Photography is basically working with light. When we look at something with our eyes, what we see is the light reflected off from what we are looking at, captured by our eyes, and then the image is processed by our brains. What we are trying to do when we photograph something is to duplicate what we see in our minds by capturing the reflected light off from something and storing it on film or digitally. When people start taking photographs, they are often surprised to find out that what the camera actually records is different from what they saw when they pressed the shutter release on their camera. There are a couple of reasons for this.
One is that we see in three dimensions because we have binocular vision, we see with two eyes. Each eye is capturing an image, and our brains process those images, combines the two of them into one image, and then processes the combined image even more, and that is what we “see”. The camera only sees in two dimensions.
Another reason for the difference between what we see and the image we capture with a camera is that our brains also focus in on what we are looking at, much like zooming in with a camera that has the ability to zoom in. We see a bird perched in the top of a tree, and our mind automatically focuses in on the bird and we see it quite clearly, but when we take a picture of it, it seems to be almost invisible. For some reason, our brains don’t focus in on the subject in a photograph the way it does when we are seeing it with our eyes.
The third reason for the difference between what we see and our photographs is that our eyes have a wider range of focusing than a camera lens does, and our eyes are automatically focusing on what whatever we are looking at. This happens so fast, that for the most part, we aren’t even aware that it is happening. When we look at a scene, where ever our eyes look, they focus on what we are looking at. A camera can’t do that, it is focused on one part of the scene when the shutter opens and closes, and that’s what we see when we look at the photograph. Our eyes can’t put the parts of the picture that are out of focus into focus the way they can when we are looking at the real thing.
Yet another reason is that our eyes are much more effective in low light situations than a camera is. There is a threshold of light required by a camera in order for it to capture any image at all, much higher than that our eyes require. Like looking up at the stars at night, our eyes can see the stars, they are bright enough to trigger the receptors in our eyes. But a camera requires a very long shutter opening to capture the light from the stars, and by the time the camera has received enough light from the stars, they have moved, resulting in a blurred photograph.
And finally, our brains add and subtract from the images our eyes are seeing all the time. To draw an analogy, it is if our brains are altering the images from our eyes on the fly the way that we do to photos in a software program like Photoshop. Our brains know what something is supposed to look like, and it alters the raw images captured by our eyes so that what we see is what we know what something looks like from times in the past when we have seen the same thing. No camera can do this, we can attempt to do the same thing with computer software, but our brains are much better at it, faster, and we don’t even realize that it is happening.
So, let’s go back to the beginning, photography is capturing light reflected off from things that we see, and storing the images on some media, be it film or digitally. Taking good photographs requires an understanding of the process of capturing the light, how a camera and lens does that, and the limitations of the camera and lens. There are three basic camera/lens setting used to control the amount of light that is recorded. They are the ISO rating of the film used or the camera’s sensor if it is digital, the aperture of the lens, and the shutter speed of the camera.
ISO stands for International Standards Organization, and the ISO rating came about in the days of film photography, as a way for photographers to know how sensitive a film was to light. That is a function of film chemistry, which I am not going to get into here, other than to say that the lower a film’s ISO rating is, the less sensitive to light the film is, but the better quality of the pictures recorded on the film is. The reason photographers had to have a rating for a film’s sensitivity to light was so they would know how much exposure to light the film needed, and since each film manufacturer had their own film chemistry, the manufacturers got together and came up with a rating system so photographers could compare films. With a film camera with a built-in light meter, you had to set the camera to the correct ISO number to get the exposure correct. The rating system is a complex mathematical formula no one but a hardcore photographer needs to know.
In a digital camera, the ISO rating corresponds to the film ratings, but rather than a function of film chemistry, it is a function of the electronics in the camera, the gain from the sensor used to capture the light. Unless you’re an electronics geek, you probably don’t care what the gain from the light sensor is, you just want to take good pictures.
Here’s what you need to know about ISO ratings. If you have a film camera that has a built-in light meter, you have to set the camera to the setting that is marked on the box the film comes in. In either a film or a digital camera, the lower the ISO rating you use, the better quality of pictures you can take. The higher the ISO rating the more sensitive to light the film or camera will be, and you’ll be able to take pictures in lower light circumstances than you would be able to if using a lower ISO rating. If you have a digital camera that will set the ISO automatically to adjust to the light conditions at the time, then that’s the setting you should use almost all of the time, I will get into why you would lock it to a particular setting later on.
Aperture refers to an opening in the lens of a camera that controls how much light is allowed to pass through the lens and hit the film or sensor of a camera. Because of the properties of light, and lenses, aperture also controls what is called depth of field, and also has a lot to do with how sharp pictures turn out to be.
It starts out very simply, there is a diaphragm in the lens of a camera that you can open and close to adjust the amount of light entering the camera. Think of the pupil of your eye, in low light your pupil expands to allow in more light, in bright sunshine, your pupils contract to block out the light. The diaphragm, or aperture of a camera works almost exactly like the pupil of your eye, expanding and contracting to control how much light passes through the lens.
It starts getting complicated in that the numbering system for how large the opening is inverse to the size of the opening. A large number correlates to a small opening, and a small number to a large opening. The numbers used to represent the size of the opening are called the f-stop. An opening of f/2 means a large opening in the lens, whereas a f/16 means a small opening in the lens. Small number=large opening, large number = small opening. When you hear or read about “stopping down”, what that means is adjusting the diaphragm to a higher number f-stop, and a smaller opening in the lens.
Without going into a physics lesson on the properties of light and how lenses effect the light passing through them, the opening in the lens controls the depth of field, that is the range in distance of things that are in focus to the camera. The larger the opening in the lens, the less distance there will be in focus. The smaller the opening in the lens, the longer the distance there will be in focus.
Here’s some examples to help you. Let’s say you are focused at 10 feet. At an aperture setting of f/2, a very large lens opening, things only a few inches closer to you than 10 feet will be in focus, and things only a few inches farther away than 10 feet from you will be in focus. The focal range is only a few inches either way from 10 feet away from you. If you stop the lens down to f/22, a smaller opening in the lens, everything from 7 feet to 20 feet will be in focus. Now your focal range is from 7 feet to 20 feet, with everything in between in focus.
Here’s a really bad drawing I did in paint to try to help illustrate this. The figure on the left has the camera and is photographing the figure on the right, and is focused on the figure on the right. How much of the rest of the scene is in focus is represented by the distance between the colored vertical lines associated with the f-stop of the same color.
As you can see from the drawing, at f/2, not very much of the scene is in focus. At f/22, a good deal of the scene is in focus.
Small number=large lens opening=short depth of field and very little in focus.
Large number =small lens opening= longer depth of field and more of the scene in focus.
To make it more complicated, lenses perform far better with a smaller opening, that is, a higher f-stop. Again, this is due to the physics of light and lenses.
The farther you stop the lens down, adjust to a higher f-stop, a smaller opening in the lens, the sharper your pictures will be. You may well ask why not just stop the lens down and leave it there? In a perfect world, that’s what we would all do most of the time. It’s the Ansel Adams school of photography. He and some of his friends formed the f/64 club, photographers who used nothing but the highest f-stop possible. The problem comes in that in order to get the proper exposure, you have to leave the shutter open for such a long time that either the camera or the subject moves during the time the shutter is open, resulting in a blurry picture despite the fact that the aperture was set to achieve the best results possible.
Photography is always a trade-off, striking the best possible balance possible. I’ll get to that more after shutter speed, but first one more thing about aperture and depth of field.
There are times when you may want to limit the depth of field that is in focus, to isolate the subject of your photo from the background, foreground, or both. An example would be if you were photographing a wildflower set against a busy background that would take the emphasis off from the flower. Then you would choose a small f-stop, larger lens opening, and shorter depth of field so that only the flower itself was in focus. Or to use the example in my drawing, maybe you want only the person on the right to be in focus, and nothing else, so you would use a larger aperture.
This is the amount of time the shutter in the camera is open to allow light to strike the film or sensor. Think of blinking your eyes in reverse. While we’re awake our eyes are open most of the time, and we blink for a split second every once in a while. The opposite is true in a camera, the shutter is closed most of the time, and when we press the shutter release, the shutter opens for a measured amount of time, then closes again. The time the shutter is open is measured in fractions of a second, like 1/60 sec. That is also considered the longest shutter opening for taking pictures with a handheld camera, 1/60 sec. For exposures longer than that, you have to mount your camera to a tripod or some other way of holding the camera steady while the shutter is open. Generally, the faster the shutter speed, the less amount of time the shutter is open, the better your pictures will be. However, there is no limit to how long the shutter can be open, other than camera movement.
Astronomers use exposure times running into the hours when photographing objects in our solar system and beyond. They use a motorized mount for their telescopes and attached cameras that turn at exactly the same speed as the earth rotates. Even though the camera is moving in relation to the earth, it is stationary in relation to the objects being photographed, and therefore the pictures come out sharp. So shutter speeds can range from hours down to 1/2000 of a second or less, depending on the camera. Where shutter speed is most important is controlling camera movement while the shutter is open, or movement of the subject while the shutter is open. It isn’t only animals that you have to worry about their moving while taking a picture, plants do too if there is enough wind. Especially when you are photographing flowers, or an insect on a small plant stem that is moving in the breeze. But, even on a larger scale, trees blowing in the wind can make a landscape shot look fuzzy if the shutter is open long enough.
The balancing act
OK, we have three ways of controlling the exposure to light when we are taking pictures, the ISO rating, how sensitive the recording media we are using is to light. The aperture, the opening in a lens that controls how much light reaches the media. And, shutter speed, how long we allow light to reach the media we are recording on.
In a perfect world, every time we wanted to take a photo, there would be enough light that we could set the ISO rating to the minimum, stop the lens down to its maximum f-stop (smallest aperture) and still use a shutter speed so fast that camera movement or a moving subject wouldn’t be a problem. We don’t live in a perfect world, so we have to strike a balance between the three. Animals tend to be most active and easiest to photograph in low light situations. We have cloudy, foggy days when you have to use a flash even in early afternoon. Sometimes the lens has to be wide open, and we have to use a fairly slow shutter speed in order to be able to capture any image at all.
The good news is that modern cameras are very good at performing the balancing act on their own. The manufacturers have done an excellent job of programing cameras to capture good shots under some terrible conditions, so I recommend that you set your camera to take advantage of that. Both of my cameras are set to the program, or “P” mode over 90% of the time. Why? Because when you are trying to photograph wildlife, split seconds count.
I still have my first 35mm SLR camera, a Pentax Spotmatic II, a very good camera, but totally manual. I have been able to get some good wildlife shots with it over the years, but I get more good wildlife photos in a month these days than I used to get in a year using the Pentax, all because of speed. With the Pentax, I would have to turn it on, manually focus, manually set the shutter speed, and manually set the aperture while watching a light meter in the viewfinder, and most of the time, what ever animal I was trying to photograph was on its way to safety before I could get everything adjusted for a good photo. With the modern point and shoot settings, that’s what you do. Point the camera at the animal, start pressing the shutter, and when you hear the beep that it is ready, shoot. It takes a fraction of the time. I will say that I have also gotten much better at sneaking up on critters, I’ll cover that later.
I will also cover later on the times when and why you should use some of the other settings your camera probably offers, when you have the time to change those settings, such as shooting landscapes. But for most shots, the program mode works very well, and you should probably leave you camera set to that mode most of the time when you are carrying it.