Strobe to umbrella distance
Light subject and dark building
White clothing changes flash results
Change the distance and you change the light
Portable flash in the gym
Camera to subject distance and flash meters
Small main and big fill
Controlling specular highlights
Loss of detail in dark clothing

Strobe to umbrella distance

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Hello. I just received a used studio flash and silver umbrella. Does it matter how close the flash is to the umbrella? Thank you.
Francis:

Dear Francis:
The distance from the flash unit to the umbrella controls the apparent size of the light source as seen from the subjects perspective. It’s really not too difficult at all. Just think about what is happening. With the strobe very close to the umbrella, the light will be very intense on the umbrella right in front of the strobe head. Because the light falls off as the distance from the strobe head to the umbrella increases, your umbrella will be progressively darker toward the outside edge simply because your strobe is a greater distance from the outer edge than it to the center. When you pull your strobe out from the umbrella, the distance from the strobe to all parts of the umbrella is about the same. This will provide a much larger apparent light source size for your subject.
A smaller light source will produce a smaller and more defined transition between the highlight part of your subjects face and the shadow area. This area between the shadow and the highlight is called the shadow edge. A smaller light source will produce a somewhat harder look to your subject. Character lines will be more defined. Use this when you wish to add character to your subject. An older man with a beard is a good example.
When you use a larger light source, your shadow edge will be wider and more gradual. Character lines will be less defined and a softer look will be observed. A larger light source is more flattering to an older lady with many character lines than a harsher, smaller light source. These effects are also controlled by how close your light source is to your subject. When your light is in closer, your subject see an apparent size that is larger than if it were positioned at a greater distance. A combination of light source size and distance from light source to subject will allow you a high degree of control in the quality of light that falls upon your subjects face.

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Light subject and dark building

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I took a picture of a person in a front of a building at night using a flash , Portra 400VC, and a 30mm 5.6 lens. On the picture I see the lighted person in front of a very dark building. Does anybody knows how to do this right?
Victor

Dear Victor:
First let's look at what you said in your question. You indicated that you took a picture in front of a building using flash at night. The film is not that important. What you didn't say was the distance from the flash to the subject and also the distance from the flash to the building.
There are not one but two things that contribute to the building looking dark. First, it's dark because the ambient light that is on it is far lower in intensity than the strobe light that is striking your subject. You can indeed help this situation along by dragging your shutter which will allow more of the available light from the neighborhood to build up on the film after your strobe fires. Be careful about long shutter drags. If you go too long, you can get color shifts on your main subject since they are in the ambient light as well as the building. The tungsten, neon, and fluorescent light that might be in the neighborhood will build up on the subject as well as on the building. You must find a balance. Also you might wish to work on a tripod so you will have a more stable situation.You can also get halos around your subject as they move slightly during the long exposure. This is rarely desirable and suggests a shorter shutter drag but still long enough to let the building "build" a little.
The other reason the building is dark is probably because the distance from the strobe to the subject is far less than the distance from the strobe to the building. If your subject is standing with their back up against the building, then the building will receive about as much light from your strobe as the subject did. In this situation the building will be lit just fine. If your subject is 8 feet from your camera/strobe but is standing fourteen feet out from the building, the building will receive three stops less light from your strobe than the subject did. This will definitely keep the building looking pretty dark. Remember that the light falls off as the distance from the light source to the subject increases. If the building is farther from the light source, it will receive less light than the person. You can drag the shutter which will allow available light to build up behind the subject as one method of overcoming this problem. You can move your subject in closer to the building which will allow more of your light to reach the building but you will see less of the building as a result of being closer to it. A simple solution is to use a second light and light the building independently from your subject.

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Why am I having this problem? I shot a bride and groom during the ceremony. The bride, groom and minister were all dressed in white at the alter. Nearly all of my close up ceremony exposures came back looking underexposed on the proofs. Could it just be poor proofing? The Lab was telling me that my proofs were -.05 to -1 under exposed. What did I do wrong? This is embarrassing because I have to give this to my client.
Mr. Time

Dear Mr. Time:
I believe that your problem is a combination of two different things. Number one is possibly the printing. I would have to see the negatives to know if it was a big contributor but it is a possibility. What I suspect the main problem is, is the 18 percent gray syndrome that usually happens when your subjects are all dressed in white and your flash is being used in an automatic mode. If you think like your flash you can figure out the problem pretty easy. What is your flash programmed to do? It is designed to see the light that it puts out as it is reflected off of the subject, evaluate it and shut down in time to generate a negative with an 18 percent gray subject. This will in most cases produce a negative that is printable.
Now, what does your flash say when it sees a bunch of people all dress in white? It says, “gee, look at all that white---I need to shut down early so it will be 18 percent gray”, and so it does. The result is a negative that is quite underexposed. Not from any fault of the flash but because of the very nature of how flash units are made, which is for the typical, average scene. They think just like a flash meter. They want to make every scene look like a gray card.
The reverse of this problem is just a common but not complained about as much. When you have a bunch of black suits and they are not too close to a white wall, the flash will say, “not much light coming back, -better keep pumping it out so we will get the subject up to the brightness of a gray card”. The result? Over exposed negatives. More light than you needed. Most photographers don’t notice a big problem with these at first because they are still printable even though they look quite harsh from the contrast build up which occurs with an over exposed negative. An underexposed negative on the other hand prints as a flat, low contrast image. Muddy and without detail in the dark areas.
Enter the photographer and his or her experience to offset the mechanical devices that only know how to think like a gray card. Now that you know what the rules are concerning flash units, you can compensate next time when this scenario happens again. You can open up a stop or so when everything is white, which will help generate a proper negative. You can close down a bit when everything is very dark. Don’t forget to observe your background and how close you are to it and what color it is. It will contribute to what the flash unit sees and thinks about. Over time, you will become quite familiar with the characteristics of your flash and how it thinks. You can then compensate whenever special situations pop up. There is nothing like experience.

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Does light from a softbox become harsher as you increase the distance away from subject e.g lighting a face in a studio situation?
Thanks,
Vince

Dear Vince:
When you move your main light source away from the subject, a number of things take place. Here they are:

1. You reduce the amount of light falling upon the subject from the main light. While the light source itself never changes in size or output, the increased distance causes the light radiating area to look smaller from the position of the subject and therefore will have less effect.
2. You make the background look lighter. Yes that is correct. Lighter. As you reduce the light on the subject, you reduce the light on the background as well but to a lesser degree because of the greater distance. The change is greater on the subject than on the background which is farther away from the main light. When the exposure is adjusted for the new lesser amount of light on the subject, the lens will be opened up. Since the amount of change to the background was less than that of the subject, the background will now appear lighter than before even though, the light was moved away.
3. You decrease the width of the shadow edge on your subject because of the apparently smaller light source thereby making shadows more defined.
4. You would actually reduce the ratio between the main and the fill (assuming you didn't disturb the fill light) which will make the now more defined shadows, less dark.
5. You increase the specular density relative to the diffused highlight or true tonality of the subject. In simpler terms, your portrait subject will look more oily as the highlights in the skin will be brighter relative to the natural color of the skin. Moving the light source in closer will reduce the specular density. Specular by definition means "mirror like". The tiny oil beads on the skin each reflect the light like a tiny mirror. As the light source is moved away, the highlights in each bead of oil reduce in size but remain at the same brightness. The fact that the light on the subject has reduced because of the increased distance makes it necessary to open up the aperture of the lens to get a correctly exposed piece of film. As a result of opening up, the specular highlights (that never really changed in brightness) are now overexposed and appear much brighter relative to the diffused highlight.

So the bottom line is that every move you make with your light has a specific effect that is predictable and quite specific.

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Hi Scott,
I have been reading you web page, lots of good info for someone like me thinking about creating a studio. I read your recommendations on flash meters which brings up a question that has been bugging me. I have not used a flash meter yet, perhaps when I do it will answer itself. But, assuming the flash meter gives you an f stop reading for a given flash level, do you have to compensate for distance from subject to camera, and focal length of the lens? Seems to me the flash meter knows how much light reaches the subject, but has no idea about how much light will actually reach the film.
Thanks,
Steve McCain
PS: I Love your diffusion panels!

Hi Steve:
I am glad you enjoy the web site. I like the way you think. In this case you are partly correct and it shows me that you are thinking. To answer your question, when you make an exposure, a flash meter is first pointed toward the light source and an incident (flash) reading is made to determine what aperture to use. We are measuring how much light is reaching the subject so we know what f-stop to set the lens at. Varying the distance from the light source to the subject changes how much light reaches the subject. However, changing the distance from camera to subject wouldn't change anything. Think about it. In moving the camera did we change the amount of light reaching the subject? Not at all. From the subjects point of view, things never change with regard to the brightness of the light source. Moving the light source in closer however, now produces a larger light source as seen by the subject but the brightness level of the light source itself is of course the same as it was. To illustrate this principle, let's pretend that we have a soft box positioned about 20 feet away from the camera pointing directly at it. Now let's pretend that we have a spot meter that will read a small spot on the surface of that soft box. We take our reading from the positon of the subject. Ok, we take a reading. Let's just say it says to set the aperture at f 8. Remember we are taking a spot meter reading of the light source itself. You would not normally do this. We are doing it here only to prove a point. Now we move the box in to about half the distance it was before and take another reading off the surface of the soft box. Is this reading the same or different? It is the same. Why? The brightness of the surface of the box never changed? It simply got bigger from the subject's point of view. So why is it that if it does not change in brightness that we will get a different reading when doing the normal incident reading from the subject postion toward the light source? Simple, the surface area of the light source is now bigger from the perspective of the subject. Brightness is the same but there is now more real estate with THAT brightness.
Knowing this we never need be concerned about a difference in exposure just because we moved the camera in or out. Think about the distance from light source to subject as your most important variable and you will do just fine. The lens used or the distance from the subject to the camera make no difference to your exposure. That gives you one less thing to worry about. Happy shooting!
Sincerely,
Scott
PS Thanks for the kind words about my panels. I always enjoy hearing from people who bought them from me and are enjoying them. It's great fun being in total control of the quality of light.

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I am experimenting with lighting techniques and I am leaning towards non-diffused main lighting to add a more dramatic effect to my pictures. I am thinking of using a diffused fill light to get the lighting ratio in an acceptable range. What do you think?


Hello Roger:
What you are talking about is using a small light source as your main light and a large one for your fill light. This is a perfectly fine combination for portraits where you wish to achieve the look of the old Hollywood portraits. Small light sources, deep shadows and lot's of makeup to keep specular reflection to a minimum. It is usually best to keep your fill light larger so as to not create shadows from it. The fill should be invisible with regard to it's location so ideally it would come from the position of the lens. Since that is not practical, placing your fill above the camera and as close as you can without it being in your way is the best choice. When the fill is away from the camera axis there is always a chance that you will see shadows created by the fill which will be in a different direction than those of the main light. Conflicting shadows are rarely desirable. With this in mind a large fill light near the camera axis is generally the best idea. The small light source is also fine for doing portraits but not all portraits should be made this way. Use a variety of light source sizes rather than just one for your main light. The only way to have this kind of control with a single light source is to use diffusion panels. Panels provide unlimited control of light source size without having to change out things like umbrellas and soft boxes which cannot be easily or quickly changed to another size.
Achieving the desired ratio is easy if you have the ability to control the amount of light coming from your light source. For your fill, you can simply feather (turn slightly away from the subject) your umbrella until the amount of fill light is correct. This is far more effective if you are using a highly reflective silve umbrella like the one I use and sell in my product area. For your main you can attach a set of barn doors which will allow you to again control the amount of light coming from the light source. When you have control of both the main and the fill, you should have no trouble achieving a wide variety of ratios and lighting styles by simple mechanical means. I always prefer a mechanical change rather than relying on an electronic control that may not provide linear change between the modeling light and the strobe tube. Knowing what you will get and getting what you see is ALWAYS good news.
To learn more about our diffusion panels, click here.

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I have been studying a lot of beauty images and the thing that I find most disturbing is the specular highlights. In some of the more amateur photos, the specular just destroys the photo, blowing out all color. Now, the more professional photos I don't see such an intense specular highlight. I see a more even skin tone, rendering so much more quality and beauty to the photo. My question is how do you control the specular qualities of a photo to get the more even skin tones?
Pete

Hello Peter:
The brightness of the specular highlight is technically referred to specular density. This refers to the density of the negative in that area. The specular density is controlled by the size and proximity of the light source as well as the surface efficiency of the subject.
A billiard ball has great surface efficiency so you can expect to see a good specular reflection of the light source in the ball. Now if you took a sand blasting rig and blasted that ball until the shine was gone from the surface you have reduced the surface efficiency and your specular highlight will now be diffused and not defined at all. This relates to skin because everyone has different amounts of oil on their skin. Some people have very dry skin (lower surface efficiency) and some have oily skin. (high surface efficiency) The application of powder will reduce the surface efficiency and thus the specular density. This is one method of control.
Second is the distance of the light source to the subject. Assuming that the light source itself remains constant, you could take a spot meter reading of the light source. You would get the same reading whether you were 1 foot from it or 20 feet from it. Remember it never changed. It just changed it’s distance. With this in mind, we must remember that a specular reflection is a mirror-like reflection of the light source so no matter how you change the distance from the light source to the subject, the specular density remains the same. What changes is the amount of light actually reaching the subject that we see as a diffused highlight. THAT reduces as the light moves further away. As a result, when we meter we will get a new reading that indicates a wider aperture to let in more light. Now we have a diffused highlight that is still correct but guess what happened to the specular light? It now becomes more intense because we opened up and that highlight is now recorded with greater density on the film even though it never actually changed. What we have now is a brighter specular highlight RELATIVE to the diffused highlight.
If you elect to use a large light source, closer to the subject you will reduce your specular highlights dramatically. Most of my head and shoulder portraits are done with my diffusion panel less than two feet from the face. This is particularly beneficial for subjects with oily or dark skin because their skin will now record on film looking much dryer and less oily.
Once these principles are understood, you will find it easy to be totally in control of all characteristics of your light.

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Scott,
I did a photo for a friend and his wife. She wore a black dress and he wore a black coat. I used an N90S in program mode with my camera set to -.3 to fill flash in open shade. The picture was great but the detail between the coat and dress was lost. They looked as one so to speak. What did I do wrong?
Take care,
Rick

HI Rick
First, these modern cameras with all of their computer controlled compensations for everything provide no information as to how they are doing it. You simply put it at some setting and are supposed to trust it. Why your picture looks the way it does will remain a mystery as long as you let your camera think for you. By your description it sounds like your image was underexposed, printed too dark or a combination of both. Also, your subjects may have simply not had enough separation between the two black items. Think about it. Soft black coat, and soft black dress. Very similar, right? In portrait photography we use lighting coming from different directions to create highlights that separate adjacent dark areas. On camera flash only lightens the overall look of the scene. It has no direction from the cameras point of view so you can't expect it to create much separation for you. If the coat was leather, you might have seen some highlights in the smooth surface that would help created some separation but with two soft black materials, it's more difficult with just an on camera flash. If you had a good exposure on your film I suspect that you probably have SOME separation that was lost in the printing. Look at your negs with a loop and you should be able to detect separation in the area you are concerned about. If not, then your exposure is probably a little on the low side. Use your cameras controls to adjust for more exposure. One third to one half stop would be a good place to begin.

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