A while ago I got into a discussion that got me thinking. You are probably aware that the softness of the light is affected by the size of the light source and the distance between the object and the light source. But what happens if I use a translucent umbrella aimed at the subject and compare it with an umbrella that is turned away from the subject and that the light bounces against.
I figured that with a translucent umbrella, the convex shape of the umbrella will make a smaller part of the umbrella surface illuminate the model. The rest of the light from the umbrella will illuminate the surroundings. If you turn the umbrella away from the model, the light characteristics of a reflective umbrella will have the same softness or maybe even. be even softer than a translucent umbrella of the same size.
In order not to just stand and take a chance, I had to test my claim. To start the test, I placed a translucent umbrella as close to the model as possible without the umbrella interfering with the composition of the image. Then I turn the flash/umbrella around with the tripod in the same place, which means that I keep the angle to the model in both pictures.
I chose to use the same transparent umbrella for both test images. This means that the light will bounce differently in the studio depending on how I use the umbrella, but it is quite a large room and we are interested in how the gradation between light and shadow looks like. We disregard the possible smoothing effect. As I work with the flash so close to the model, there will not be a significant difference with light bounce in the studio. If I had used a reflective white umbrella, we would only get more light on the model (= different exposure) but the softness of the light would be the same.
Well... the first tests were a lighting setup where I let the light of the flash pass through the umbrella fabric and with the umbrella as close to the model as possible. I have directed the light so that the middle stick of the umbrella is aimed slightly in front of the nose of my model, which creates the smoothest possible gradation from light to shadow.
Below you see a sketch. The blue line in the umbrella is to symbolize roughly how large an area actually illuminates the model. Other light will spread around the studio and illuminate both photographer and background.
I was careful to measure the light with the light meter positioned right at the bridge of the nose so I could set the same brightness on the model for test #2. In addition, you must be careful to position the flash head so that you illuminate the entire umbrella.
Why get a big umbrella if it doesn't shine? Turn on the setting light and see how the light spreads in your umbrella. Pull the umbrella out a little to increase the spread of light or push it a little into the umbrella holder so that the light does not spill out to the side of the umbrella.
For the second test, I left the flash stand in exactly the same place. If it becomes as soft or softer from this position, then there is room to move the flash even closer and create even softer light. When the flash reflects in an umbrella and the concave side of the umbrella is directed towards the model, the entire surface of the umbrella is used to create softness in the light. This makes the light source larger but it is also further away.
Both factors will affect the softness of the light and there will also be a difference in how quickly the light fades on the model. In test 1, we see that the collar and shoulder of the shirt are the brightest part and then the brightness decreases quickly. In picture 2 below, there is a larger surface of the model that is evenly exposed.
The light will of course spread on the background and in the room, but what happens in the model's face if we compare with test 1? In fact, remarkably little in terms of the softness of the light. Despite the increased distance, we retain the softness of the light.
So what can we learn from this? What I personally take away from this is what an amazing tool this simple light shaper is. We can place the umbrella really close and get a clear change in exposure. Or place the umbrella further away and get a more even exposure thanks to the umbrella's spreading effect.
Especially when the umbrella is illuminated, the convex shape will give a slow "fade" out into the unlit area. This makes the transparent umbrella a perfect light source when you want to mix the flash light with other light such as e.g. daylight outdoors or perhaps for portraits in an office.
However, you do not create softer light with a translucent umbrella than a reflective umbrella of the same size.
Translucent umbrella.
The light source close to the model and thus rapid exposure variation/loss of light.
Reflective umbrella.
The light source is further away, which gives a more even exposure and also a slightly brighter background. However, equivalent softness on the light.
If I now decide to do the same test again but lift the flash further away from the model, what happens?
With the distance, the difference between reflective or translucent umbrella will decrease in terms of hardness/softness of the light (Graduation between illuminated surface and the shadow). However, the fading from the light source to other existing light or unlit surface will be milder from a translucent umbrella.
With this newfound knowledge of how the hardness/softness of the light behaves, why do I need different umbrellas?
Just like other light shapers, it of course depends on what you want to achieve. In my case, I would choose translucent umbrella in the situations where I want to blend the umbrella light seamlessly with other light, regardless of whether it is flash light, daylight or other fixed light in order to create the illusion of "natural light". With a translucent umbrella, I get a fade that makes it next to impossible to tell where the flash ends or begins, especially in combination with other light.
In other words, outside of the studio, translucent umbrella is my "go to" light shaper if I only have to choose one. For my part, the Deep transparent Umbrella 105 cm is a great choice, easy to take with you and with its deep feature, the light fades out even more discreetly. I usually use a reflective umbrella when I want to use the power of the flash as efficiently as possible and still have all the advantages of using an umbrella. Just the opposite of how a deep transparent (translucent) umbrella tones out the light well, a deep reflective (reflective) umbrella will collect the light where I direct it and further enhance the advantages a reflective umbrella has.
To create softness or hardness in the umbrella, it actually doesn't make much difference if you choose a translucent or reflective umbrella. Hope this test made things a little easier for you to choose which umbrella to use and when. It has done that for me.
/John