Get the Most From Your Digital SLR

Transcription

1 Get the Most From Your Digital SLR Lesson Two: Getting Photos Correctly Exposed Table of Contents Introduction... 1 Definitions... 2 A Crack In The Door... 2 Exposure... 3 Digital SLR Light Meters... 4 Metering Scale... 4 Numerical Metering... 4 Graphical Metering... 5 Dynamic Range... 6 Middle Gray - Or, How to Confuse an SLR Meter... 7 Exposure Compensation... 9 Balancing Aperture and Shutter Speed (Manual Exposure) Preventing Blur Subject Motion Blur Camera Motion Blur Which Comes First: Aperture or Shutter Speed? Exposure Examples Conclusion Exercises Introduction In the first lesson, you learned about aperture and shutter speed. Hopefully those two concepts are pretty clear now. If not, here's a quick refresher on aperture: Aperture indicates how wide your lens is open and how much light it lets in Aperture is measured in f-stops Small f number = Wide aperture Large f number = Narrow aperture Aperture also controls depth of field Wide aperture = Shallow depth of field Narrow aperture = Wide depth of field And now, a quick review of shutter speed: Shutter speed lets you control how long the shutter stays open and how much light hits the camera's sensor Shutter speeds are measured in seconds and fractions of seconds A shutter speed of 1/250th of a second appears as 250, while 20 seconds appears as 20" Changing shutter speed allows you to freeze and blur motion Fast shutter speed = Motion stopped Slow shutter speed = Motion blur Page 1 of 23

2 While fiddling around with aperture and shutter speed you may have noticed that there are actually four modes on your digital SLR control dial in addition to the AUTO and scene modes. These modes are Program (P), Shutter Priority (S or Tv), Aperture Priority (A or Av) and Manual (M). Program mode is very similar to auto mode, except that you have the ability to adjust certain camera settings like ISO, white balance and metering (more on these in later lessons). The important point is that in program mode the camera is selecting BOTH an aperture and a shutter speed for each photo you take. In shutter priority mode, you control the shutter speed, and the camera picks a matching aperture to get a good exposure. In aperture priority mode, you control the aperture, and the camera picks a matching shutter speed to get a good exposure. So what's manual mode good for? Glad you asked. That's going to lead us right into this lesson. Definitions Warm up those brain cells. It's time for this week's definitions. I will talk about these camera terms as plainly as I can, but remember that some of these concepts are hard to "get" in just one sitting. You have to read this, play around with your camera a bit, and then come back to it. Eventually you'll have that AHA! moment and after that everything will fall into place. A Crack In The Door Aperture controls the amount of light that enters the camera. So does shutter speed. Seems like there might be a relationship here. There is. Imagine that you're inside a building at night. You're standing in a hallway that's lit, and you'd like to find out what's behind door number one. The light is off in the room behind the door, so you'll have to see into it using light from the hallway. You have two alternatives: 1. Crack the door and hold it open for a long time until your eyes adjust to the dim light in the room 2. Pull the door wide open for a short period of time to let all the light from the hallway fall into the room Either way, you are letting the same amount of light into the room. Narrow opening + Long time = Wide opening + Short time Page 2 of 23

3 You might see where I am going with this. Aperture represents how wide the door opens and shutter speed is how long it stays open. This means that there are always two ways for you to take the exact same photo. Before I get into that, let's talk about exposure. Exposure 9 times out of 10 you want your photo to be correctly exposed. Let's go back to our door in the hallway. If you open the door wide enough and long enough, you'll just let in enough light to the room to see it clearly. In this case, the room is correctly exposed. If you don't open the door wide enough or long enough, the room is too dark - it's under-exposed. If you leave the door open too long you let in too much light and over-expose the room. You've no doubt seen over-exposed and under-exposed photos before but it may not be clear which was which. Under Exposure Under-exposed photos look like they are behind a thin veil of black silk: colors are muted, shadows are very dark, and the entire photo looks drab. Over Exposure Over-exposed photos look like a scene from a sci-fi movie when the alien ships are landing: everything is washed out in bright light, and all texture and color is lost. Page 3 of 23

4 Correct Exposure A correctly exposed photo looks the same way (or pretty much) as it did when you were looking at the scene with your eyes. Colors are natural, shadows aren't pure black, and there is plenty of detail in the entire photo. In AUTO, Program, Aperture Priority and Shutter Priority modes, your camera is always trying to capture photos like the last one in this set, where the exposure is balanced. But there will come a time in your photographic journeys when you're going to have to "tweak" the exposure settings. You can adjust exposure settings either to create a dramatic effect, or to compensate for challenging light that can trick your camera into making a bad exposure. So how do you get used to adjusting the exposure settings on your own? The first step is learning how to read your digital SLR's light meter. Digital SLR Light Meters Every digital SLR camera includes a light meter: a device that detects the amount of light entering the camera. Your light meter evaluates your aperture and shutter speed settings, and then it determines if your photo will be over, under, or correctly exposed. The meter shows you how your photo is going to turn out using either a numerical or graphical display that appears in the camera's viewfinder (and also sometimes on the LCD display). Metering Scale In lesson one, you learned that apertures are measured using f-stops. You also learned that the aperture scale can be divided into halves or thirds. Your light meter uses a similar scale to tell you HOW MUCH a photo is going to be over or under exposed. In the case of your light meter, the scale doesn't represent f-stops, but instead is showing you something called stops of light. Numerical Metering I'll start by talking about numerical metering, because it's a bit easier to grasp than the graphical metering display. The number zero indicates that a photo is correctly exposed Numbers greater than zero indicate over exposure Numbers less than zero indicate under exposure Page 4 of 23

5 The scale that you have your camera set to (half vs. thirds) will determine the metering numbers that the camera displays. Some examples: Zero the photo will be correctly exposed the photo will be over exposed by 1/3 of a stop the photo will be under exposed by a half stop the photo will be over exposed by two full stops the photo will be under exposed by one and 2/3 stops The farther you get away from zero, the more severely over or under exposed your photo is going to be. While you might not be able to immediately identify a photo that's been under exposed by a half stop, an image that's under exposed by two stops should be painfully obvious (and WAY too dark). Graphical Metering While some digital SLRs only display numbers for light metering, the vast majority display a graphical metering display. Instead of numbers, a graphical display displays values from minus to plus two, with zero right in the center of the scale. A small arrow (or other form of indicator) points to the metering scale to show you if your photo is over, under, or correctly exposed. When the arrow is centered on the scale (pointing to zero) this indicates a correct exposure (according to the light meter). Let's take a look at some examples. Correct Exposure This graphic shows you that the scene is correctly exposed. The arrow points to the center of the graph, which is equivalent to the zero point (neither under nor over exposed). Over Exposure In this case, your photograph will be over exposed by 2/3. You can see that the indicator is pointing to the 2/3 marker. Page 5 of 23

6 Under Exposure This metering scale shows you that your photo will be under exposed by one full stop of light. The indicator is pointing straight at minus one on the scale. There are two important things to note about these examples: 1. This shows a metering scale that is divided into thirds, allowing for a finer level of exposure control. If your camera is set to half stop increments, there will only be one sub-division in between each full stop marker. 2. The examples show a scale with minus on the left and plus on the right. While common amongst many SLRs, all Nikon digital SLRs display this scale REVERSED: with minus on the right and plus on the left. Congrats - now you know how to read a light meter. But how can you leverage this newfound skill? More importantly - when the camera is set to AUTO, Program, Aperture Priority and Shutter Priority mode, it's making exposure judgements AUTOMATICALLY. In fact, in all of these modes, you don't have to pay ANY attention at all to the metering scale (it will always be set to zero). So why not let the camera change settings to get correct exposures for every photo? Why would you even want to fiddle around with the metering scale? Here's the problem: even though your digital SLR is incredibly sophisticated, it can't judge exposure correctly 100% of the time - but you can. Dynamic Range Your eyes have incredible dynamic range. If you are standing on a forest path in deep shade and there are streamers of bright sunlight breaking through the trees, you can see everything. You can make out the veins on the leaves in direct sunlight, and at the same time you can see the pattern of the tree bark that's in the shade. Unfortunately, your digital SLR camera can't capture what your eyes see. Let's take our example from a forest path out to the beach at sunset. When you take a photo of the sun setting there is a huge amount of contrast in between the setting sun itself (a bright source of light) and any part of the landscape that has fallen into shadow. Faced with this contrast, your camera will do one of two things: Page 6 of 23

7 Expose for Highlights When the bright sun is correctly exposed, the landscape that is not fully lit appears almost black in your photos. The extreme contrast variation between the bright sun and the dark land prevents the camera from exposing both correctly at the same time. That sunset sure looks pretty, but the composition leaves a lot to be desired since you can't see any detail in the foreground. Expose for Shadows The alternative isn't too much better - now the land is correctly exposed (you can see detail again) but the primary subject - that beautiful sunset - is terribly over-exposed. It's so over-exposed that you can't even tell that it's a sunset anymore. Sure, the plant, rocks and waves turned out nice, but that's not exactly the focal point of this particular photo - it loses a lot without that sunset behind it. This is why many photographic opportunities that look exceptional when viewed with your eyes don't turn out that well when you take a photo. The problem is compounded when you leave your camera on AUTO mode. Faced with extreme contrast, the camera is making a choice for you - whether to expose for highlights or shadows. The real kicker is that if you take the same photo TWICE in AUTO mode, you might get two very different photos. Extreme contrast is one problem - but there are also many other times when your light meter isn't going to judge exposure correctly. Middle Gray - Or, How to Confuse an SLR Meter Under standard daylight conditions, your camera's meter is going to do a pretty good job of judging exposure. When the meter is set to the zero point, you can trust that the exposure is not over or under exposed. While this is true in daylight, it is not true under a variety of other lighting conditions. Why is this? Page 7 of 23

8 Put simply, your digital SLR camera is a generalist. The light meter inside the camera has been designed to judge exposure for MILLIONS of possible lighting situations. It does this by trying to expose every subject evenly, regardless of brightness or color. This even exposure setting has a name: it's called middle gray. Here's how it works: let's say that you're taking a photo that includes a lot of white. Your camera wants to tone down that white so that it doesn't over expose. Unfortunately, it usually takes it too far, and what should appear white will turn out gray in your photo. Now let's go to the opposite extreme - a scene that includes a lot of dark tones. In this case the camera will want to brighten everything, and all of those nice dark tones will wind up looking - you guessed it - gray. Middle gray is most apparent in photos taken during the Winter - specifically, any photo of snow. Let's say that you have your camera in Aperture Priority mode because you want to control your depth of field. You compose your photograph and check the light meter to see what it's telling you. The light meter is set right at the zero point - a correctly exposed photograph. You take the shot, and here's what you wind up with: Take a good close look at that snow - does it look white to you? But your light meter told you that the photo was correctly exposed - it has, in essence, lied to you. Since the camera wants to expose everything as middle gray, it thinks that the image IS correctly exposed when the truth is that it's under exposed. Page 8 of 23

9 Your camera will under expose any time there is a lot of white or light tones in the scene including: snow, fog and sand. A more subtle problem is that many digital SLR cameras under expose in shade, regardless of the tone of your subject. Again, the meter is shooting for middle gray and tends to get off when the available light is overcast. While an overcast day can provide you with nice even lighting for your subjects, you have to be careful that the camera isn't under-exposing every single shot that you take. This brings us to the BIG QUESTION: if your camera's meter is going to fib, and using the camera modes where it determines the exposure settings aren't always going to yield correctly exposed photos, what's a self-respecting photographer to do? I'm glad you asked. Exposure Compensation The simplest way to exert some measure of control over your camera is to use the exposure compensation setting. Exposure compensation is a fairly simple way of altering how your camera captures photos without going all the way to manual mode (which I'll discuss in the next section). Let's head back into the snow. You now know that in snowy conditions your digital SLR light meter is going to get a bit confused. It's going to detect that there's a lot of bright white in the photo and in an effort to capture middle gray it will under expose every single photo you take when you're using one of the auto exposure modes. But here's the thing: in Program (P), Aperture Priority (A or Av) and Shutter Priority (S or Tv) modes, you can FORCE the camera to either over expose or under expose every shot it takes. You do this by using the exposure compensation setting on your camera and adjusting it accordingly. In the case of snow, you'll want to set it to over expose by about one full stop of light. Here's how this works: 1. Set your camera to Program, Aperture Priority or Shutter Priority mode 2. Press down halfway on the shutter release button to activate the light meter 3. Set the exposure compensation so that the meter is permanently set to +1 Even though the camera THINKS that it's over exposing every photo, you know better. You're forcing the camera away from middle gray so that white snow actually turns out white. You can also use exposure compensation for many of the other situations where the camera's meter will under expose: in fog, at the beach and in the shade. Are there times when you intentionally want to under-expose? You bet. Page 9 of 23

10 You'll have to set your exposure compensation to a negative number in instances where the scene that you're photographing is predominantly dark or even black so that the black colors don't turn out gray. I've also found it useful to set a negative exposure compensation if you're taking photos where there's a lot of bright sunlight punctuated with large areas of shade. Here's why: even if you under-expose every photo you take under these conditions, you can fix it later with an image editing program. It's quite easy to enhance shadows and bring out detail that may not be visible in the original image. However, if you over expose a portion of your image, the detail in that area is forever LOST. There is no way that you can edit the photo later to return detail to a surface that's too bright. In cases like this I opt for "better safe than sorry" and dial down the exposure compensation so that the meter is under exposing all of my photos. If you change your exposure compensation setting MAKE SURE you set it back to zero after you're done taking photos. The reason for this is simple: it's quite easy to forget that you've adjusted the exposure compensation setting. Once set, exposure compensation does not default back to zero when you turn the camera off. It's quite easy to snap a large number of photos before you realize that the exposure compensation is set to over or under expose. Balancing Aperture and Shutter Speed (Manual Exposure) Now that I've shown you the easy way to over-ride your camera's light meter to get photos that are correctly exposed, I'm going to introduce you to manual exposures. This should not be too intimidating at this point. After all, you have all the building blocks that you need for this to make sense: You know how to read your camera's light meter and you can tell when it thinks the exposure settings are correct (the zero point) You know how to change aperture and that changing it affects depth of field You know how to change shutter speed and that changing it affects how the camera captures motion Why use manual control? There are several benefits to doing so: You can adjust exposure settings for individual photos (whereas exposure compensation changes the settings for EVERY photo you take) You can intentionally over or under expose your photos for dramatic effect, which results in more dynamic images YOU are making the decisions about the aperture and shutter speed settings, NOT the camera - and your aesthetic sense will ALWAYS be better Page 10 of 23

11 So, take a deep breath - and let's get to it. You are out in your backyard one fine day and you want to take a photo of a flower. It's a bright sunny day, so you're going to be able to use a wide range of aperture and shutter speed settings. Here are the steps that you take to set the exposure manually: 1. Set your camera to manual mode (M) 2. Use the control dial on your camera to select an aperture of f/8 3. Point the camera at the flower, and press down halfway on the shutter release button 4. The light meter will activate - take a look at it to see if your photo is over, under or correctly exposed 5. Without changing the aperture, change the shutter speed until the meter hits the zero point 6. Press down all the way on the shutter release to take the photo For the purpose of this example, we're going to trust that the light meter is telling the truth and that the photo will turn out correctly exposed. Photo #1 - Balanced Exposure Aperture: f/8 Shutter Speed: 1/250 Please note that the shutter speed you wind up with for a correct exposure may be different. It depends a lot on how much available light there is. But in sunny conditions, f/8 and 1/250 is going to be close for a subject without a huge amount of contrast. Now you're going to intentionally over-expose by one full stop of light. In the charts below I've highlighted the aperture and shutter speed settings used for this first photo (aperture is on top): We're going to leave shutter speed alone for the moment, and we're just going to change one variable: aperture Since we want to over expose by one full stop of light, we're going to change the aperture from f/8 to f/5.6 - making it wider and letting in twice as much light. Page 11 of 23

12 Photo #2 Over Exposed Aperture: f/5.6 Shutter Speed: 1/250 And here's the aperture and shutter speed scales with the new setting: Getting the hang of this? Now let's balance our exposure again. Since we've opened the aperture wider (letting in more light) we must compensate by making the shutter speed faster (letting in less light). Here's the relationship: WIDER APERTURE --> FASTER SHUTTER SPEED Since the aperture is now f/5.6, we need to go up to the next full shutter speed setting (we're dealing with whole stops for now, not halves or thirds). That shutter speed is 1/500th of a second. Photo #3 Balanced Exposure Aperture: f/5.6 Shutter Speed: 1/500 Voila! We're back once again to a balanced exposure. And what's the net result? We've opened up the aperture by one full stop which has reduced the depth of field. Now let's head in the opposite direction. Instead of less depth of field, let's get more. First, go back to your starting point: f/8 and 1/250: Page 12 of 23

13 Photo #1 - Balanced Exposure Aperture: f/8 Shutter Speed: 1/250 Next, change the aperture to f/11, which narrows the opening and lets in less light. Result? A photo that is under exposed by one full stop of light. Photo #2 Under Exposed Aperture: f/11 Shutter Speed: 1/250 Now, let's compensate. We made the aperture narrower (letting in less light) so the shutter speed must become slower (letting in more light). NARROWER APERTURE --> SLOWER SHUTTER SPEED Slow the shutter speed down to 1/125th of a second to get back to your balanced exposure. Photo #3 Balanced Exposure Aperture: f/11 Shutter Speed: 1/125 And what have we got now? It's a correctly exposed photo with greater depth of field than the first shot you took. Let's take one more look at the aperture and shutter speed settings we used so that you can see all of them side by side: Page 13 of 23

14 APERTURE SHUTTER SPEED METER READING RESULT f/8 1/250 Zero Balanced exposure f/5.6 1/ One stop over exposed f/5.6 1/500 Zero Balanced exposure f/11 1/250-1 One stop under exposed f/11 1/125 Zero Balanced exposure Perhaps it's clear to you now why I titled this section Balancing Aperture and Shutter Speed. Think of it like a scale: put aperture on one side and shutter speed on the other: As the aperture number gets smaller (wider aperture) the shutter speed must get bigger (faster speed) As the aperture number gets bigger (smaller aperture) the shutter speed must get smaller (slower speed) Aperture and shutter speed seesaw all over the place, but in the end they should balance each other out - and THAT is when you've got a correct exposure. Preventing Blur Now that you understand how to manually set both aperture and shutter speed to capture a correctly exposed photo, let's talk about one of the most common problems that you're trying to overcome every time you take a photo. The problem is blur, and it's a result of using slow shutter speeds. There are actually two types of blur that you need to be aware of: 1. Subject motion blur 2. Camera motion blur Let's talk more about each type of blur, and what you can do to prevent it. Subject Motion Blur The only thing that will get you clear photos of fast-moving subjects is super fast shutter speeds. In this case, image stabilization (whether built into the camera or lens) won't help one bit - it only helps to reduce camera motion blur. With that in mind, let's take a look at the following table, which gives you some approximate shutter speeds based on the speed of your subject: SUBJECT SHUTTER SPEED Race cars, jet airplanes, ski jumps 1/2000-1/4000 Running children, dogs, bicycles, trains, sports 1/1000-1/2000 Page 14 of 23

15 Children at play, wildlife 1/500-1/1000 Trees on a windy day 1/250-1/500 As your subject matter slows down, you can get away with slower shutter speeds - you're not trying to freeze something moving really fast. But if your passion in life is photographing hummingbirds, then you're constant goal will be to achieve the fastest shutter speed you can given the amount of available light. Remember, there's a limit here: the maximum aperture of your lens. As your shutter speeds get faster and faster, your aperture must open wider and wider to let in enough light for a balanced exposure. But at some point you're going to realize that your lens can't open any further. Let's say that you're photographing a sporting event on a really overcast day. You know from the table above that in order to get sharp photos you need to be using shutter speeds around 1/1000 to 1/2000. You set your camera to shutter priority mode and adjust the shutter speed as fast as it will go. If you've got a lens with a maximum aperture of f/5.6, then you might find that the fastest shutter speed you can use is 1/250. You're pretty much stuck, and have to make the best of the limited shutter speed that you have to work with (unless you leverage ISO, which I'll talk about in the next lesson). If you've ever wondered why there are such expensive lenses out there, this is your answer. As the maximum aperture on the lens gets wider, the lens goes up in price. But these expensive lenses with wide maximum apertures let you use faster shutter speeds when there's less available light. To sum up: In order to photograph fast action, you must use fast shutter speeds The top shutter speed you can use will depend on the maximum aperture of the lens and the amount of available light Camera Motion Blur While image stabilization (IS) is becoming much more common in modern digital SLR cameras, it's still not a universal feature. Since that's the case, I'll begin the discussion of camera motion blur for those of you without IS. To review, here's that photography rule of thumb from lesson one: If you're holding the camera in your hands and not using a flash, don't use a shutter speed slower than 1 over the focal length of the lens. Page 15 of 23

16 Simply put, if you're using a 50mm lens, choose a shutter speed of 1/60th of a second to ensure that there won't be any blur in your photo due to camera shake. If you take a lot of photos indoors without flash, you're going to be constantly pushing this boundary. It has to do - again - with the maximum aperture of your lens: let's say that you're taking photos in your living room and your lens has a maximum aperture of f/3.5. In aperture priority mode, you select f/3.5, but find that the matching shutter speed is 1/30th of a second. Now the issue is the focal length of your lens. If you're using a lens with a focal length between 40mm and 50mm, your photo might look blurry because of camera shake (although sometimes you can pull this off if you hold the camera VERY steady). The sure thing: use a focal length that is smaller than 30mm to ensure that all your photos turn out nice and clear. Now let's talk about what happens when we throw IS into the mix. With IS activated you CAN use shutter speeds slower than the focal length of your lens, typically up to three stops slower. Here's the shutter speed scale again: Let's say that you're using a 50mm lens. The shutter speed that you need without IS appears in bold and with IS is bold and red: There is a three stop difference between 1/60th of a second and 1/8th of a second. This is the great thing about image stabilization: you can hold a camera in your hands and take photos at 1/8th of a second that still turn out sharp and clear. Without IS, a hand-held photo at 1/8th of a second would be a blurry mess. But remember: this only works with a non-moving subject. If your subject is leaping all over the place and you use a shutter speed of 1/8th of a second with IS activated, the BACKGROUND will appear nice and clear, but your subject will be a great big blur in your photo. Which Comes First: Aperture or Shutter Speed? For every shot you take, you've got two main variables to play with: aperture and shutter speed. 1. Shutter speed is the key player when it comes to preventing subject and camera blur 2. Apertures have limits on how wide they can open, and this has a direct impact on your maximum shutter speed Page 16 of 23

17 An inevitable question results: which one should be set first in manual mode? The answer depends on three factors: 1. The amount of subject motion 2. The amount of available light 3. The amount of camera stabilization You might be thinking that since shutter speed is so important in preventing blur, it's the feature that you should always set first when using manual mode. That's not exactly true, and I'll explain why in the table and the examples that follow. SUBJECT AVAILABLE LIGHT SET FIRST RATIONALE Not moving Bright Aperture Since your subject isn't in motion, you don't need to use a terribly fast shutter speed. There is also plenty of light, so you don't have to worry about shutter speed being lower than the focal length of your lens. Set aperture first to control your depth of field, then set a shutter speed to balance the exposure. Moderate Shutter Speed In moderate light, you'll have to make sure that your shutter speed doesn't fall below the focal length of your lens (unless you have IS). In this case, it's best to set shutter speed first so that you can be sure it's fast enough, then select a matching aperture. Dim Aperture In low light, you're going to have to open the lens up as wide as it will go. You could set shutter speed first, but you might find that you'd selected a speed that was incompatible with the maximim aperture of your lens. In low light, it's much easier to set your aperture to its maximum, and then set a corresponding shutter speed. If the shutter speed is STILL lower than the focal length of your lens even with the aperture open all the way, you'll have to brace the camera so that it doesn't shake when you take the photo. Those with IS systems have more leeway to use slow shutter speeds without bracing the camera. In motion Bright Shutter Speed When your subject is in motion, throw your IS out the door and just pay attention to shutter speed. Use the subject speed table provided above to determine how fast to set your shutter speed. With plenty of available light, you should be able to choose from a variety of matching apertures. Moderate Shutter Speed Since the subject is in motion, you're still going to want to set the fastest shutter speed you can to freeze the action. Bear in mind that you might run up against the maximum aperture of your lens, and may have to reduce your shutter speed accordingly to get a correct exposure. Dim Aperture Low light action photography is a lot like low light static photography - you need to achieve the fastest shutter speed you can with the amount of available light. Since it's guaranteed that you'll hit the maximum aperture of your lens, it's much easier to set that first (as wide open as it will go), and then find out the fastest shutter speed you can use. While you can use these guidelines to help you get started, you'll quickly find that you have a preferred method of taking photos. For example, I tend to always keep my camera in aperture priority mode. If I know that I'm taking some fast action shots, I open up the aperture as wide as it will go (the wider opening means I can use a faster shutter speed). Page 17 of 23

18 If I'm taking a portrait or landscape photo, I narrow down the aperture to increase my depth of field, but I do keep an eye on the shutter speed. If it drops below a threshold where either my subject or entire photo will turn out blurry, I simply open the aperture up until the shutter speed is fast enough to prevent blur. That's just my approach - it's also perfectly valid to always set your shutter speed according to the amount of subject and/or camera motion and just let aperture fall where it may. The most important step for you to take right now is to switch your camera out of AUTO mode, and start using aperture priority, shutter priority and manual mode. Once you've developed some familiarity with how each one works, you'll find one that appeals to you more than the others, and that's what you can use in the future. Exposure Examples Let's take a look at some examples to help all of this theory sink in. For each image I'll not only tell you the aperture and shutter speed that were used, I'll also explain the rationale behind which setting I chose first and what - if any - limitations exist. Aperture: f/5 Shutter Speed: 1/2000 Approach: for this image of my dog romping in the water, I knew that I would have to use a fast shutter speed to freeze the motion and get a nice clear shot. It was a bright sunny day so I wasn't worried about the maximum aperture of my lens. I set the shutter speed to 1/2000 first, then selected a matching aperture. Aperture: f/5.6 Shutter Speed: 1/640 Approach: here's another photo of my lab, but this time he's running around in the shade. I knew that I couldn't use a shutter speed of 1/2000 and that I'd run up against the maximum aperture of the lens. I opened the aperture as wide as I could, which provided me with a relatively fast shutter speed given the amount of available light. Page 18 of 23

19 Aperture: f/5.6 Shutter Speed: 1/400 Approach: unlike my dog, this flower wasn't going anywhere. It was in the shade, but there was no breeze and it was perfectly stable. I wanted to blur out the background with a shallow depth of field, so I chose a wide aperture first, then selected the matching shutter speed. Aperture: f/14 Shutter Speed: 1/8 Approach: for this photo I wanted to use a slow shutter speed to blur the water, but I was holding the camera in my hands. I activated the IS system so that camera shake would not blur the ENTIRE image, then I selected a nice slow shutter speed in shutter priority mode. Aperture: f/4 Shutter Speed: 1/400 Approach: with plenty of sun and a non-moving subject, I didn't have to worry about shutter speed being too slow. It was more important to get a shallow depth of field so that the main subject stood out from the background. I set the camera to aperture priority mode, and selected a nice open aperture. Page 19 of 23

20 Aperture: f/2.8 Shutter Speed: 1/1000 Approach: hummingbirds are a prime example of a subject that won't stay still. This photo was taken in partial shade, and I knew that I would have to squeeze the fastest shutter speed I could get out of the camera given the amount of available light. Solution: I set the lens to its maximum aperture and hoped that the shutter speed would be fast enough to capture the shot. If I was taking the photo in direct sunlight (where there was no concern about maximum aperture) I would have set a fast shutter speed first (to capture the subject motion), and then followed up with aperture. Aperture: f/2.8 Shutter Speed: 1/60 Approach: here's another example of leveraging maximum aperture, but with a very different subject in very different light. In this case, the subject isn't moving, but the only available light is coming through a window to the right. I needed to use a shutter speed that was fast enough to prevent camera blur. By setting the lens to the max aperture of f/2.8 I was able to get a shutter speed of 1/60th of a second, which is OK for my non-moving subject. Had the subject been in motion, 1/60th would not have been fast enough to prevent subject blur. Aperture: f/8 Shutter Speed: 1/100 Approach: it may not seem like there's a lot of light to work with here, but there is. Shooting straight at the sun gives you plenty of manual setting options. I was holding the camera in my hands, without an IS system. With a 28mm lens I set the shutter speed to 1/100. I could have gotten away with 1/30 but that would have been pushing the boundary of camera blur. Aperture: f/3.2 Shutter Speed: 1/250 Approach: fireworks can be challenging when it comes to exposure - but even though it's dark out, you don't have to use really slow shutter speeds. The fireworks put out enough light that you can use shutter speeds that are fast enough to capture the action. You can't trust your meter at all under these conditions, and just have to keep checking the LCD to see if you're getting the exposure right. Page 20 of 23

21 Aperture: f/6.7 Shutter Speed: 15 sec Approach: at night you must use a tripod to prevent camera blur - the shutter speeds you have to use are too slow to be balanced by an IS system. Once the camera is completely stable, you can actually use ANY aperture you want, then just select a matching slow shutter speed to get the exposure right. Conclusion We've just covered a HUGE amount of material here, so I thought that it would be a good idea to go back and highlight some of the key points before you tackle the next lesson. Your digital SLR has several modes, and the one that you select will determine whether you control aperture, shutter speed, both or neither. MODE YOU SELECT CAMERA SELECTS Aperture Shutter Speed Aperture Shutter Speed Program X X Aperture Priority X X Shutter Priority X X Manual X X In the automatic modes (Program, Aperture Priority, Shutter Priority), the camera is always trying to get a balanced exposure (where the meter reading is zero). If you want to intentionally over or under expose in these modes you must use the exposure compensation setting. Remember that the exposure compensation is applied to every photo that you take, until you reset it to zero (which sometimes doesn't happen even when you turn the camera off). There are a wide variety of lighting conditions and subject matter that will throw off your digital SLR light meter. Your meter is always aiming for middle gray, so it will make bright white and black look more like gray unless you take control and intentionally over or under expose. Under normal lighting conditions with a subject that is neither bright white nor black, when the meter is set to zero the photo should be correctly exposed. Your SLR's light meter either displays numbers (in the range between -2 and +2) or it shows you a small graphic with a pointer to indicate whether your photo is over, under, or correctly exposed. When using manual mode, you can intentionally over or under expose each individual photo you take. Page 21 of 23

22 A correct exposure is always a balance in between aperture and shutter speed: a change to one of these will necessitate a change to the other in order to keep the exposure balanced. Exercises EXERCISE 1 - METERING This exercise is pretty simple, and it's something you can do anytime, anywhere. Take your digital SLR camera and set it to manual mode. Set the aperture to any number you like. An aperture of f/8.0 is right in the middle of the scale, and a good starting point if you want to use it. Point your camera at any nearby object, and press down halfway on the shutter release button. In the viewfinder you should see the metering scale with the -2, -1, 0, +1 and +2. You should also see a small arrow at the top of the scale showing you whether the photo is overexposed, under-exposed or just right. Without changing the aperture, adjust the shutter speed. You should see the arrow moving back and forth across the top of the scale. Now leave the shutter speed alone and adjust the aperture. Again, you should see the arrow moving back and forth. Any time the arrow reaches the center of the scale, feel free to take a picture. This means that the photo is properly exposed. EXERCISE 2 - APERTURE / SHUTTER SPEED BALANCE In this exercise you'll really see the relationship between aperture and shutter speed. You're going to have to go outside to do this, and it's best if it's a nice sunny day. Set your camera to manual mode, and select an aperture of f/11. Your shutter speed should somewhere between 125 and 250 for the arrow to be in the center of the metering scale. Let's say that at f/11 your shutter speed for a correct exposure is Without changing aperture, change your shutter speed to 500 less light is entering the camera so the photo is now under exposed 2. Now change the shutter speed to 30 more light is entering the camera so the photo is now over exposed 3. Set the shutter speed back to 125 for a correct exposure 4. Without changing the shutter speed, set the aperture to f/22 this narrows the aperture (less light) so that your photo is under exposed 5. Change the aperture to f/5.6 the aperture is wider (letting in more light) and your photo is now over exposed 6. Set your aperture back to f/11 Page 22 of 23

23 7. Now change BOTH at the same time: set your shutter speed to 500 and your aperture to f/5.6. The faster shutter speed (less light) must be balanced by a wider aperture (more light). Your photo is once again correctly exposed 8. Return to your starting point of f/11 and shutter speed Now decrease the shutter speed to 30 (more light) you're probably able to guess which direction the aperture will go. It's going to NARROW to f/22 This is the aperture/shutter speed seesaw in action. EXERCISE 3 - FULL MANUAL MODE This last exercise is going to be the hardest. The first time that I forced myself to do this it was a painful experience, but once I was done I had learned a lot about aperture, shutter speed and exposure. So what is this difficult task? Set your digital SLR on manual mode and leave it there for an ENTIRE week. Take photos in a wide variety of lighting conditions so you get a feel for what you can and can't do with shutter speed and aperture. You'll be tempted to switch the camera back to an automatic mode, but try to hold off. The reason you'll be tempted to switch back to manual is because over the course of a week you're bound to find yourself in a position where you really want to get the shot. If you're just learning about aperture and shutter speed, you'll be worried that an important photo will be badly exposed. Here's the thing: it's OK to make some mistakes. In fact, it's required. Making mistakes is one of the best ways to learn something new. The more mistakes you make and correct early on, the less mistakes you'll make further down the road. It's also important to leave the camera on manual mode so that you learn the limitations of aperture and shutter speed. You may find yourself trying to take photos indoors, and realize that you can't open the aperture wide enough to get a shutter speed that won't cause blurry photos. You've just hit the limit of your camera and/or lens. It's important that you learn what some of these limits are, since next week I will be telling you how you can get around some of them. For now, just try to work in manual mode for a week. I guarantee that by the end you will feel pretty comfortable adjusting both aperture and shutter speed whenever you want.this knowledge opens you up to a world of photographic possibilities that can't be captured when the camera is set to automatic. Page 23 of 23