 on DSLRs, which also improves depth of field on the subject). Then to prove it, a test photo with all flash trigger disabled is a totally black picture. Meaning, all ambient is shut out, simply gone now, so no white balance problems either. But the flash power is set to meter correctly.
The example above is a f/8 main and f/5.6 fill, which is 2:1 power and a one stop ratio, but is also called 3:1 "lighting", which is good for general-purpose, and good for general color work. It is mild contrast, there is no obvious dark shadow left in the final picture, yet sufficient gradient tonal shading does still remain, far from a "flat" light.
Note that there are two different schemes used to state lighting ratio. The same one stop ratio can be, and is, called 2:1 power ratio or 3:1 lighting ratio, and different sources may say it either way, so we always have to read more words to know which ratio is being discussed.
Power Ratio = Main : Fill is convenient and popular, it's how we can measure and setup the lights. I call it Power, because we set thr power level in our flashes for that result — power is what we can directly control. It's the ratio of lights themselves (metered at the subject). We double the flash power to increase the light by one stop. If the main light is set to meter f/8 and the fill light is metered to be f/5.6, that is power ratio of 2:1, or one stop.
However, the same setup is considered to be a "lighting ratio" of 3:1 (by definition, this 2:1 power computes 3:1 lighting, because 2/2 main + 1/2 fill is 3/2 on the highlights (main plus fill), and only 1/2 on shadows (fill only), which is called 3:1 lighting ratio). We find it easy to meter both lights, but difficult to meter the highlights and shadows on the face.
Lighting Ratio = (Main + Fill) : Fill is the actual lighting we get then (the intensity result at each part of the subject, which is somewhat theoretical since we don't actually measure each area). The concept is that the highlight areas see both main and fill light, but the shadows see only the fill light. The larger number on the left side of the ratio is simply +1 greater for Lighting ratio than was computed for Power ratio.
Usage of the two terms gets confused. The point is, there are these two systems of nomenclature, perhaps the technical (lighting ratio of the actual light), and also the more practical (metered ratio of the power). The popular lighting books you read may use either system. Many lighting writers today say Lighting Ratio, but use and mean Power Ratio (because that's what we can measure). We have to read closely to see which they actually mean when they say specify numbers of ratio. Some will call a one stop difference to be 3:1 (lighting ratio), but may call it 2:1 (power ratio). You can learn to simply see this ratio result in their pictures they show (beginners are advised to look and notice and stop and think, because ratio is very important to portrait lighting). This may soon interfere with your watching television. Instead of wondering who the murderer is, you may be pondering lighting ratios. Esp in the older movies, the close-ups of the big stars were extremely controlled.
The fill flash calculations are shown in this table (Fill relative to Main). The Fill light is 0 EV when metering it matches the Main light, and is then entered as -EV difference from the main light.
Relative to Main
|0 stops, 0 EV||1:1||2:1||200%||50%||1 EV|
|-1 stop, -1 EV||2:1||3:1||150%||33%||0.58 EV|
|-1.5 stops, -1.5 EV||3:1||4:1||135%||26%||0.43 EV|
|-2 stops, -2 EV||4:1||5:1||125%||20%||0.32 EV|
|-3 stops, -3 EV||8:1||9:1||113%||11%||0.17 EV|
|-4 stops, -4 EV||16:1||17:1||106%||5.9%||0.09 EV|
Technically the 1.5 stop rule of thumb really must be log₂(3) = 1.585 stops to compute the 3:1 power and 4:1 lighting, but convention does call it 1.5 EV. But 1.5 is close to 3 and 4, minor in the scale of things, and the other choices are precise. There is a calculator for this that includes third or half stops.
Overexposure: The Overexposure column is the amount the sum of the two lights exceed the brightest. That may be important when the brightest is the ambient with TTL fill flash (and the cameras metered settings represent that ambient), but for studio Main/Fill situations, after setting up your lights for the intended ratio (setup metering is done individually, with one light turned on at a time), then turn on Main and Fill lights together to meter for exposure. It may be about 1/2 stop brighter than the Main light only. If that f/stop number is higher than you might want to use, then start over with the main backed off a bit, maybe 1/2 stop lower. The background and hair lights should be Off for that metering, because they do not (should not) affect exposure. You can do this setup before the subject arrives (however, the hair light will need double checking then, due to the effect on hair color). Other than creating nice lighting, one advantage of this system is that setup by metering to control the lights ratio will perform again next setup time in the same way.
Contrast: Greater ratio is contrast (darker shadows, greater shading. The shading better defines subject shape and curves). This is desirable in some degree, but it can be too much. IMO, 1.5 EV is plenty of ratio for color portrait work (often uses 1 EV, or less for softer photos). Others say 2:1 or 3:1. It's a choice, but commonly, children less ratio, women a little more, and men more ratio. Experiment some, and see and learm all the choices. Do realize that ratio is a tool, a control that your lights can easily change. Colors can generally provide the contrast, but B&W grayscale needs and can use more ratio and contrast. Ansel Adams said (of grayscale work) that pictures always need some area of true black, and also some area of true white (this contrast range really aids grayscale). The Levels tool is good to do that for grayscale. But too much tonal contrast can be less pleasing for color work.
One stop or so difference (fill less than main) is a good general-purpose ratio for color work, but B&W grayscale can benefit from greater contrast than color (maybe up to two stops sometimes, maybe just for men, but it can be too much for color). It is your choice, whatever you want to create, but do realize that ratio is a very important lighting tool to be used. Beginners seem to start by just setting equal lights on either side of the camera, with the notion that a flat even light (1:1 ratio) is best, and there may be situations it is, but a little ratio really makes a big difference in a portrait. It is a fundamental for portraits.
Note a ratio only has significance on ONE face. You do Not want to create a ratio across a group of people, because one person on the end would be closer to the main light then. Groups need an attempt to light all of their area evenly. Even for couples (a tiny group), a large light slightly more distant can be more even, but if faces are turned toward each other, a ratio likely means the near face gets broad lighting, and the farther one gets narrow lighting. The big need is to us to learn to recognize what we see, and then to do what we want to see. But larger areas need more even lighting. Lights on each side of camera lighting the two sides of an area is NOT a main/fill concept... it is two lights (not necessarily bad if the plan is to evenly light the area). But even for a large group, lights near each edge, aimed in toward center, may be very even, but the lens (in the center) sees terrible shadows, shadows of the front row on second row. Faces that "can see" the camera" may still be in shadow. But a solution is both lights at center near camera, aimed outward (minimize any overlap in the center), which then lights the faces the camera lens sees, which can be of advantage.
TTL: TTL is not suitable for metering background or hair lights, but can work for just Main and Fill. Or speedlights work fine everywhere if in Manual flash mode (and mount much easier in umbrellas than softboxes). TTL can work for Main and Fill if you can compensate them individually, like with the Nikon Commander, but the Commander requires all lights use the Commander system. See more detail about the Nikon Commander system. Frankly, with more than a couple of lights (Main/Fill), multiple lights just work better as manual lights all around, much easier to control (with a hand-held flash meter).
For just Main and Fill, the Nikon Commander is almost point&shoot. Set the Main group to 0 EV compensation, and the Fill group to -1 or -1 1/3 EV (or Main as +1 EV and Fill at 0 EV often seems better exposure for me). Or a way all four lights could work is a speedlight as Commander on the hot shoe with itself as Fill, TTL at -1 EV, and group A as Main, TTL at 0 EV. Group B as Background, Manual with power as required (behind subject might block Commander access.. somewhat to the side, or low on floor might allow access under the seating), and Group C as Hairlight, Manual with power as required. The Commander may suffer some limitations, and FV Lock is often needed to prevent pictures of the subject blinking. But still, the Commander works well for two umbrellas in the living room. It is extremely convenient, extremely fast to set up, for a couple of lights. As always, the best TTL tip is to realize that Flash Compensation is the necessary tool to get the TTL exposure perfect. If it is not quite right, simply fix it so it is.
Trying to cover too many high spots here, but camera TTL is reflective metering, and the hand held flash meter is incident metering. If photographing a white dress or a black dress, reflective gives very different readings, and tries to make both come out middle gray. Which is just how it works. But incident metering does not see the subject, and it instead meters the actual light source, so that any subject comes out about right in that light. Incident must be metered at the subject's position aimed at the camera, not at the camera position aimed at the subject. If you’ll be doing much of this, you will very much enjoy the hand held incident meter.
Main light only (also called Key light). Placed at up to about 45 degrees high and up to about 45 degrees wide, from the subject. Here metered at the subject to set it to f/8 (exposed at final f/10 here). A large softbox should be positioned "close", 30 or 36 inches from subjects face, subject might reach out and touch it. Large and Close is what creates Soft. Soft means the shadows are very diffused, NOT sharply defined.
Or - a normal reflected umbrella main light should be "close as possible" (subject can reach out and touch the light stand pole - maybe two feet to the light stand pole, maybe four feet to the umbrella fabric - just out of sight of camera).
The angle of the main light makes intentional shadows, natural shadows, still strong and dramatic here, but which the fill light will subsequently greatly lighten, but will still leave mild tonal gradients - intentional tonal sculpting which shows shape of the subjects curves. Natural lighting, not flat frontal light.
The Main light is high (nose shadow should point somewhat downward), but not so high to cause shadows in eye sockets. The eyes should be well lighted. Watch the catch lights in eyes too. You definitely want catch lights (sparkle, liveliness), in both eyes, and positioned well (upper left or right). I do tend to put the main light too low, but at least the center line of light is above the head.
Subject's shoulders angled about 45 degrees from the camera into the main light (narrows the body), but her face almost towards camera, and eyes at camera (no strict rules, there are other choices too). Subject turning their head will change things, not necessarily bad, but not optimum 45 degree lighting then. Ideally, main light should always be about 45 degrees to the nose. If you are going to work with head at another angle, the idea is to move the main light so it is 45 from the nose. You'd do that if seeking one specific shot, but I don't move it when the subject is trying all sorts of poses.
See the far cheek? It is important that some light hit it. The nose shadow is the root of many lighting styles - which roughly are:
Rotating the head away from the main light can change open loop to Rembrandt. Rotating the head into the main light shifts towards butterfly. When setting up, and when analyzing your results later, remember to think about where is the nose in relation to the light? This is a key element, and 45 degrees is a good answer. We might choose to worry more with the nose shadow, but I don't. “High and Wide” and "Some light on far cheek" works well for me. The session may be dozens of images, and the subject is turning, so it is not static anyway.
See the dark side of face? The fill light will have that covered. The point of 45 degree lighting is to create natural shadows (frontal light does not, is "flat"). Shadows are intentionally added by the side angle, to "sculpt" or show the curves and shape of the face, subtle gradient tones to be interesting and natural (the fill light makes them be subtle). This shadow shown is called Narrow Lighting, near side of face is dark, which makes a face look more narrow, thinner. Subject facing away from main light is Broad Lighting (dark far side hidden then, only near bright side seen - a fully lighted face, looks wider). However, the body can still face that opposite direction, with face back at camera, enough to be Narrow.
Simply metering the lights is the easy way to setup, repeatable from last time. If doing this without a light meter: Start with only the main light on, and tweak manual power level and exposure. The result will show the dark side shadow, which you want, in some degree. The purpose of the fill light is to lighten that shadow, so add frontal fill light and adjust its power level with that final criteria, for the fill ratio. Not too much fill - half intensity of the main light, or slightly less, leaving some obvious slight trace of that side shadow. This added fill will correct the underexposure too, another criteria. Make it look like you want it to look, but avoid a flat look.
Fill light only. Fill light should be located close to the lens axis, to fill the shadows the lens sees - did I mention that? :). Frontal light, to NOT add another set of shadows. So to be frontal, it must be back with camera, to allow camera to see around it. We can see this fill here is not quite centered over the lens. A very frontal light will not make any shadows on the face, but we have some here. The near side is well illuminated, but the far side is in shadow (in some degree). This fill is not quite lighting same as what the lens sees, not quite pure flat frontal fill, so it could be better to center the fill behind and above the camera. If you have the room and the flash power, why not try behind camera? But really - this time is mighty close, and it is the opposite side from main light - the main will also be "fill" in this case. It works out OK, but still, fill as close to lens axis as possible.
Fill light is metered here (at the subject) to set it to f/5.6 (exposed at f/10), which is one stop less than the Main light at f/8 - a one stop ratio of the two lights. With an incident meter, both main and fill are metered individually at the subject, basically from subject's face, in a consistent way every time. You can do this setup on yourself, before the subject arrives (a remote shutter button is handy). You simply meter the lights to set their power level to give the results you want to have ... and to give the ratio you want to use.
For beginners to flash metering, the incident meter measures the instantaneous flash actually at the subject's position, and reports brightness as an aperture value needed to match its exposure at that distance. Metering at f/8 is a brighter light, and metering at f/5.6 measures a dimmer light half as strong, meaning that the camera aperture must be opened to f/5.6 to match the dimmer light. This would be correct for either Main or Fill light alone, but with two lights, the two together always "add" (brighter than the brightest one), so that the camera likely needs to be set to 1/3 stop (f/9) or 2/3 stop (f/10) brighter than the main light f/8 (depending on the ratio) - but simply just meter it with both lights on.
Normally the first rule is to always put the large lights "as close as possible" to be as soft as possible. The main light is close, but the fill light is far back. How can it be soft? Well, it surely does cast a shadow we wouldn't like. However, we have placed it as close to the lens axis as possible, both are on the same angle, so the lens cannot see any shadow cast by it (any shadow is directly behind the subject, out of sight). The lens sees a very flat frontal fill. However, if the fill light is not on axis, it certainly ought to be very close too. Side lighting causes shadows which show detail, but which emphasize skin imperfections. Flat frontal light fills everything evenly... anything the lens can see, which reduces the shadows that delineate detail (less shadows in the wrinkles). So we are compromising, a nice interesting soft side light, and flat frontal fill to tone it down in degree. Ratio is the degree of that compromise.
Reflectors: Using a reflector instead (for fill - an inexpensive white foam board is very good) would be another way to add light to fill that dark side. It is not frontal, but it can work very well to help the dark shadows. Closer is brighter, and a reflector naturally works more efficiently from the side opposite the light, but fill is better from the front. It can still work great, but maybe compromise more toward the front all you can. Other than perhaps size, the difference between a reflector and a second flash is that the flash will be more versatile, since flash can be placed anywhere you want it, and power level can be set to about any intensity you want. Where you want the fill is very near lens axis (frontal), and the power level lower to create the ratio you want.
But single light portraits are standard lesson assignments when starting to learn lighting, and will be very good experience for everyone. Maybe not the easiest way, but results can be stunning, and it causes us to think about the basics. Perhaps a reflector could free up your second light for the background or hair. That is another story, but some Reflector Ideas.
Background light only. The background was black in the main and fill pictures above (8 feet back), so this light (placed behind and hidden by the subject) illuminates the background, and the subject is in silhouette.
This pattern only confuses TTL metering, which will want to illuminate the center subject. Which might be compensated drastically, but you simply need a manual light here. Notice that the background light and the hair light do not influence the exposure. So to be sure they don't, do meter the exposure (Main and Fill lights together) with these two lights turned off (power switch off). This is same f/10.
The background is the subject of this one light, so you meter at the background surface (all the other lights are metered at the human subject surface). Generally, this is one light behind the subject, hidden by their body, aimed back at background. A flat background only needs a bare reflector (or maybe a grid or snoot to make a narrow pattern). No point of an umbrella or softbox on a flat background with no detail, there are no shadows to soften. A bare speedlight works well (except for waiting on recycle time).
A colored background is usually set to be about same level as the main light (might be set to meter the same f/8) - which is a good starting point, but more or less light can change the same background drastically.
White backgrounds must be brighter, lighted to be a half stop to one stop more than main (Speaking of incident metering. Reflected might be three stops). I favor less instead of more, but enough to burn it out (and hide all the wrinkles), and clips them to be clinical WHITE 255, evenly everywhere. But don't let a strong glare from a strongly lighted background reach the subject. Background distance is your friend in many ways, but an unlighted white background probably comes out gray (because it is more distant from the other lights).
Black backgrounds - to appear black, you try to keep the light off of them. No background light. You place the subject more forward, with the background farther back, to keep it in the dark. Moving the subject closer to the lights, means you turn the lights down, which means less reaches the background. Or both, a distant background and a near subject. Any black cloth or paper will reflect light and be visible as such. If you want it invisibly black, you have to keep the light off of it. Black velvet is the exception - virtually no reflection. If photographing jewelry laying directly on jet black cloth, you definitely need a yard of good dress-quality black velvet.
Hair light only. TTL cannot meter this patch of light - it needs to be a manual light. It varies anyway, dark hair needs maybe a stop more than main light, light hair needs maybe a stop less than main light. Don't overdo it. An incident meter can meter it (at the hair itself) to know what you have and where to start (or how to repeat it), but it is trial and error with different hair, so you have to look at its result (a test picture). The other three lights can simply be metered, to be how you know they ought to be.
(Nebulous description) The Hair light is sort of 45 degrees high and maybe 45 degrees to one side. Back toward the top of one background stand is usually a good place.
Hair light power needs human verification. A rule of thumb is that dark or black hair needs about +1 EV than the main light. Light or blond hair needs about -1 EV less than the main light. This means that a new subject needs checking again. Take the picture and check it.
Some say the hair light should be on same side as main, and about as many say on the opposite side from main (which I perceive as sort of a side fill, lighting side of long hair maybe down to neck, more than a top spot). Others put it directly above (a top spot). I use same side, it seems more natural, to try for a small accent. Too much is Not a natural look. Start "looking" at every picture you see, magazines, TV ads, etc, and notice what the careful setups do, and what you like.
There is an 20 degree grid on this hair light, to keep its beam narrow. Computes less than two feet wide at five feet. A studio modeling light sure helps to aim it. For a speedlight, wrap a letter size sheet of paper (or a 9x12 inch fun-foamy will be more durable) around the head, long way around, with tape or rubber band, to make a nozzle on it. We can debate a white or black paper, but it really doesn't matter which. Just a simple straight nozzle will work fine, maybe 6 inches beyond the flash head. Then zoom the speedlight long. Without modeling lights, this nozzle helps to check your aim too - by sighting back up from just over the subjects head, to see if the speedlight lens is centered in the nozzle there.
Hair light adds sparkle, which always helps, if not overdone. Highlights and subtle tonal gradients to add interest. Certainly it helps separate dark hair from a dark background too. After posing positions, the hair light is the hardest part for me, probably because it is arbitrary, but it clearly helps. Watch that it does not highlight the ears or shoulders or cheeks or nose (aim higher to skim over the top of head in those cases, from the rear, instead of directly above).
All lights on, f/10.
f/10 because fill light adds a little, sum is brighter than the brightest. From f/8 main, fill with 1.5 stop ratio probably adds 1/3 stop to f/9. A 1.0 stop ratio probably adds 2/3 stop to f/10. Equal lights at f/8 each add to f/11 (two equal lights are double light, one stop maximum). Just meter the sum (both main and fill on, for the camera aperture setting).
If you prefer it to end up lower than f/10, then start lower than f/8 at your main (just keep the fill a stop or so even lower). The background would be set slightly lower too, both Main and Fill lights slightly increase it too.
With a one stop ratio on subject, there is still some intentional mild shadow left, to show contour (shading, considered interesting light), and to prevent face from being so abysmally flat. Idea is to look natural. You may prefer less fill and darker shadow for more contrast (for us rugged men typically). Or more fill to be more flat and gently even overall - the softest shots of women and children. Very flat frontal fill is better for hiding skin wrinkles too - shadows will detail and emphasize surface differences, but filling them does not show them so well (and maybe we should not zoom in so close either).
I went through a first phase where I imagined flat even lighting was better, until I finally realized a bit of ratio was in fact day and night better. The skill that we learn is called "seeing", to be able to recognize the significance of what we look at. Seeing is the skill of noticing and actually being aware of details that we look at, and that we try to create. I am very aware of how much more I have learned to see now, that I never noticed before (seeing is to actually realize what we look at, and to look for the details). No doubt there is still more I don't see yet. But saying, we must learn to actually "see" these mild tonal gradients, otherwise we don't know what we are creating (or how to do it again next time). It is all in plain view, but learning to see requires working at it to notice. The pictures in books on lighting will gain surprising significance After we learn to look with the goal of actually seeing.
Yes, there are two catch lights here, which is usually no big deal to me if both are high on the eye. Which is certainly not unique to this setup - there are two lights after all. One catch light could be spotted out if desired, with the Clone Tool, it's easy. But no one looks this close, and it is a very nice sparkle, almost a twinkle. Purists may argue for only one catchlight, but sparkle is what we want. We should start
looking at seeing all the pictures we see. One catchlight is common in old movie closeups, but pay attention to the TV news anchor's eyes in the studio, which is careful intentional lighting by professionals. You may have never noticed before (it's part of "seeing”), but multiples are certainly Not in disfavor. And not bad either, there is much sparkle and vitality, which is good, which is the entire idea, and catch lights are one of the most important things.
The Adobe Healing Brush is a big time tool that you should know (in Elements and Photoshop). Just drag it over skin imperfections, lines under eyes, and wrinkles and spots. They simply disappear, and the ladies always like that. The Clone Tool works well too, but the Healing tool blends automatically. Both tools have their uses.