Your Eyes are a Miracle, Your Camera is a Machine

(This is lesson 2 in my How It’s Done Series)

The first lesson was primarily a downer. I’ll try to win you back with a compliment. You have beautiful eyes. No, I’m not just saying that so you continue reading my boring camera lessons. I really mean it, and I want to make a point. Your eyes are amazing instruments created through millions of years of evolution (or god — depending on your state of mind). A camera does not come close to the sensitivity and flexibility of your eyes. More importantly, your eyes are connected to the best image processing computer available, a human brain. Your brain adjusts contrast and exposure so quickly that you don’t even notice it’s happening. Have you ever looked through your eyes and said to yourself, “Hey, this scene could use some more contrast, or maybe it needs a saturation boost.”? Maybe if you were an eagle in a previous life you might have those thoughts from time to time, but most people take their vision for granted and never give much thought to the fact that there are other ways to perceive light than the way a human eye does.

Here is the most difficult concept of my entire “How it’s Done” series, and possibly the heart of the art form known as photography: A CAMERA DOES NOT SEE LIKE A HUMAN EYE (capitalized for emphasis, not yelling). First, the obvious differences, your eye sees motion and your eye sees in three dimensions. Your camera records a split second of light and sees in only two dimensions. Some of the more difficult to understand (frustrating to beginners) differences between camera and eye are dynamic range, perception of light temperature, and contrast.

Let’s start with dynamic range. What is dynamic range? It is the range of what is visible between complete darkness and bright white highlight. Your eye has almost twice as much dynamic range as a digital camera. On a sunny summer afternoon your eye can see details in the shadows beneath a tree and also see the bright white puffy clouds in the background. A camera can’t. Your camera only has enough dynamic range to see inside the shadows or the white puffy clouds, but not both at the same time. Below is an example of a photograph of a shady area on a bright summer afternoon. When I took this photo my eye could see details in the shadow that the camera couldn’t. By looking at this photo can you tell what color the woman’s hair is? I can’t, but if you were standing there next to me when I took this photo you would have had no trouble answering that question or telling me the brand name of the stroller by reading the lettering on the stroller’s sun visor. The stroller in this photo is so dark you can’t even see the lettering on it. The next lesson is going to be explain exposure so don’t get worried if you don’t understand my next point. What if I would have exposed this photo for shadow detail instead of exposing for the background? If I would have lightened the exposure so you could see inside the shadows then the background would turn bright white (over exposed). Do you now believe me that your eye is more sensitive than your DSLR? If you had to exchange your eyes for two DSLR image sensors you would live in a world of blinding highlights or impenetrable shadows. Walking in the park would become an adventure. You would have to choose between seeing in the shade or seeing in the sun. You can’t have it both ways. The dynamic range of a DSLR sensor is much smaller than your eyes.

Another major difference between your eyes and a camera is the perception of color temperature. Every light source has a different color temperature (color cast created by the frequency of the light emitted from the source). Incandescent lights cast a yellow/orange light. Florescent lights give off a blue/green glow. The sun is mostly neutral, maybe a little yellow. You might notice these casts if you pay close attention, but your eyes combined with your brain do a marvelous job eliminating color casts caused by various light frequencies. When was the last time you walked into a florescent lit store from a bright sunny afternoon and said to yourself, “Man, these lights have a horrible blue cast.”? Probably never. Your eyes adjust for color casts instantly, and they can even adjust for multiple casts in the same viewing area. Digital cameras handle color temperature much less gracefully than your eyes. Your camera has a white balance setting that you can set for a various situations. Your camera’s white balance can be set to auto, tungsten, sunny, cloudy, florescent, ect. These settings will eliminate a color cast from a standard tungsten or fluorescent bulb, but they don’t work well if your light source is anything other than what your camera’s engineers called average. That means almost every light source is going to give you a color cast. Fortunately there is a great solution to this problem. Shoot in RAW format. When you shoot in RAW you set the white balance in photoshop. Rather than relying on the rigid in camera white balance presets you set your white balance via the RAW converter. You can easily tweak the settings and get exactly the right white balance. Sounds complicated, right? Don’t worry – there is a camera RAW lesson coming in the future. All you need to know right now is that your camera sees color temperature and your eyes don’t.

The last concept I am going to cover in this lesson is possibly the most important because it is the first step to developing a good photographic eye and a sensitivity for light. It is so important that it will be talked about again and again throughout this series, and it might even get its own article. For now, I’m just going to give you an introduction so that you can get started developing your photographers instincts. I call this most important idea “the black point light point rule”. Here is my definition of the black point white point rule: For every scene you look at (with a couple exceptions that are just as important as the rule to be discussed later) your eye automatically sees the darkest spot as black and the brightest spot as white. What does that mean? No matter what you look at you are going to see the darkest area as complete black and the lightest area as completely white. Your eye is constantly adjusting contrast to its maximum so the the brightest spot of whatever you might be looking at is white and the darkest shadow is black.

Here is a sample of what I am talking about – the cup of ice water is sitting on a glass topped desk and lit by nothing other than window light. I marked the white point and the black point. Now, try it out for yourself. Look around your room and see if you can spot the white point and black point as your gaze moves around. No matter what your field of view you should be able to pick out a white point and black point. Practice picking out the white and black point whenever possible. You can do it when you’re walking the dog, brushing your teeth, or sitting in a boring meeting. Once you’re really good at it you will be able to pick out the black and white point without even thinking about it. It will be second nature. When you are really, really good you’ll be able to pick out the black and white point and know how far apart they are in terms of dynamic range. You’ll know whether a scene will fit inside you’re camera’s limited dynamic range with just one glance. That’s the goal. The next couple lessons will explain exposure so practice finding black and white points for now and get a jump on the competition.

Like every rule my black and white point rule has some exceptions. In certain situations you won’t be able to find a black or white point. There is no black point when you are looking at a polar bear in a snowstorm, and there is no white point in dimly lit areas. I’m typing this at night – in a room lit only by a 40 watt bulb. There is no white point when I look around the bedroom right now. It is important that you learn what type of situations will be missing a white point or black point. Play the “find the white point black point” game a lot. Get good at finding the exceptions to the rule. It will help you later when we start talking about exposure, and it will really help you when we start working in photoshop.

Above is an example where there is no white point. It was too dark for anything to be white.

The above photo is an example where there are multiple black points, and only one white point.

Are you understanding this? Practice as much as you can. Look for the white point and black point in every photo you see. You should get so good at finding white and black points that you don’t even think about it anymore. You’ll see a photo or a scene and you will know what is the darkest spot and what is the lightest spot without thought. The next couple lessons will explain exposure. If you aren’t understanding these concepts yet, my exposure lessons should clear everything up. Feel free to leave a question or comments. It’s hard to write about abstract concepts. I want to know if I’m getting the point across.

Click here to continue to Lesson 3