Spekular Fundamental Lighting Principles: Part Two
I’m building this series for a good reason. I feel like there is a lack of understanding of how light works, and I want to bring you principles that I never leave home without. These are the Spekular Fundamental Lighting Principles. These are scientifically backed ideas that apply to lighting specifically. I know without an ounce of doubt that if I encounter a problem on a shoot, using these principles will allow me to solve it. However, these being my major fundamentals of lighting, I couldn’t imagine fitting all my “knowledge” into one post. Hence, I had to break this series up into 3 parts.
Today, we’re introducing flash.
I completely understand how flash can be intimidating. We’re introducing a light source to the photo that isn’t naturally there. We’re not sure how it will turn out until the image pops-up on the back of LCD. Plus, we usually relate flash to that nasty little bugger that pops-up on your SLR and creates harsh shadows and turns your loved ones into red-eyed killing machines.
Let’s change the way you feel about flash. I’m going to introduce a situation to you using ONLY flash for use in studio type settings. I’m going to explain to you three very easy principles I use to change exposure with manual powered flash.
First you’re going to need a few key pieces of gear. You can check out what I recommend here, or find these yourself:
A light stand. This is going to be one of your flash unit’s best friend. It will defend it against all gravity and elevate it anywhere between 2-7 feet. I do have one very important piece of advice here: don’t buy a cheap light stand. You’re putting a big investment (your flash) on top of your light stand. If you purchase a cruddy stand, you might end up with a flash that knocks its head against the ground.
A swivel. This is going to be your flash unit’s other best friend. This little guy is going to allow you to tilt, rotate, and position your flash in any direction you wish. Again, you can find these pretty easily, but don’t buy cheap. Make sure you get a swivel that is all metal; you don’t want your flash to take a tumble because you bought a cheap plastic swivel that broke. Most (if not all) swivels will allow you to attach an umbrella and increase your light source size.
A trigger. This is always a hot debate with photographers. You can sync your camera with your flash off camera with anything from a very long cord, to an expensive radio device called a trigger. I prefer the radio trigger method. No wires, no mess, no worrying about shorts in the wire. Again, if you want maximum reliability, invest a little more money. If you just want to play around with off camera flash, feel free to spend a little less.
A modifier is optional. Some people shoot bare flash, while some prefer to modify the light. There are so many modifiers to choose from and they all do a different job. I like to compare modifiers to tools in a toolbox: each one is built for a different purpose. I use a variety of modifiers, anything from grids, to softboxes (I’ll do a post in the future on the features of different modifiers.)
And, of course, you will need a flash. More than likely, your flash will be the biggest expense. Buy something you’re comfortable with, that you can afford, and that is reliable. Don’t be sold on a low price, and don’t be sold on useless bells and whistles. I use a very basic flash that is manual only (no TTL) and I’m going to show you how easy it is to operate a flash manually. If you need a run down of the difference between TTL and manual check out this page.
Now that you have an idea of the gear you need, let’s talk about how to use it.
I follow three primary principles with flash photography. Before I explain those to you, we need to understand one thing: forget shutter speed. Shutter speed will not affect the amount of light coming into your camera with flash. Your flash is triggered at an extremely high speed (the time the light appears and disappears is around 1/20,000 of a second) and regardless of what you set your shutter speed, it will capture the same amount of light. Your camera’s shutter is only capable of syncing so fast with flash—across all brands, this shutter speed is on average about 1/200th. So, simply set your shutter speed to 1/200thto drown out the ambient light—and forget it.
Now the three principles I live and die by with flash:
- I have the ability to move my flash closer and farther away. Based on what we know about inverse square law in part one, this will change the exposure.
- I have the ability to change my flash unit’s power output. Turning the flash power up or down will change the exposure.
- I have the ability to change my aperture. Aperture is going to be only way to change exposure in camera, because we know from the paragraph above, shutter speed will not.
So now, I have three options to change the exposure. To start, I’ll begin with a very uniform method. I’ll begin by just setting my flash down in the direction I want it to hit my subject, set the power to 1/16th on the flash, and set my aperture to f/8. Then I’ll take a shot. After this I can check the histogram on the camera to see if it was underexposed or over exposed. Here’s where I apply the principles:
If it is overexposed:
- I can move my flash further from the subject OR,
- I can turn the flash power down OR,
- I can increase my fstop (or close down the aperture)
If it is underexposed:
- I can move my flash closer to the subject OR,
- I can turn the flash power up OR
- I can decrease my fstop (or open up the aperture)
After applying one of the three principles, I’ll take another shot and check the histogram and image to see if I’ve reached the desired exposure. Each one of the principles has its advantages and disadvantages:
- Changing the flash-to-subject distance will either increase the light source size (bringing it closer) or decrease the light source size (moving it away)
- Changing the flash power output will either increase or decrease the recycling time (the amount of time it take the flash to recharge). Increasing power will increase the amount of time, while decreasing power will decrease the amount of time.
- Changing my fstop will increase or decrease depth of field. A larger aperture will have a shallow depth of field while smaller aperture will have a larger depth of field.
I take all of the advantages and disadvantages into consideration when I need to adjust exposure.
Below is a very easy to use diagram to explain everything I just wrote out.
So let’s take this into a real world application. I chose to photography my niece, Hanna. At 4 years old, she is already a firecracker of cuteness and attitude. She was more than willing to model and jumps at any chance when asked. I knew I wanted to have the light fall on her from above, but still wanted it to hit her face. So I decided on positioning a flash with a Large Rogue Flash Bender (with diffusion panel) just above camera position. First I needed to determine that there was no ambient light contaminating the image, so I took a shot at 1/200th to ensure that:
Then using the methods and principles I described, I started with this image:
Slightly underexposed, not a problem. I don’t want to increase the light source size, because the flash is already so close to her, and I don’t want to open up my aperture because I like the depth of field that I’m getting, so I’ll increase my flash power up two notches from 1/16th to 1/4th. I take another shot and get this image:
Now I’m overexposing. I could get frustrated, but I know I still have room to adjust. Using the same logic from above, instead of changing the flash-to-subject distance or changing my aperture, I’ll just increase flash power up one notch to 1/8th.
Good, now I’m on track to getting the final image. At this point I’m using one light, but I want to add one more light to fill in the dark shadows under her neck and nose. Plus, it would be nice to add a second catch light in her eyes. So now I’m just going to add another flash with a Medium Rogue Flash Bender at the lowest power just under the camera pointed towards her. I don’t want it to be overpowering, so I’ll simply set it on the lowest power setting, 1/64th.
Done! Not only is it incredibly easy to use manual power flash, but you also have way more control over the light in the image. If you remember the three primary principles and continue to use them, they will become muscle memory. You’ll use them to solve problems and obtain the light you want to create great images.
There’s more to the Spekular Fundamental Lighting Principles. I’m glad you’ve made it this far! Stay tuned for Part Three, when we use flash units in addition to the ambient light that we’re familiar with to capture images that create impact.