Umbrellas 103 for Beginners: Light Fall Off and Comparing Different Umbrella Sizes

Umbrellas 103 for Beginners: Light Fall Off and Comparing Different Umbrella Sizes

We’ve studied how direction and angle can drastically change the quality of light produced from your umbrella. We have also seen examples about how distance can change the umbrella light falling on your subject.

Now it’s time to look at the big picture. Let’s take a peek at how our umbrella is actually producing light across the whole image, not just the subject that you chose. In Umbrellas 103, we’re going to study fall off, and compare the type of light produced by four different shoot thru and reflective umbrellas.

If you’ve ever wondered why you might use a giant umbrella instead of a small, collapsible model, this article is for you!

The light you have created with the umbrella is interacting with your whole image. For our example images, I’m supposing that you are creating a portrait of a single subject and relying on the umbrella to create all of the light capture in the image. I’m lighting our model Manny to an exposure that I decided I liked, but the same concepts will apply to the exposure you might choose for your image. I photographed each example at ISO 100, 1/125th of a second shutter speed and an aperture of f/8. The flash and umbrella remain at a 45-degree angle camera left, and a 45-degree angle downward to the subject.

While we have lit our subject, we now need to note that we are also lighting our background with the same umbrella. As you will recall from Umbrellas 102, it’s important to understand and construct your light utilizing ratios. Remember, it’s inaccurate to just refer to the light as full power or quarter power. Rather, we need to meter and read our light as stops of luminance within our composition. That phrase sounds a little confusing, but never fear, because we already started to learn about this in Umbrella 102. Our little discussion about the inverse-square law is going to help us decipher the spill light created by our umbrella.

Along the way, we are going to compare the look of a few different types of umbrellas that are common to the marketplace: the trusty 43-inch white umbrella as a shoot thru and reflective light source, the 60-inch white as a shoot thru and reflective source, a 43-inch silver umbrella as a reflective source, and a 7-foot white parabolic umbrella as a shoot thru and reflective source.

Close Background and Umbrella Light

60-inch umbrella light, with very little distance between our subject and background.

We’re going to start supposing that you are lighting with your umbrella and placing your subject right next to your background. You might try this technique if you want to keep a close ratio of light between the subject and background. But really, what does that mean? Here’s where things get really interesting with your umbrella.

You are asking the umbrella to light your subject. Here, Manny’s face in the middle of the frame. Inverse-square law tells us that we will lose 75% of the luminosity produced by the flash and umbrella as the light travels over the first two meters. Since our subject and background are on the same plane (front to back within our frame), there is barely any fall off to see.

Now, that’s not to say that there is NO fall off in the image. There is a bit of vignette to note. You should notice that as the light travels from left to right, there is a change in the amount of light produced by the flash and umbrella. The fall off is less prominent on the left side of the image, but I bet you already know why! The umbrella light is closer to the left side of our background, and thus, the light is traveling a shorter distance to illuminate the background.

Let’s take a look at our hard light source from the same position. You can really see exactly how much of a difference the umbrella can make regarding diffusion. There’s about -2/3 stop light on the left part of our frame, and -1 1/3 stops on the right.

Hard light, with very little distance between our subject and background.

Seven Foot Parabolic

7-foot parabolic, reflective position.

There’s certainly nothing wrong with placing your subject right next to the background, but let us suppose that you want to try an image with some space between your subject and your background. Here are some examples I set up to give you a look at how the inverse-square law will play into that. For these images, Manny is now exactly two meters from the background. We are still working at f/8 for our intended exposure on the subject.

So with that distance between the subject and background, you can see that our seven-foot parabolic umbrella as a reflective light source produces a very even light across both Manny and the background. Corner-to-corner, the background is dancing around -2 stops, due to the distance we placed between the subject and background paper.

Up next is the parabolic in shoot thru position. To me, this light is still very large and even, though not as even as the parabolic in reflective position. There’s more drop off here in the corners and edges, with the background nearing -3 stops. This particular setup seems to produce a large but focused light on the subject, and it appears that less light reaches the background. I know the math on the inverse-square law states differently, but in real life not all light sources adhere to the formula all the way across the composition. That’s part of the fun!

7-foot parabolic, shoot thru.

PROS/CONS of the big parabolic: It’s big, soft light that is very even from edge to edge. However, this modifier is massive. If you need to work in a small space, good luck getting this into the room. I’m not a fan of using these big guys as shoot thru sources.

60-inch White Umbrella

60-inch, reflective.

Here’s a pair of images to illustrate the quality of light the 60-inch white umbrella can produce. For the first image, our reflective position produces a nice, soft light across the subject, while our background sits around -2 stops. Fall off with the shoot thru is fairly dramatic, and the background falls to a -3 to -3 1/3 exposure compared to our subject.

60-inch, shoot thru.

PROS/CONS of the 60-inch umbrella: Similar to the parabolic, it’s big, soft light that is very even from edge to edge. It is still a big umbrella, but this is much easier to manage in smaller spaces while retaining wide and soft coverage.

43-inch White Umbrella

43-inch white umbrella, reflective.

Our pairing of the 43-inch white umbrella is up next. This one is particularly interesting to me. I think this umbrella produces a great look across the subject’s face, while pushing nice light across the background. You get just enough of a ‘natural’ vignette to seal the edges of your frame. However, you could produce a similar look by moving some of the other umbrellas closer to the subject, or moving the subject further from your background. Background is near – 2 1/3 stops in reflective position and -3 stops in shoot thru position.

43-inch white, shoot thru.

PROS/CONS of the 43-inch white: Very compact, so this one travels well. Also, the version of this umbrella with a collapsible shaft will allow you a chance to experiment with placing this umbrella very close to the subject as a shoot thru and reflective source. However, the coverage from this umbrella is not even across a wider composition, so you will have to manipulate the fall off to your liking.

43-inch Silver Reflective Umbrella

43-inch silver, reflective.

Last up for our comparisons, here’s the 43-inch silver reflective umbrella. Obviously, this umbrella can only be used in reflective position. This light looks fairly similar to the hard light example to me. Compared to the white umbrellas, the silver umbrella produces a sharper shadow, but still provides some spread for the light. The upper left corner of our background falls to -4 stops, while the bottom left sits near -3 2/3.  Our left side ranges from -2 1/3 to -3 stops.

PROS/CONS of the 43-inch silver: Again, the coverage from this umbrella is not even across a wider composition, so you will have to manipulate the fall off to your liking. I like this umbrella when you need to maximize the power output from the flash while giving a nice ‘punch’ to the light. To me, this umbrella retains an interesting combination of hard and soft light. If you are looking for a classic, soft light, you ought to try the white umbrella first.

Our last installment of the Umbrella series is up next. We will address some reader requests, like comparing umbrella light to other popular soft box options, and talk a little about feathering the light from your umbrella.

Log in or register to post comments

5 Comments

Kian McKellar's picture

I love the concept between these umbrella articles but I feel that there has to be a better way of comparing the different sizes. For instance the large pictures strung out through out the article make it harder for me to place them side by side and see the small details that change with the different sizes. Sorry to criticize but I feel that the content is good but your message is being lost in delivery.

Aaron Ottis's picture

Hey Kian,

Thanks for the feedback. I'll work up a side-by-side chart like 102 and add that into this article. Some people process information differently than others. Thanks for asking! I'm sure other readers will benefit, too.

animated GIF is a great way to show comparisons since the the frame doesn't move its easy to see the differences in a sequence. Just another idea.

Anonymous's picture

Magical

Scott Richardson's picture

Fantastic article - have been looking for a comparison like this for some time - thanks!