The Light Meter, Pt.1 The Basics
Hi and welcome to my blog. Today I want to talk about the light meter. It is an invaluable tool for a serious photographer. A light meter is simple in concept, being a device used to measure the amount of light, used to make a picture. You can use that simple concept of measuring light and apply it in many ways to give you ultimate control.
(If you don’t want to hear my thoughts on knowing your craft or a few tips and want to get right to it, skip down until you see —> ***)
My philosophy about photography in general and most photographers, as well. Most photographers learn to make pictures traditionally. This means most people learn from someone showing them a setup or settings, then they apply what they have been shown. They learn stuff from a book, a video, a workshop, a blog, ect., then over time, this information gets passed around and it becomes a tradition (a tradition to making a photograph). They rely on the camera (chimping), and being able to shoot frame after frame in the hopes of making a good photo (spray and pray). They learn traditions that get them pretty far, like composition (rule of thirds), expose to the right, and some say they can effectively use the histogram to judge exposure and I will dispel that tradition. So how do you read a histogram to properly expose a skin tone? Things that make you go hmmmmm…the answer is, you cant!
The traditional way of learning is great, in the beginning, and it will get you pretty far, however, I say it’s far better to learn how to use some basic tools like a light meter, and learn some basic exposure controls that will allow you to be innovative, not traditional in your photography. Innovative thinking is where you can use the basic controls as a framework, and then, when you have an innovative thought you will know exactly how to render your thoughts into an image.
I’ll put it another way, is it be better to know what is going on and be able to create images without anything holding you back, except the law physics, or is it better to try and fill your head with recipes of setups that everyone already knows? You see, the light meter unlocks the door to innovative thinking and image making. I can’t explain everything in a single post, but I promise to explain everything over time. It’s your job to come here and try to fully understand what I am telling you. I am sorry about the long winded theories, now I will start to explain how it all works.
There are many types of light meters (analog and digital), and they all work the same way, with respect to the information they tell. A light meter is basically a calculator, that solves an unknown variable from the exposure triangle (exposure triangle is, ISO, Shutter Speed, F-Stop). You simply plug in two known values like ISO and Shutter Speed and based on the amount of Light hitting the light meter it will give you the final value, like an aperture. That’s it! Simple right? It really is simple, but you need to know your craft.
To use a light meter you need to have a solid understanding of reciprocals (see older post), they need to be second nature. You need to know aperture, ISO and shutter speeds, because the known values (controls) in lighting and knowledge of the exposure triangle is the backbone for every lighting setup you will ever make; speedlights to studio strobes and controlling them, is all the same. Armed with a light meter and the full understanding of reciprocals, ISO, and shutter speed, the world of lighting bows down at your feet, I promise. I can’t stress this enough - if you respect yourself as a photographer or photography as a craft you owe it to yourself to know this stuff.
So on with the show.
***There are two types of light meters, reflected and incident. You can buy them seperately or as one unit. In the picture above, you see the unit on the left is a Pentax Digital 1 degree spot meter, the one in the middle is an incident light meter and the unit on the right is a combination of both, an incident light meter with a spot meter built in. (Note: All of those light meters above are mine and I love them all equally).
An incident light meter will give you the proper exposure of whatever you measure, no matter if it’s black or white, any color or texture. If you use that meter it will tell you what to set the camera at and you will make a picture of exactly of how everything really is.
You see, your camera is dumb. Have you ever tried to make properly exposed image of a black wall that fills the frame? The wall will end up 18% grey, the camera will not record it as black. On the flipside if you try to take a picture of a white wall and fill the frame, again it will be 18% grey, not white. The camera needs an even number of dark and light tones in the frame to make a properly exposed image.
An incident light meter just tells you the amount of light falling on the subject. The setting it tells you will never be wrong; a black wall will be black and a white wall will be white. An incident light meter reading is the “First Lighting Control” that you will use to create every lighting setup. That reading is the base, the control that allows you to easily predict a black and white point in a scene (I will cover that in a later post).
The second type is the Reflective Light meter, also known as, a Spot Meter. This light meter works just like your camera does; whatever you point it at and measure, it will tell you the settings to render the subject 18% grey. This means that if you measure a black wall, it will tell you the settings to make it 18% grey. On the flip side, if you measure a white wall, it will tell you the setting to make it 18% grey. It sounds kind of stupid right? Why would you want to know how to make a black wall 18% grey or for that matter a white wall, grey? Here is the secret, that information isn’t what we are after, we are after the aperture reading. With the aperture reading we can predict many things.
A simple example, if we take an incident meter reading of a subject’s face and it tells us f5.6. Set the camera to f5.6 and the subjects face will be perfectly exposed. Now, we want the background to be completely white, how much brighter does it need to be? The answer is 2 1/3 stops brighter. So we take a spot (reflective) meter reading of the background and the reading is f11, what color is the background? Is it white yet? Is it almost white yet?
The answer is no, it’s grey, and not just any grey, it’s 18% grey. It’s not just 18% grey, it’s the same value as the subjects face, so we need to turn the background strobe power up 2 1/3 stops to make it photograph white. So what is 2 1/3 stops more than f11? We don’t really need to know that, but I do and it’s good for you to instantly know these numbers inside and out. So, to make the background white, we need to double the power (1-stop), double it again (1 stop), then add 1/3 stop more so we increased the power 2 1/3rd stops and the background is white with no guessing. Now where do we need to go to make a black background? I know, I know, eww eww eww, pick me!
I know I didn’t give all of the information needed to explain an entire lighting setup, don’t let that that bother you, I am trying to give you a taste of the controls that I will speak to in future episodes. The controls are the key - think control and concepts.
Imagine being able to create a vision in your mind, set up some lights, put a subject in the frame, take a few measurements, go to the camera and press the shutter one time and you have created your vision…with no guessing. That is some powerful stuff! There is a little more to it than that, obviously, but you get my point. Armed with a simple tool (a light meter) and some knowledge and you can be innovative with your lighting.
In future episodes of “The Light Meter” I will provide more information, so you can start to fully understand it’s use. I will teach you how to set one up. I will cover the lighting controls you need to know in order to fully take control over your lighting. And one last thing, if anyone ever tells you “your camera has a light meter built it, why do you need a light meter?”, slap them upside the head and tell them, how the heck does the camera’s light meter measure flash? Answer: It can’t.
I want to thank those that took the time to read this post. You are the ones that are serious about learning your craft, and my knowledge is your reward. I love to teach, and I hope you like to learn. If you have any questions or comments, please take time to post the below. I will respond to them as soon as I can. I hope you have a great day. Thomas Shue.
Man 1658 words is a lot for a Basic Light Meter Post.