The Basics of Exposure 4 - Basic Exposure in Practice

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[This is the fourth article in a series on Basics of Exposure. Before reading this one you should have read, or at least have looked at, Basics of Exposure 1 – Overview and Basics of Exposure 2 – Aperture, 3 – Shutter Speed, as these build one on the other.]

In this article we will be putting ISO Setting, Aperture and Shutter Speed into practice in a series of examples of how to use these three to get the right exposure.

Average and Non-Average Scenes, Creative Effects

As long as everything in the scene you are trying to photograph is average, the automatic exposure meter in your camera will take care of the exposure. You can set your camera on fully automatic and let it set the aperture and the shutter speed and in some cameras, the ISO all automatically without you giving it a moment’s thought. You can concentrate on composing the shot carefully and pressing the shutter release and you will be able to see your great pic on the camera’s LCD display.

There are certain decisions you need to make, even when shooting in full automatic mode. One of these is the choice of picture quality. Some more basic cameras only allow you to shoot different size JPEG files (Standard, Fine, Superfine, etc.). Some let you shoot TIFF as well as different quality JPEGs. Yet others give you the option to shoot in RAW mode. While this will be the subject of a full article where we can go into all the details of different file types and sizes and their purposes, for now you should know that if you want to do some processing on the photos you shoot, using Photoshop or other software, while preserving the original photo as a sort of digital negative, you should shoot RAW (if your camera permits it). If you are in the habit of downloading your photos and printing them as-is or posting them on the web as-is then you can save space on your memory card and your hard drive by shooting JPEGs (if the photos mean anything to you at all, you should stick to the higher quality JPEG).

Some cameras, in full automatic mode, will decide even the file format and size for the shot. But the camera manufacturer cannot guess what you intend to do with the photos, so you should read your camera manual and take charge of the file type you will shoot as covered above: RAW (if your camera can), TIFF (if your camera can) and JPEG (high, medium, low quality).

So, key to knowing whether to shoot on automatic or take some control of the camera settings is what we mean by “average.” What I’m calling an average subject is outdoors, daylight, sunny or cloudy but reasonably bright, and if it is sunny then you are shooting with the sun behind or above you, and your subject is not against a very bright or very dark background. That’s average. You can safely put your camera on automatic, point and shoot. The camera will work out the best shutter speed to avoid camera shake and the corresponding aperture. You’l get a good exposure just about every time.

Even top professionals will leave their camera on automatic for many of the photos they take. The difference is that they also know when not to, and they know all the different camera controls at their disposal and when to use which to make the photo come out the way they want it to. A professional thinks in terms of MAKING a photo, not TAKING a photo. Remember that.


The above two photos show average scenes which lend themselves to shooting on full automatic (and they were taken on full automatic). They are average scenes from a lighting and exposure point of view.

By non-average, I am referring to a wealth of photographic situations where it is really not enough to just keep your camera on automatic without being aware of or controlling what is going on in any way.

For example, you’ve seen those photographs where your boyfriend or girlfriend or child is standing on the beach with a bright sky behind and you take a photo and the face is so dark you can hardly recognize your loved one. But the beach and the sky look good! Or the ones where the person is against a dark background and this time their face comes out seriously overexposed, pale and anemic. Photos taken in the snow – dark silhouettes of the guy on the ski board while the background looks OK. Fireworks, night shots, and many other individual situations. Somehow the photos don’t come out the way you had hoped.


This is not an average subject. The light background fooled the camera’s meter into underexposing the photo on the left. A second exposure, compensating, brings out the detail in the fisherman’s face.

Why, you ask yourself, did it not come out the way I saw it? The answer is that no matter how clever the camera manufacturers get, the light meters and computers inside your all-singing-all-dancing digital camera that regulate and determine the exposure for you, cannot THINK! The light meter in your camera basically assumes that you have an average scene in front of you. If you have an average scene it will meter it correctly. If you do not, then the exposure meter will be fooled and you will need to do something about it to make sure your photo comes out the way you want and expect it to.

Not only do these non-average situations require some understanding, there is also the situation of the effect you want to create in the photo, and no camera can predict that. You see a waterfall: do you want every single droplet to be sharp and clear? Or do you want the water to be a soft, flowing mass? Both are valid. It’s your decision. Or the close-up of the flower. Do you want it all in focus and sharp or would you like to have very narrow depth of field so only the pistils are in focus and the rest gradually fades out of focus? It’s a personal preference based on vision, purpose, message and even taste. You can’t expect a camera chip to have vision, purpose, message and taste!


These two photos show different uses of depth of field, the one on the left showing very shallow depth of field whereas the one on the right shows greater depth of field. This is not something the camera can decide for you.

So, all of these reasons above make it worth your while to learn and use the different controls your camera provides and to turn that mode knob off “Full Automatic” and learn to be in charge of how your photos are going to turn out.

Let’s look at some simple examples.

Shutter Priority

You’re at your son’s soccer game on a sunny Sunday afternoon. You don’t want a straight, typical shot of a soccer game. You want to show that there is some motion involved. You think it over. OK, that means I need a slower shutter speed. You look through your 200 mm lens and press the shutter button down half way and it says f/5.6 at 1/250^th of a second. The ISO is at 100. Well, fast though your son may be, that shutter speed is not going to show him in motion. It will show him stock still. Not what you want. You want to follow his motion at maybe 1/15^th or 1/30^th of a second. OK. Well the camera doesn’t know what you want to do. So, take it off automatic and here is a good instance of using Shutter Priority mode. If you don’t know how to set your camera on Shutter Priority (Tv) read your manual! You should read your manual several times so you learn how to really use all the features of your camera. Otherwise you’re wasting them all. And they don’t come cheap.

OK. Switch the camera to Shutter priority and set the shutter speed at 1/30^th of a second. Your aperture will change automatically, probably to f/16 or so. That’s fine. You’re not looking for shallow depth of field. Your son is just then tearing down the field dribbling the ball and dodging this one and that one. You get him in your viewfinder, follow his progress, look for the perfect moment and press the shutter button (remember to follow through). Look at the shot. Is there enough motion in it? If not, try changing the speed to 1/15^th and take another one. This one is perfect. It’s blurred enough to show the motion but your son is still recognizable. Great shot. You would never have gotten that on full automatic unless by sheer luck.

A slow shutter speed helps show action in this photo. This is not something the camera can create automatically, except by accident. You need to take control.

Aperture Priority

There are times when the aperture is more important than shutter speed. Let’s say you are taking a scenic shot. There are some beautiful orange California poppies almost immediately in front of where you’re standing. Then some fields and a river and, in the distance, snow-capped mountains. It’s fairly late evening and the light is a bit low. You want maximum depth of field. If you shoot on full automatic, the camera is going to suggest a wide aperture so that you have a fast enough shutter speed to prevent camera shake. Perhaps it sets the camera at f/4 at 1/125^th of a second, ISO 100. You don’t want to raise the ISO because you don’t want a grainy photo. But you need a much narrower aperture in order to get the depth of field you need, maybe f/16 or even f/22.

What’s the answer? Well, the first thing you need to do is put your camera on aperture priority and set the aperture to f/16. This will give you a shutter speed of 1/8^th of a second. You can’t hand hold a camera at 1/8^th of a second and have a really sharp photo, I don’t care how steady your hand. So you put the camera on a tripod and go ahead and shoot at f/16 at 1/8^th of a second. Look at the result. Should be perfect.


These two photos show another use of depth of field. The one on the left shows maximum depth of field and the one on the right more limited depth of field.

Exposure compensation

You can exert control over the image while still shooting on automatic. Your camera, unless it is extremely basic, offers exposure compensation. What this means is that you are overriding the exposure values (aperture and/or shutter speed) determined by the camera’s light metering system.

Some cameras have a knob that you turn one way or the other after you have pressed the shutter button down half way (which focuses the camera and sets the exposure). On others you go to the menus and compensate up or down for the exposure depending on your lighting conditions. Again, READ YOUR MANUAL. It will tell you how to compensate exposure by various increments (usually 1/3^rd of an F-Stop or half an F-stop at a time, up or down). With a bit of experience you can look at a scene and estimate whether it needs more or less exposure than your camera reckons.

But you can learn by taking a photo, looking at the result on your LCD screen and notice whether the result is correct or over- or under-exposed. Then, if it is over- or under-exposed, you can compensate and, hopefully, take the photo again. If it’s too dark or the main subject of your photo is too dark, it is under-exposed, so you need to compensate by increasing the exposure, say + 1/2 an F-stop or + 1 F-stop and try again. If it’s too light, you go – 1/2 stop or – 1 stop. What does this mean? Well, let’s say the exposure was f/11 at 1/125^th of a second. This is what the camera thought was the correct exposure. But you look at the result and your friend’s face is too dark. So you compensate by + 1 stop. The camera will reset the exposure to f/8 at 1/125^th of a second or f/11 at 1/60^th of second (either of these will give you the same exposure). You take another photo at the new, compensated exposure and have a look at the result. Now you’re happy with it or you are not. If not, you compensate further, up or down as needed.

But after you’ve seen a few of these, you will recognize the situation when you run into it and compensate before you take the photo. You are taking a photo of your boyfriend, a close-up of his face with the bright sky behind. You know that the bright background is going to fool the camera’s light meter and the face is going to come out way too dark. So before you take the photo you compensate by + 1 stop and shoot. Perfect. Or, if it’s still a bit dark, you can compensate more after you look at the result of the first shot.


Three shots taken very close to each other in time. The first one is the result of the camera’s automatic exposure, the second one shows 1 stop more exposure using the exposure compensation control. The third one is 2 stops more exposure than the first. Which do you like? This is definitely NOT an average subject.

Night shot

OK, here is another one. You are on vacation in Paris (or Rome, London or New York or anywhere really) and walking the city streets at night. There’s a beautiful view of Notre Dame cathedral or a Baton Mouche river boat. If you just point your camera at it on automatic and shoot, it’s going to try to make the scene look like an average scene. It will assume you want the shot to look like it was shot in bright sunlight. You want the photo to look like it’s night time, dark with bright lights and enough detail to see a little of the scene but you don’t want it to look like broad daylight!

How do you handle this? Some cameras, particularly of the point-and-shoot variety, give you a range of settings to cope with different situations and this is a possible solution. You set it on a night shot setting and it will automatically set the ISO to a higher setting (400? 800?), compensate by – 1 or 2 stops, and maybe give you a good result. But it would be worth knowing what to do. You want to underexpose the photograph by one or two stops (you can experiment) so that it looks like it’s taken at night. You may want to go to a higher ISO setting but don’t go too high unless you want that grainy look. Maybe 400 or 500 should be enough. Then underexpose your shot using your exposure compensation control. Underexpose by 2 full stops and take your photo. See how it looks. You can adjust the compensation to get the look you want.If you just leave your camera on automatic with no changes, you are likely to get a pale, washed out looking photo as the light meter in the camera struggles to turn your night scene into an average, brightly lit daylight shot.

Two photos taken within minutes of each other of the New York skyline. The top one was taken with the camera set on automatic (you can see it tries to make it into an average, daylight shot).. The lower one was given two stops less exposure by use of the exposure compensation control.

Well, here are just a smattering of examples of where you need to assert your new-found knowledge and skill, your superiority over mechanical devices and computers and override the automation in your camera in order to get the result you want. There are many, many more. As you get into it and start getting used to using these various controls, you will expand from there.

The test is not whether you use your camera on manual or use all the controls or not. The test is whether or not you are MAKING the photos you want, looking the way you want them to look and not losing any (or losing very few and no important ones).

So, read your camera’s manual, figure out exposure compensation, shutter priority, aperture priority, ISO setting and get going. We’ll go into full manual mode and more on these other controls in future articles.

David © Phillips is a professional writer and photographer living in Seattle, WA. You can find out more about him and his work at www.dcpcom.com.