Soft light is created by a relatively large and close light source, like an umbrella or softbox. It is soft because it is large and close. Implementation is easy, just open an umbrella, and place it close. This example uses only one light (no fill light), but to show the difference, first a hard light (a small light):
On-camera frontal light is very even (to a fault). It comes from the same angle that the lens sees, so there are no shadows on the subject. This is flat light, and featureless, uninteresting. Therefore off-camera lights are desirably used to cause intentional shadows and shading which is seen by the lens angle, to show depth and shape on the subject. But using a little control to soften harsh light is also a good thing.
The top picture is direct flash, and is a small light, but it is off-camera, so that its shadows will still show shape of the subject. Hard light (from the small direct flash, about where the top of the umbrella would be, same angle) causes dark sharp shadows, which is more contrasty. Certainly it is not flat lighting. And not real dark here, because the white background (curved up just a few inches away) is a reflector providing some fill (shadow is darker at front than at rear). Hard side light emphasizes details of texture, for example, the egg texture where the light is at 90 degrees to the surface... or for example, similar low side direct lighting is great to photograph the detail in a coin, it makes dark surface shadows to show the contours. But showing all surface detail is not always a plus (in skin complexions or wrinkles for example), and soft light has no dark shadows to emphasize surface texture.
The second picture is large soft light, the same speedlight, but now in a large close 45 inch umbrella at about the same place (4.5 feet, shaft is 30 inches long, top of stand is 24 inches from egg). Large and close is the idea (often "close as possible" is the idea for a reflected umbrella. A shoot-through umbrella can be much closer yet.) The large wide light still has a direction casting shadows, but wrapping around the subject more, because its large size is throwing light from many directions to the subject, coming from the left of it, and from the right of it, and from all sides of it. All these many light paths fill the shadows caused by all the other light paths. This self filling of shadows makes the shadows dim and indistinct and soft, being more just gradient tonal shading than actual shadows (the opposite of dark and sharp-edged and harsh). But "soft lighting" is really speaking of the shadow ON the subjects surface (we try to prevent shadows behind the subject, by greater background separation for example). This automatic fill and wrap greatly minimizes the shadows, but the remaining tonal gradient shading is still quite important to show the shape of the nose and cheeks and chin. The soft light is more smooth and even, vague dim shadows, and like magic, the width of the close light tends to wrap around the object(s) instead of causing a sharp terminator edge (like on the moon).
These examples added no second light for fill. If we did add a similar light from another angle, a second hard light will simply show two sharp sets of shadows, neither as dark, but distracting, not good. The proper concept of a "fill light" is a frontal light, from very near the camera lens, specifically to light the same shadows that the lens sees, without making more. A second soft light can simply make those shadows vanish. Except that we add the fill at a reduced level (with the fill "ratio" a stop or two down), to leave some of the gradient toning, so that the light will not be "flat", so we will have pleasing tonal gradients to show shapes. But no distinct added shadows as such (examples of that fill, Frontal Fill Here, and less pleasing Side by Side Here).
The soft gradient tonal shading is intentional and very desirable, it shows the shape of the object (it is not flat light, it is just soft light). The top pictures light's harsh dark shadows show shape too (and fill light can help its appearance), so off-camera light is better than on-camera. To prevent being flat, we need the gradient shading caused by shadows from off-camera lights (fill at a reduced level), and soft is smoother than harsh. All you have to do to get the soft light is to open the umbrella, and set it near.
What is soft light? It is large (wide) light that diffuses the shadows, converting them to subtle gradient tones that wrap around the subject. We like that.
How does it do this? It does it by the light being LARGE and CLOSE (which is really the only way to create "soft"). Diffusing a tiny or distant light is still a tiny or distant light. Is for example, a ten inch light large? Not really. It is larger than two inches, but smaller than 40 inches. However, if located only ten inches from the subject (macro work for example), then it can look and be large (paths coming from many angles).
How does Large and Close do this? Close makes Large appear even larger. Example: Say it is a four foot light (like a softbox or umbrella) that is four feet from subject (at a distance about equal to its own size). The subject sees it big and in-their-face, it being around 53 degrees wide as seen by the subject. This means some light is coming to the subject from 26 degrees on the subjects right, and some light from 26 degrees on their left (and top and bottom too, and everywhere in between)... because the light is that large and close. There are many paths of light to the subject, from all areas of this large light. There still is a predominate direction of the light, but all these light paths from the Large source fill the shadows made by all the other paths... resulting very vague soft diffused shadows, actually more just tonal gradients now than shadows, but these soft tonal gradients show the shape of the curves of the subject (interesting appealing light). Lighting is all about the smooth tonal gradients (which we call soft, obviously softer than harsh hard dark shadows). Learning to look and see this is the difficult part at first, but seeing is what lighting is about, and it is always there to be seen. Beginners just have to learn to see when they look.
Examples of light size, which causes this softening; wraparound and fill: (light size as seen by the subject)
All this assumes the light is off-camera, from an angle, normally maybe 45 degrees wide and high. This angle roughly mimics the sun's position, which we find natural. It intentionally makes shadows which the lens can see from its angle, to add interest and depth. This is the full opposite of flat. However, large and soft makes those shadows very diffuse, gradient tonal shading, wrapped-around, pleasing instead of dark and harsh. We like that.
Learning to see this gradient tonal shading is what lighting is about. It involves thinking about it, and learning requires we work at it some before it becomes obvious and automatic (seeing is a skill). For awhile, beginners may think they look at their lighting, but they do not see, and don't know what they do not see, until they realize what they are looking for (this is classic, we all started there). It is all there to see, and when you learn to look (and think) and see what you are creating, then you know what to do about it.
A large close light source creates soft light, by virtue of appearing large to the subject. Conversely, diffusion domes and bounce cards are tiny devices, too small to be "soft". All they can do is to provide some direct frontal fill when the flash is bounced from the ceiling. The ceiling reflection is large, but both devices are small, direct frontal fill. There is no magic, but it helps to understand what these actually do. The evidence is in the pictures below.
Note one big factor here.... The pictures on this page below are all with the flash off-camera, NOT on the hot shoe (next page is on the hot shoe). One disadvantage of the hot shoe flash is that it is a flat frontal light, very even on the subject, with shadows hidden directly behind subject, but often not the best place for the light. With the light off-camera (at an intentional angle), it creates visible shadows (that the lens can see), for example the shading gradient across the egg above. This shadow shading "shows" the shape of the object, and looks natural, looks good. Whereas a direct flash would just show a flat white oval. However, the off-camera flash can cause severe shadows "behind" the subject. One advantage of the hot shoe direct flash is that the flash position directly above the lens puts most shadows directly behind and below the subject, mostly hidden there, out of sight of the lens. The lights on this page are all off-camera, specifically to show shadows. Next page is about on the hot shoe.
This shell is an irregular shape object, with possibilities for shadows. It is turned here to ensure some shadows. An on-camera flash would be frontal light (illumination from same angle that the lens sees), which would create no shadows on the subject for contrast - so that would be very flat and dull lighting. The flash is off-camera here, wide to camera left, to intentionally create shadows on the subject for the lens to see - but softened to make gradient tones on it, to show its shape. Lighting is about the SHADOWS ON THE SUBJECT. The situation here and now is to look at some possibilities, for ideas about what the lighting can do - and the differences in the ways we do it. This is tabletop work, with a sheet of red craft paper background. Of course, it could just as well have been a human face in a portrait. The shell is about 8 inches long. Most of these use one SB-800 speedlight, off-camera (at the end is two in umbrellas). All of these are ISO 200 and f/8. I used 1/200 second shutter speed to keep out the ambient.
1. SB-800 speedlight flash in one white 45 inch reflected umbrella, zoom 24 mm zoom at full shaft length to fill it, fabric apex 3.5 feet from the shell.
This is a soft light. Vague dim shadows with indistinct soft edges, very nearly shadowless - or rather, the shadows become mild tonal gradients. We need the tonal gradients to show the shape of the subject. The umbrella is relatively a very large "wall of light", seen coming from all directions to the shell, at least from the left and from the right and from above, which simply wraps around the subject to fill its own shadows, to create "soft"
The idea is Large and Close. Farther away would create darker and more distinct shadows, because the umbrella appears smaller there, with less filling effect. A distance near the umbrella diameter will create very nice softness. Twice that far seriously reduces the effect, but still better than nothing. Distant scenes like groups don't need the same full degree of softness as do close up portraits, but a tiny light does not even try.
The standard goal for most portraits is for reflected umbrellas to be "close as possible", to be "large as possible", to be "soft as possible". Up until the distance is about the same as the light source diameter, which is sufficient. Normally though, close enough to just barely keep the light stand out of the picture.
2. Same white umbrella, but in a shoot-through configuration, 24 mm zoom, fabric apex at 2 feet, closer.
Almost the same, but frankly, I always think the reflected umbrella is softer, simply because the shoot-though suffers from its curved-back edges, so the light from halfway out to the edge is not even hitting the subject. The light hitting a near subject comes from only a smaller area in the flat center of the umbrella. Even at only 2 feet, not as much wrap-around, and the contrast is higher. The reflected umbrella is nearly twice as far here, but it still does more - it can use its full width to be larger. I choose the reflected umbrella any time it is possible (if I have 3 or 4 feet of room to accommodate its light stand). But if you need it to be real close ... shoot-through can do that.
The background on right side is a little darker, which is inverse square law falloff due to the closer umbrella at 2 feet. This shell is 8 inches long overall, so the field of view is around one foot. Too close can have depth issues.
A shoot-through umbrella necessarily removes the black cover on the umbrella. Then, still only about 1/3 of the light goes through the white nylon, and 2/3 is reflected out the back of a shoot-through, spill into the room. A reflected umbrella can simply add the black cover to prevent that 1/3 spill into the room. The black cover has no other purpose except to absorb that spill.
3. Direct flash, at 4 feet from shell (exactly the same flash position, the shoot-through umbrella was simply removed).
This is NOT a soft light. Sharp-edged distinct dark shadows. Instead of a 45 inch umbrella, this light is a tiny two inch flash head. No large light, no light coming from left or right or all around, no self-filling of shadows. A direct flash is often fine, sometimes ideal, but it is just not soft. Contrasty shadows are good for showing surface detail, whereas soft smooths things over and minimizes blemishes. There are times and places for each method of course. Closeup portraits of human faces like it softer.
You are looking at the shadows on the subject, right? Lighting is about learning to see what is happening.
Don't just notice the background shadows on the red paper. Important of course, and characteristic, but normally we can eliminate those (with greater background distance, and/or larger softer lights, like the first or last umbrella pictures here). Instead, here, notice the shadows ON THE SUBJECT. Lighting is about the shadows on the subject, which if soft, are mild tonal gradients which show the shape of the subject.
Here is an animated GIF comparison of these first three images.
4. Small 8x6 inch speedlight softbox (this was Fotodiox brand). Same four feet from the shell, 24 mm zoom. Just for fun, just to show it is too small to make much difference. The shadows are slightly lighter (but this is real close, only four feet - there will be less effect if farther). It should be better for macro work, at a distance comparable to its size. Maybe arguably better than nothing, the shadows ON the shell are slightly lighter, but there is really hardly any difference at any normal distance... wishful thinking.
5. Same small 8x6 inch speedlight softbox - Same four feet from shell, but with pull out 17 mm wide angle diffuser down inside it, to try to illuminate the inner reflective sides of the softbox - because studio flash is bare bulb inside softboxes. The speedlight lens is really better suited for umbrellas. There is nothing wrong with umbrellas.
Just playing here, and I can't say it helped. Compared to the other methods, anything tiny is still very much like unmodified direct flash. Even at only four feet, it is just too small. At least in any fixed situation, there are much better choices.
6. Nikon SB-800 diffusion dome, and direct flash. The dome is not intended to be used this direct way. The effect is not totally zero, it does seem slightly better than the miniature softbox. The direct shadow is sharp and as dark, but the fill is better on the subject (room wall reflections? There is a beige wall 6 feet to the right, and the ceiling 7 feet above... which distance is like four stops?) But it is still minimal, still wishful thinking, just too small to have effect. Again, this is only at four feet. Greater distance would make the size even smaller, with even less effect. If walk-around portability is not an issue, we have much better solutions.
Everything that happens is there to see in the pictures. If we cannot see what we imagine is happening, then it did not occur.
Here is an animated GIF comparison of images 3, 4, 5, 6.
All are tiny, none have any appreciable effect on the direct flash, even at only four feet. Macro distances (inches, distance comparable to light size) should see more effect.
7. Bounce flash (only, no extra attachments). Still four feet from shell, but with flash head simply aimed up. Ten foot ceiling, seven feet above the table, five feet above the flash. Light and shadows are from above now, and the ceiling light is very large and soft.
Bounce flash always seems worth a Wow, and it is so easy to do, just point the flash head up at a normal ceiling. A wall can work too. If not white, it can add a serious color cast which you will have to correct (but we always have to deal with White Balance corrections).
And we have extras we can add (next), which are often confused.
8. Bounce flash, same but with SB-800 diffusion dome added. The dome provides forward spill, for fill, usually excessive. You did see the direct shadow? Maybe not as dark as direct flash (the bounce fills them). Notice the direct flash has obliterated the bounce shadows (too strong, not a good thing). The bounce does still help to lighten the direct dome shadows. If we stepped away farther back to make the direct spill be weaker, the bounce distance becomes greater too, so the flash power is cranked up, and we didn't gain much. I think this one is better without the dome. Compare the detail along the lower third, and back towards the "tail". Direct spill flattens the gradient tones we need.
Dome marketing leads us to imagine the dome bounces light on all the room walls and comes back from different directions, but the Inverse Square Law about wall distance says this may be unlikely. Unless the room is pretty small, it would be weak compared to the direct forward spill. A larger dome, 4 or 5 inches in size and selling for $50, won't change much (still tiny).
These dome or bounce card devices have no magic properties. They just spill some frontal fill. Which of course can be helpful, but diffusion of a tiny light just scatters the light outward, meaning much of it misses the subject now. We need a large source to scatter it inwards toward the subject, from different angles. The property that can have effect on the subject is direction, due to the size of the light source, as described before. The ceiling is large, and the ceiling bounce does most of the work. The dome or bounce card simply aims some direct forward spill for fill - which a little is a good thing, but we should not believe in magic photons. You should literally "See" the results of your beliefs, else they did not happen.
9. Bounce flash, with a bounce card, but pulled only 1/2 way out (3/4 inch tall, which is a smaller card, less frontal fill). The card provides forward spill for fill. Here, we still see the bounce shadows from above (the stronger dome spill obliterated them). We don't notice the card shadows, weak compared to the major bounce lighting. Sometimes less is more.
If your flash does not have a pullout bounce card, a white 2x3 inch card or paper (business card), or white fun foamie (basic craft store supplies) and a rubber band generally works great as a bounce card, and can be the same size as the built-in pull-out card. The "working" or effective area (above the flash head) of this Nikon card is about 1.75 x 1.5 inches WxH. Just don't overdo the size. A larger card will cause a darker direct shadow, and wipe out more of the bounce. A large card (trying to mimic umbrella size) is only used when bounce is not a factor, maybe outdoors. Indoors, sometimes less is more. We don't want the fill light to obliterate the bounce, and to substitute its own direct shadow.
The black bands shown on flashes above were kids bracelets, 3 for $1 at Walmart once. They are something like hard rubber, the right size and stretchy enough to hold a bounce card of any size. I bought this black professional model, which says Rock or Punk on them.
10. Bounce flash with bounce card pulled fully out (1.5 inches tall). Slight direct shadows now (to judge our fill level), but we still see bounce shadows, and perhaps they are even still dominate (darker than the direct shadows). Remember, the bounce and the flash is not on-camera here. We can judge each lights level by these shadows. Look for them, to know what you are doing, and how well you are doing it. At this close distance, halfway out above maybe seems better, less added, but less damage done (see the gradient tonal shadows "on the subject").
The forward spill from dome or bounce card adds catchlights in the human subjects eyes, very important for people portraits. The catchlight adds sparkle, vitality, a sense of someone being alive in there. Hollywood villains don't often get catchlights. Catchlights are definitely one of the most important purposes of the frontal fill (and catchlights do not require much bounce card). Another purpose is to lighten any dark shadows. Just never add too much of it, which becomes direct flash then.
The huge do-it-yourself bounce cards are laughable size, at least for bounce. Maybe reasonable if outside, with no bounce opportunity. With the large cards, there really is no point of wasting flash power on the ceiling (most lean over the top of the flash so they don't). When using hot shoe bounce flash, I usually use this little card, even at group distances, believing its lesser spill helps better (hurts the bounce less) than the dome. Again, a major purpose of either is to add catchlights in the eyes.
Here is an animated GIF comparison of images 7, 8, 9, 10 (Bounce).
11. Direct flash again, from four feet, with a large white reflector close on the other side of the subject for fill. This was a 42 inch collapsible nylon panel (larger than useful here). An inexpensive white foam board from the craft store works just as well, maybe better. It is still a tiny direct flash, and you may have to look back at the direct flash (3) to realize it, but the very dark shadows on right (on shell) are now lighter. It is a very easy improvement. A letter sized white paper would have helped here. A fill reflector is normally a big help for single light lighting.
You are looking at the shadows on the subject, right? Lighting is about learning to see what is happening.
12. Same nylon reflector used as a shoot-through diffusion screen at about two feet (about half way between four foot flash and the subject, so flash can fill its size to make it be large). This about the same as a shoot-through umbrella, except it has potential to be larger. The flash has to be a little way back, to illuminate its larger size.
The reflector lightens the shadows by modest back fill. The diffuser (being large) fills them by wrapping around from all angles, including from the wide edges. Using two as both reflector and diffuser comes to mind, which is still using just one light.
Here is an animated GIF comparison of images 3-11-12 (Direct, with modifiers).
The Hot Shoe Extension Cord only allows about four feet before its coil tension tries to tip the light stand over, but that still allows many things. This is an old version Nikon SC-17 cord (plentiful on Ebay, less expensive than the current SC-28 cord). Only difference is the new style rotating lever hot shoe lock - but the flash pin is spring loaded, we can still simply lower the pin on the SC-17, and it isn't going anywhere. I've used it for years.
Do NOT use TTL BL mode flash with the extension cord off-camera. D-lens distance of focus is not same as the flash distance then, which will screw up the exposure calculations. Even if the flash is in an umbrella, if the head is not tilted, the system assumes direct flash (and checks D-lens status). If necessary (for example SB-700, SB-400), use Spot Metering mode to override it to be TTL mode. Which is NOT Spot metering for flash, but it forces TTL mode, which ignores D-lens distance data. Don't forget to reset Spot metering Off when done, it greatly affects metering ambient light.
13. Two reflected white umbrellas (two SB-800 using Commander), close to subject, but simply arranged left and right of camera, both equal. Soft, but equal lights are pretty flat (no shadow tones for contrast). Two direct lights will make two sets of shadows (seen extreme left and right here), but one umbrella pretty much fills the others shadows, so it is flat and shadowless.
This could be proper and desirable lighting to evenly light a wide scene, or evenly light multiple things like a group. Or for something like copying paper documents, which are flat (meaning smooth), which are without opportunity for shadows or gradients. But it's pretty flat lighting (meaning dull, even, low contrast) for most localized things (with one obvious subject).
14. Two reflected white umbrellas, close to subject, simply arranged left and right of camera, same as above, except right one is compensated to be -2 EV (does not fill shadows from left light as fully). Adjusting one light to a lower fill level is always better, less flat, more contrast, more interesting gradient tones. The end shadows on left are gone, shadows on right are darker (and more interesting lighting). A wide scene or group needs even lighting, but any one localized thing needs a lighting ratio.
15. Two reflected white umbrellas, arranged as Main and Fill now. Meaning, the Main is still close, and still about 45 degrees high and wide (to make shadows), but the Fill is near the lens axis. The job of Fill is specifically to flatly light exactly what the lens sees, to fill the shadows the lens sees, without adding its own shadows. The fill light could be in front of camera, just to one side, still near the lens axis, light stand pole very near the lens barrel for example, with umbrella slightly above camera. Behind the camera just allows centering it completely, but close is normally close enough. Fill could have been placed higher above the camera, but I held one hand over the camera eyepiece (to block the flash) so that preflash light into the eyepiece would not affect TTL preflash metering (the meter is in the viewfinder, and the eyepiece is another entrance).
Not a lot of difference this time, it wasn't a big move, but having the fill light near the lens axis is an honored tradition. Specifically, to fill the same shadows that the lens sees, without creating a second set of shadows, but only filling the first set. "Fill" does not mean the shadows disappear, does not mean 100%. The -2EV level means 25%, and they only become lighter, to become smooth gradient tones which show shapes. The lighting is too flat without these gradient tones.
Here is an animated GIF comparison of images 13-14-15 (Two umbrellas).
One point is that we have to learn to "see" these shadows we are making. We can associate those shadows with each light we are using, to know what we are doing. We can think about the shadows we see, and decide if that is the way we want to see it. If we use some special procedure or gadget, we ought to be able to see the actual result of that procedure, to know if it actually does anything or not. Wishful thinking does not always get it done. :)
Make no mistake, the tiny domes and bounce cards do NOT add diffusion. They are far too small to be able to that. Size adds diffusion, and these are only 2 inches in size, and there are no miracles. What they do is to add direct forward fill for bounce (and of course the catch light sparkle in the eyes). You can see that direct shadow, simply just look at the results. For a hot shoe mounted flash directly above the lens, this direct shadow is behind and below the subject, not often observable. The tiny devices are simply too small to be "soft". The ceiling bounce is large and soft, and is aided by the frontal fill. If overdone, the fill is just a flat direct flash picture, but slight fill for bounce is the goal, and is the way the results should be evaluated.
Do try this at home, to satisfy yourself. The results are easy to judge when you know what effect you are looking for. Everything that counts is all there in our pictures for us to judge, the hard part is that we first have to learn to see it. The idea is to think about what you see actually happening, to understand that the dome or bounce card simply adds direct frontal fill to aid bounce (and adds the catchlight in the eyes). This concept should be conscious in your mind at the time.
The next page shows a second similar photo series, with frontal lighting from the camera hot shoe, which is more how the bounce card or diffusion dome would be used.