light quality

What information lurks in the shadows?

Only the Shadow knows.

And he has something to say! Shadows are a very important piece of our photographs. Shadows help define our subject. They help set the mood of the photograph. They can hide things we don’t want to show. They can tell a story about how a scene was lit. And that’s what I am talking about today. What can we see in the shadows?

Here are my descriptions for the 14 images on the right (click on the image for a larger version):

  1. Standard 7-inch metal dish reflector
    Notice slight double-edge to the shadow due to the flash tube being slightly brighter than the surrounding reflector.

  2. Standard 7-inch metal dish reflector with one layer of diffusion material
    Contrast is lower from light bouncing around the room, shadow edge is more homogenized by the diffuser. The shadow edge is the same, no extra softening from the diffusion, just a brighter shadow.

  3. Standard 7-inch metal dish reflector with two layers of diffusion material
    Very similar to #2 but needing more flash power. Extra diffusion did warm up the color. Still has the same edge with no additional softening.

  4. Standard 7-inch metal dish reflector with 10-degree grid
    Narrow beam of light doesn’t hit walls, ceilings, etc. (environment), so more contrast. Still has the same shadow edge quality, just a darker shadow and restricted coverage on the background.

  5. Standard 7-inch metal dish reflector with 10-degree grid plus a layer of diffusion
    Brings us back to what we had in #1 or #2, but required 5 more stops of light power to maintain the same exposure. Don’t put diffusion in front of a grid! It negates the effect of the grid at the cost of a lot of your flash power.

  6. Deep Zoom 11-inch reflector
    Narrower light been from the deep reflector gives a darker shadow, somewhat similar to the grid in #4, but like #1 the shadow edge is doubled because of the difference in efficiency between the light direct from the flash tube and the light bounced off the walls of the reflector. Diffusion would help homogenize the shadow, but will also take away some of the contrast.

  7. Deep Zoom 11-inch reflector with 10-degree grid
    Even less environmental bounce producing a darker shadow.

  8. 1x3 strip box in vertical position
    Narrow modifier produces little shadow along its long dimension (up/down here) with much more shadow along its shorter dimension (left/right here).

  9. 1x3 strip box in horizontal position
    Rotating the narrow box moves the shadows. The left/right shadows are a little bit tighter while we now have up/down shadows. This is especially noticeable on the light stand holding the silhouette. In #8 it casts a wide shadow, while in #9 the wide pattern wraps around the narrow object and there is virtually no shadow.

  10. 2x2-foot square softbox in close at 3-feet
    This softbox has both an inner and outer diffusion panel. Shadow transition is soft

  11. 2x2-foot square softbox backed up to 6 feet
    The box gets smaller in relation to the subject when moved back.The shadow gets a harder and more defined edge. The background brightens up slightly (depth of light, inverse square law). More light bounces around the room picking up some warmth from the wooden floor.

  12. 2x2-foot square softbox at 6 feet with an extra layer of diffusion
    Shadow quality remains the same, but image picked up some warmth from either the wood floor bouncing in or from the diffusion material (or both). Requires more flash power.

  13. 46-inch Photek Softlighter umbrella WITHOUT the diffuser
    Large, round light. Even shadows all around. Background is brighter than #14 due to longer light path and depth. Although the umbrella is 36 inches from the subject, the light path is from the flash to the umbrella (24-inches) and from the umbrella to the wall (36-inches) so the distance of light is like having a forward facing light at 5-feet away instead of 3-feet, as you would get with the front diffuser (see #14).

  14. 46-inch Photek Softlighter umbrella with the diffuser
    Adding the diffusion cover has a slight effect on lightening the shadow density. Background is slightly darker as the light source (the diffusion panel) is closer to the subject. The closer the light is to your subject, the darker the background will be.

All the photos were metered to give the same exposure. In most cases the aperture remained the same (f/4.0) and the flash power was adjusted to maintain correct exposure. The exceptions are the exxamples with the Deep Zoom reflector, as it was very efficient and I could not lower the flash power enough so I had to stop down the lens to f/7.1. 

The main take-aways from this lesson is that the shape of your modifier determines the shape of the shadows and the size of the light as seen by the subject determines the size of the shadow width or the quality of light, that is hard or soft. Diffusion, along with the environment, controls the shadow density or contrast. Adding diffusion directly to a light, where it doesn’t make the light any larger, does not soften the light. It is a very subtle, but important concept. Diffusion does homogenize the light, making it more even across its field. And, depending on the environment, fills in the shadows making them less dark by bouncing off the walls, floor, ceiling, and other surroundings. Don’t confuse contrast with quality.

As I said, the difference can be subtle. Here we have three photos to compare. The first (A) was lit with a standard 7-inch diameter silver metal dish reflector. It casts a hard edged deep shadow. Next, I taped a sheet of diffusion material over the reflector (B) and you can see that the edge shape and transition (quality) has remained the same. What changed was the depth or darkness of the shadow (contrast). The diffusion spread the light around the studio and made the shadows lighter in tone, but the edge didn’t change because the light size didn’t change. For the third photo (C) I switched to a 20-inch diameter light modifier without diffusion and you can see here that the edge got softer and the transition got wider as the light was able to “wrap” around the subject for a softer light quality.

contrast-vs-quality.jpg

Now let’s look at what happens when we keep the same small 7-inch diameter reflector but add single and double diffusion. The first sheet of diffusion material makes the shadow brighter and also homogenizes the shadow edge so there is no longer a double-shadow (from the flash tube and the reflector not being equal in brightness). Adding the second layer of diffusion slightly lightens the shadow, but not appreciably. It does not in any way soften the light.

multi-diffusion.jpg
triple-diffusion

I can anticipate a comment and question. That’s all well and good for diffusing a small light. I am using a Photek Softlighter and want to double (or triple) the diffusion on that. What happens there? Let’s take a look! Here are four examples starting with the Softlighter umbrella on its own without the diffuser. Next is with the diffuser. Then for double diffusion I hung a roll of diffusion material in front of the Softlighter to double-diffuse it. Then I doubled that up to make it triple-diffused (see the photo on the right). Adding the diffusion panel to the bare umbrella actually limits the spread of the light and makes the shadow a bit darker. Adding additional layers of diffusion on top of that brighten the shadows ever so slightly and start to add some warmth to the color. But again, no change in the quality/softness of the light from extra diffusion. The size of the light remained the same.

This environmental bounce can also cause color casts if the room isn’t neutral in color. In a larger studio, or in a studio with black walls, ceiling, and floors, or in an open field the changes in contrast on the subject with or without diffusion and grids will be much less noticeable.

 

 

Well, this brings us to the close of another year. 2018 has been quite a year for me. The biggest event was the passing of my 98-year-old mom, Rose, in August. Thanks for everything you have done for me and for all the support for my taking my own direction in life. I could not have had a better mom. Rest in peace.

So, here is looking to a bright new year with new challenges and accomplishments. I wish you all a Happy New Year! Stay safe and be well.

Cheers!
John














Don't confuse contrast with quality of light

One more time with feeling!

We are coming to the end of my 10-week intro to studio lighting class and I still see confusion between light quality (determined by the size of the light) and contrast (determined by the environment).

Basically, contrast is the depth/darkness/density of the shadows. It is controlled by the environment. If there is a lot of light bouncing around off of the walls, ceiling, floor, or other nearby surfaces the shadows open up. Adding a diffuser to your light spreads the light out to bounce off all those objects to lower the contrast. The bigger and darker the environment you are photographing in, the more contrast you will have. Narrow beam reflectors and grids can be used to control spill (the opposite of adding diffusion) and maintain or increase contrast when working in smaller spaces with light color walls, ceiling, etc. Please, do not add diffusion material in front of your grids!

Quality of light is the transition from highlight to shadow. It is controlled by the size of the light. The larger the light is as seen by the subject, the softer the light is as the light hits the subject from many angles and provides its own fill light. Yes, it lightens the shadows, but the main thing is that it does away with the abrupt edge that you get from a smaller/harder light. 

Adding a diffuser such as a scrim or a shower curtain some distance in front of a small light source turns it into a larger source, making the light softer. But diffusion right on the light (which doesn't change the size of the light) will not change the quality of the light. While the shadow is less dark, it still maintains a hard edge if the light source is small.

Some pictures to help explain…

Feathering your light

For my fine feathered friends!

feather.jpg

Back again to help clarify studio lighting terms. This time I am taking on the concept of feathering. Feathering is pointing the light ahead of your subject instead of straight on to your subject. Feathering usually produces a nicer looking image. People often say a "softer" light on the image, but that isn't quite correct. Remember that the quality or character of light is determined by the size of the light in relation to the subject. You see this in the shadow edge transition. The larger the light source is the smoother the diffuse highlight to shadow transition is and the softer the light is.

Let's take a look at what happens when you feather the light. Here are photos of a 2x2-foot softbox straight on and the same softbox feathered off to one side. What do you notice first? I hope you see that the feathered light is SMALLER than the direct light. So, if the light remains the same distance from the subject, it is potentially slightly harder when feathered. But at the same time, it spreads out more across the face of your subject, giving a more pleasing look. 

Straight on the softbox is larger than when feathered

Straight on the softbox is larger than when feathered

Hard Light

Working with a softer (larger) light source it isn't so easy to see what is happening. Let's start with a harder light. This time a 7-inch standard metal dish reflector. 

7-inch reflector straight on and feathered 

Take a look at the 3 points labeled in the photo. A (the nose), B (the lower lip), and C (the ear).  A is the same brightness direct and feathered. Why? Because it is a specular reflection and is the same brightness as the light source, no matter the distance. If the light was moved in closer the brightness would stay the same but the reflection would get bigger. If the light source was moved back the brightness would again be the same, but the reflection would get smaller. The feathering doesn't have much of an effect here.

B is somewhat similar with the small hard light source. Basically the same straight on or feathered. At point C we can see that pointing the light more in front of and across the subject a little bit of light catches the ear. I would probably retouch out that little highlight on the ear. 

Go back to point A and the nose. This time look on the shadow side of the nose. The edge of the main dark shadow is about the same. With the feathered light the shadow is not as dense, but the edge transition line is pretty much the same. The feathering lowered the contrast, but didn't make a softer transition. It didn't soften the light.

Soft Light

Now let's work with a softer light. This time a 2x2-foot softbox. 

24x24-inch softbox straight on and feathered

The differences are more subtle, but they are there. Look at the same three points as before. The brightness of the specular highlight on the tip of the nose is the same brightness straight on and feathered. But this time there is a difference in point B on the lower lip. Feathering the light changed the shape of the wide highlight on the lip, but the brightness is still the same. The larger light also allowed more  light to reach the ear than with the 7-inch dish above. 

Again, I invite you to look at the shadow side of the nose. There is very little difference in the shadow edge transition. Feathering did not make it softer.

Comparison sliders drag to the left to see the feathered light, drag to the right to see the direct light

Hard vs Soft

Below are the feathered light images with the small and the larger light sources

Comparing the 7-inch and the 24-inch light sources

Look at the same points again. A is pretty close in brightness, but the shadow edge on the shadow side of the nose is very different. That comes from the difference in the size of the light sources, not from the feathering. The larger light makes for a nicer looking highlight on the lower lip (B). If I had move the softbox back further away from the face it would have been smaller and brighter. Brighter because the rest of the face would have received less light and I would have to have compensated by turning up the power of the light (strobe) or used a longer shutter speed (constant light, which is what I used for these demonstrations). As noted above the specular highlight remains the same brightness, but I would have had to brighten up the entire image, including the specular highlight to maintain proper exposure on the face. I know that  this can be confusing. So let's look at another illustration.

Controlling the size and brightness of specular highlights

Again I am using a constant light, so I am controlling my exposure via my shutter speed. If I was using flash here I would vary the power of the flash to maintain the same exposure on the subject of the photo. With the light 40-inches from the can the highlight is thin and bright--too bright to read the text on the label. As the light is brought in closer a couple of things happen. 1. The highlight gets wider because the light is closer and therefore larger in relation to the subject. 2. I have to lower the overall exposure so the diffuse reflection of the can is properly exposed. This brings down both the overall exposure and the specular highlight brightness, bringing them closer in line with each other. In the third image the light is very close and its reflection is even less noticeable because it is spread out over a larger area and the brightness of the rest of the can has been brought up closer to the brightness of the highlight (and then the overall exposure was lowered to bring it all back to give the proper exposure of the overall subject). I know this can sound counter-intutive. Bringing the light in closer reduces the mirror-like specular reflections.

We see the Inverse Square Law doing its thing here. As the light is moved closer to the subject it falls off faster and the background gets darker. As the light is moved in closer the specular highlight remains the same brightness, but gets larger. As the light is moved in closer the overall diffuse reflection exposure gets brighter and we have to lower the intensity of the light.

BOTTOM LINE

Feathering your light can change the size and shape of specular highlights, but the brightness will stay the same. Feathering your light will help even out the exposure across your subject, but won't have much effect on the shadow edge transition (softness). Feathering your light is the right thing to do. If you want to tone down a hotspot you need to move your lights in closer. But that also affects the depth and spread of the light. So many tradeoffs in photography. More details about the tradeoffs are in my book, Anatomy of a Studio Portrait.

Thanks again for stopping by!
John Cornicello