Early cameras were totally manual and did not have built in metering. In many cases exposures were decided based on experience and tables. Properly exposed photos were hit and miss. Many of the films had wide latitudes of exposure, in other words they were very forgiving. In the developing process many exposure errors could be corrected for as well.
Hand held meters eventually came on board, and taking properly exposed photos became much easier. With the advent to TTL metering life became even easier. Now you were measuring the light of the actual subject you were taking the photo of.
As cameras became more sophisticated the metering also followed suit. The modern digital camera can do amazing things, even under the most difficult lighting conditions. With the RAW file format you even have a more forgiving platform to work with. It is like the difference from slide to print film with the jpg to raw. Since I used to shoot slides I am used to having a narrow exposure range to work with. This is the reason that I shoot in JPG format.
In this chapter I will cover several different techniques that can be used to acquire just that right exposure, including Ansel Adam’s zone system.
Setting the right exposure on your camera can make a big difference in how your photographs turn out. Fortunately, knowing how to properly expose an image is easy once you learn a few basic terms and techniques.
What Is Camera Exposure?
Camera exposure is the overall brightness or darkness of a photograph. More specifically, it’s the amount of light that reaches the film or camera sensor when a picture is being taken. The more you expose the film or camera sensor to light, the lighter your photo will be. The less light, the darker your photo will be.
How Do You Determine the Correct Exposure?
There are three ways for your camera to control the amount of light that reaches the film or the image sensor; these three together constitute the exposure triangle:
- 1. Shutter speed: This is how long the shutter is open, expressed as a measurement of time. For example, 1/100 means that your shutter is open for 1/100th of a second. The longer the shutter is open, the brighter the photograph will be, as there was more time to let in the light. Learn more about shutter speed here.
- 2. Aperture: This is how big the opening is that lets light in, expressed in f-stops. F-stops are counterintuitive, because the larger the number, the smaller the opening. For example, f/2.8 allows twice as much light into the camera as f4, and 16 times as much light as f11. Aperture affects the depth of field: Larger openings create a shallower depth of field, while smaller openings make more of the image in focus. Learn more about aperture here.
- 3. ISO: This is how sensitive your camera’s sensor is to light, expressed in a number. The higher the ISO number, the more sensitive your camera will be to light. Learn more about ISO here.
4 Types of Exposure
Tinkering with the shutter speed, aperture setting, and ISO setting will produce different types of exposures, including:
1. Overexposure: Overexposure happens when the film or camera sensor is exposed to too much light. As a result, the photograph loses highlight detail and the bright parts become washed out.
2. Underexposure: Underexposure happens when the film or camera sensor is not exposed to enough light. As a result, the photograph loses shadow detail and the dark parts are almost all black.
3. Long exposure: Long exposure, also called time exposure or slow-shutter photography, is a technique that captures a subject over an extended period of time. The static elements of the photo contrast with the elements in motion, which create blurs, smears, and trails. Long exposure is commonly used in night photography.
4. Double exposure: Double exposure, also called multiple exposure, is a technique where the camera shutter opens twice to expose the film to different images. As a result, the photograph combines the two exposures into a single image, which are laid on top of one another.
How to Set Exposure on a Camera
In digital photography, you can set the camera exposure mode with the click of a button or turn of a dial. There are three main camera modes and exposure settings:
- 1. Manual exposure: You set a specific shutter speed, aperture, and ISO. This is useful if you want complete control of your camera settings and you have time to adjust them for each shot.
- 2. Shutter priority: You set a specific shutter speed and the camera automatically selects the aperture. This is useful when you want to control the depth of field.
- 3. Aperture priority: You set a specific aperture and the camera automatically selects the shutter speed. This is useful when you want to control the depth of field.
Both shutter priority mode and aperture priority mode have their uses and you’ll find yourself switching back and forth, depending on what you’re shooting. It often makes sense to set your ISO to Auto when you’re shooting in these modes so that the camera has more flexibility to make decisions to get the shot right.
What Is Exposure Compensation?
Sometimes you’ll be shooting in shutter priority or aperture priority mode, and because part of the frame is very dark or very light, the camera gets confused and doesn’t get the setting quite right on its own. If you switch to manual mode, you’ll have control over this. But if you’re in a hurry, you can use the exposure compensation dial on your camera to override the camera’s settings. By turning the dial, you’re telling the camera to under- or overexpose the shot, giving you the desired look.
The Best Camera Settings for 4 Different Types of Photography
Your digital camera may also have other pre-set exposure modes and settings for capturing specific types of photographs, including:
2. Landscape mode: Sets a high F-stop value to create a large depth of field, allowing the entire landscape to be in focus. Practice landscape photography techniques here.
3. Sports/Action mode: Sets a low F-stop value, fast shutter speed, and higher ISO to capture an athlete or a moving subject. Learn about sports photography here.
4. Night/Low-light mode: Sets a fast shutter speed, increased ISO speed, and may use the flash to better expose your subject in low light.
How to Use the Ansel Adams Zone System in the Digital World
The histogram shows 256 shades of gray. Besides pure black and pure white Ansel Adams used only nine shades to manipulate the contrast in his famous landscape photos. His zone-system can still be used for our modern digital photography.
Every landscape photographer has heard about Ansel Adams or will eventually come across that name. The famous American is mostly known for his black and white photos of Yosemite National Park. The 1941 photo Moonrise, Hernandez, New Mexico is probably his best-known photo.
One of the reasons why Adams is seen as a great photographer is because of his famous zone-system. With this system Adams was able to perfectly control the contrast in his black and white photos. Adams base rule was: “Expose for the shadows; develop for the highlights.”
The zone-system of Ansel Adams divides the photo into eleven zones; nine shades of gray, together with pure black and pure white. You could assume that a normal photo does not contain pure black and pure white. Therefor the nine shades of gray would be the only zones you can find in a photo.
Adams, who photographed in black in white negative film made sure to expose for the darkest parts of his scenery. This way he prevented to have pure black in the photo. When developing his photo paper, he made sure to manipulate the dark and light parts in his photo in such a way, that the shades of gray would follow his zone system.
Unfortunately, it is not possible to adapt his way of photographing in the digital photography. When we expose for the dark parts of the photo, the risk of overexpose light areas will occur. We all know, with digital photography overexposed areas cannot be recovered in any way. We all have heard the term for that kind of over exposure: blown out highlights.
This is also the main difference with analogue film. With analogue film, underexposure is not recoverable, and overexposure is recoverable. With digital photography it is just the way around, up to a certain point, of course. This means the base rule of Ansel Adams is not usable for digital photography.
Does this mean the zone-system is cannot be used for digital photography? Fortunately it can still be used. Instead of expose for the shadows, and develop for the highlights, we need to expose for the highlights and develop for the shadows. It is just a small, but very important change.
When using Lightroom you can use the sliders highlight and shadow to manipulate the shades of gray. The black point and white point slider will let you manipulate the boundaries, and locale adjustments make it possible to optimize any part of the photo to your liking. With proper post-processing you will end up with a perfect contrast in your black and white photo. It is almost as if we stepped into the darkroom of Ansel Adams again.
How about color? The zone-system of Ansel Adams is invented for black and white photography, of course, but it can be used for color photography as well. Sometimes it can be difficult to recognize the different highlights in a color photo. By temporary converting it to black and white, it might become possible to successfully use the zone-system of Ansel Adams again.
I have used this light meter for many difficult light conditions. I used it in every wedding that I ever did. It also helped me get just the right exposure in contrasty light conditions. If you are going to do studio work, I highly recommend getting one. It is not only a light meter but a flash meter as well. While this model is no longer available there are plenty of choices out there.
How Do You Know if You Have a Correct Exposure?
Setting a correct exposure is foundational to good photography. But what is a correct exposure?
A correct exposure is one that you are happy with. It means you have set the aperture, shutter speed, and ISO controls well. The result is that not too much light or too little light has made an impression on your camera’s sensor.
But choosing the correct exposure settings can be a bit like deciding what to wear for a night out. Or like determining how much chili to add to a Thai curry. You have to control the balance for it to be most effective.
Setting a correct exposure is a subjective process somewhat governed by technical considerations. You can automatically control the settings on your camera, or you can manage the aperture, shutter speed, and ISO in manual mode. Manual mode gives you more creative freedom to expose your subject. You can make it appear brighter or darker than it actually is. Doing this is one tool a photographer has to capture mood in their images.
A technically correct exposure is said to be one that contains detail in the shadows and in the highlights of a photo. The photo will also contain a good tonal range. Many photographers tend to strive for a technical proper exposure. This is fine if that’s what you like.
Finding the Balance of a Correct Exposure
Some genres of photography are best with technically correct exposures. Setting the exposure triangle so enough light hits the sensor. So detail remains in the shadows and the highlights. So the scene has a broad range of tonal values.
Other genres are more suited to photographers who like to make creative choices to create mood and set an atmosphere in their photos. If parts of the composition are very dark or bright, this adds impact to a photo.
There is always room for cross-over too, as the best photography is not confined to a set of rules. Capturing images exposed how you want them to be is one of the key creative components in photography. This should not be dictated by a bunch of technical rules. But don’t toss out the baby with the bathwater. Making a perfect exposure includes managing the camera’s exposure settings. And doing this with an understanding that results in the right amount of light hitting the sensor.
Too much light results in overexposure. The image is too bright. With too little light underexposure occurs and the image is too dark.
Your camera is a complicated piece of electronic hardware. THa’ts unless you’re using a old-school film camera. Either tool has limitations. You must manage the aperture and shutter speed and ISO to capture well-exposed images that you can then apply post-processing to.
Seek to find a happy place where the technical and creative aspects of photography collide. When they do, the combination makes the perfect exposure. One that’s a balance between the technical and creative aspects of photography.
Dynamic Range and Tone Range
Dynamic range is the luminance range a camera’s sensor is able to record, between black and white. The term ‘tonal range’ describes the number of tones captured in a photo.
Dynamic range is limited in any camera. In a single frame, the sensor in your camera is not capable of recording the same broad range of tones we can see with our eyes. This is why it’s important to manage your exposure triangle settings well.
The tonal range in a photo depends on:
-How much light is illuminating the scene.
-The quality of the light.
-The tonal range in the subject.
All of these factors must be considered independently but not exclusively. Combined they will help you produce well exposed photos.
How Much Light is Illuminating the Scene?
Whether you are taking photos where there’s a lot of light or not much light, this will have an influence on the camera settings you choose.
When you are using your camera on manual mode, you obviously will have to choose the best settings for a correct exposure. In any auto or semi-auto exposure modes, your camera will decide what settings to use. A faster shutter speed, a narrower aperture and/or lower ISO settings when a scene is well lit. In scenes with low light, a slower shutter speed, wider aperture and/or higher ISO are needed.
What About the Quality of Light?
Hard light or soft light? A scene illuminated by more than one light source, or with reflected light affecting it. These various qualities of light affect the tonal range that might be captured.
In hard light the tonal range is often greater, but there may not be a full range captured. This depends on the subject and the exposure settings. In hard light you can make an image that’s only black and white, with few or no mid-range tones.
Soft light is more likely to provide opportunities to create exposures with more mid-range tones. The shadows will not be so dark nor the highlights so bright as with hard light.
In scenes lit from more than one source, the tone range in a photo can be varied greatly when you have control over the lighting.
Exposure Settings Affect Tonal Range
Choosing a wider aperture for a shallow depth of field affects your exposure. As does opting for a fast shutter speed to freeze motion. Balancing an aperture of f2.8 requires a fast enough shutter speed. Setting your shutter speed to 1/15th of a second on a sunny day, you’ll need to adjust your aperture to a narrower setting. It will become challenging to achieve a shallow depth of field. Using ISO 100 will help, but may not be enough. Waiting until there is less light will help you get a correct exposure and a shallow depth of field.
To capture a perfect exposure and maintain creative control over aspects such as depth of field and motion blur, you need to understand how to use your camera well. You also need to understand metering well.
Metering for the highlights, mid-tones, or shadows produces varied exposures. Your modern digital camera has at least three exposure meter settings. These read the light in a scene differently. Let’s look at the main two metering modes that will help you get a correct exposure.
One will be averaged metering. Nikon calls this Matrix metering. Canon calls it Evaluative metering. The exposure meter reads the scene from many points and provides an averaged result.
Another mode is spot metering. In this mode, you can choose a small part of your photo to make a reading from. Using this mode you can read from a highlight, a shadow, or a mid-tone. With this mode you can be very precise with how you control the exposure of your image.
I often use averaged and spot meter modes to help me decide how to adjust my camera settings.
Learning to set your exposure well manually, or by using exposure compensation, takes time and practice. In my 365 Photography Course, I teach extensively on this topic. There are many practical examples and exercises designed to help you learn to make a correct exposure as often as possible.
How Varied is the Tonal Range in Your Subject?
How much tonal variation in the scenes you photograph must be considered when you want to make a correct exposure. Some subjects will have very little tone range. These are easy to expose for. In any auto mode you’re unlikely to need exposure compensation because the camera will predict a correct exposure.
Photography of subjects with deep shadows and bright highlights are more likely to challenge a camera’s dynamic range. You may not be able to set a correct exposure that captures detail in the brightest and darkest areas of your picture.
The histogram in your digital camera provides you with information to know when you are losing detail at either end of the tone range. When the histogram graph is bunched up to the left and hitting the top, you have lost detail in the darkest parts of your picture. When the histogram is bunched to the right and hitting the top, you’ve lost details in the highlights.
The histogram does not show you when you have a correct exposure, but it is helpful for showing you when detail is not being recorded in an image.
A Correct Exposure is What You Make It
As you can see, there are many aspects to capturing a well-exposed image. Leaving your camera on auto often produces an acceptably exposed image. When the light is diffused and your subject is not high contrast you are unlikely to need exposure compensation when on auto.
In manual mode, you can leave your meter set to averaged when the tonal parameters are narrow. In high-contrast scenes using your spot meter will help you decide the settings to use for a correct exposure.
High contrast means more decision-making. This is because the limits of illumination will be beyond your digital camera’s ability to record every tone.
Learning the technical aspects of exposure control and light helps you to make more informed choices. Once you are confident to manage your camera well you will be freer to become more creative with your photography.
HOW TO… What is a good exposure in photography?
We often talk about fine-tuning your camera settings and working with the light to achieve a good exposure… but what is a good exposure? This is a question new photographers always ask, and the truth is that there is no definitive answer!
Like all the arts, photography is inherently subjective, and the only correct exposure is the one that produces the effect that best matches your vision for an image.
We know this probably isn’t the answer you’re looking for, though, so let’s think about the question generally in terms of what most photographers try to achieve on average.
The other thing that complicates the answers is that different subjects often have different requirements. Sometimes a darker or lighter image is more desirable based on what you’re shooting.
This is especially true with high-contrast subjects. In these instances the brightness of your image will really depend on what part of your scene you want to stand out.
For instance, a brighter exposure will reveal more detail in the shadow areas of your scene, while a darker exposure will saturate colours more in your highlight areas, giving your image more punch.
Personally, I like to slightly under-expose for this very reason. Detail can always be teased out of shadow areas in post-processing, particularly if you shot raw files.
If you are in doubt as to how bright or dark your exposure should be, try shooting some bracketed exposures. You can also shoot several images with varying levels of exposure compensation. Here’s how…
Correcting your exposures
Often you’ll get your exposure wrong. It’s a fact of life for any photographer. When too much light reaches your sensor, your images will look overly bright. This is called over-exposure, and you notice it in bleached-out skies and flat colours.
In an under-exposed image not enough light is getting through to your sensor, and your images will look too dark.
Often these things can happen through no fault of your own. Your camera has a sophisticated metering system that reads the amount of light required for your scene and suggest an appropriate brightness. Usually it’s right, but sometimes it gets it wrong.
In these instance, there is an easy fix. Take a picture, look at it, and then use your exposure compensation control to make the next shot brighter or darker.
Typically you can dial in up to two stops of over- or under-exposure on your exposure compensation control, which is enough to dramatically change and image.
So what is a good exposure in photography?
- A good exposure in photography is generally the right combination of aperture, shutter speed and ISO that best reflects the subject you are trying to shoot.
- It helps to think of light and exposure in photography as you would filling bath tub with water. Your aperture is how far you turn the taps to increase the flow of water, while your shutter speed is how long you leave the taps running. Your ISO setting is the size of your tub.
- These exposure settings are reciprocal, which means that there is no single combination of settings that will give you the perfect exposure.
- Shooting a scene at 1/100sec at f/5.6, for instance, will let in the same amount of light as shooting that scene at 1/25sec at f/11. These settings will produce identical exposures, but of course things like depth of field will be different.
- It’s up to you to pre-visualise your image and decide how you want to portray elements like depth of field, and find the combination of exposure settings that let in enough light to reveal some detail and render rich colours that you are happy with.
How to always get exposure right – exposure settings explained
Unless you tend to stick to your camera’s Auto option, you’ll probably be aware of the many ways in which you can adjust exposure on your camera.
Those set in a particular way of working may forgo many of these for one or two of their preferred methods, but for those getting to grips with their camera, knowing which one to use in a given situation may be confusing.
Should you, for example, use exposure bracketing or exposure compensation? Or perhaps just shoot Raw and tweak exposure in post processing? If your images are a little dark, should you switch to a different metering pattern or would it be better to use a dynamic range adjustment setting? And what about the manual exposure mode?
The simple answer is that all of these can be useful, but there may be good reasons why you’d want to use one over another in a given situation. This is what the following article will explore.
Exposure compensation allows you to bias your an image’s exposure either towards underexposure or overexposure. You can typically adjust this in fine increments of 1/3EV or 1/2EV.
When to use it: This is useful when your camera consistently gives you a meter reading that doesn’t quite work for you.
So, if your camera is consistently capturing slightly dark images, for example, adjusting exposure compensation by +1EV or so will ensure they consistently turn out closer to what you’re expecting.
This could be, for example, because there are lots of bright or shiny elements in the scene that cause your camera to underexpose, or because you’re shooting darker details, which the camera may overexpose instead.
Exposure compensation is also useful when shooting a subject against a differently lit background, something that often fools a camera into giving inappropriate exposure.
Remember that if your conditions change you may no longer need this, so always remember to return exposure compensation back to 0 once you’re finished with it. Otherwise, it will continue to affect subsequent images.
Bracketing, or Auto Exposure Bracketing, usually results in one standard image, one image the camera deems to be unexposed, and an image the camera considers overexposed.
By giving you three images (or five, or seven, depending on what your camera allows and how you have it set up), you increase the chance of ending up with one image with the most appropriate exposure.
When to use it: Bracketing is useful in many situations. You can, for example, use this when lighting conditions are constantly changing, such as when shooting under flashing or constantly changing lights. Performance photography is one example of this.
If you’re using a tripod for a landscape or a similar scene, you can use this to take three identical images with different exposures, and blend them together later in post processing. This way you can end up with a single image with a wider dynamic range than what’s normally achievable by the sensor. This technique is known as High Dynamic Range (HDR) imaging, and this is the principle on which in-camera HDR options work.
Useful tip: If you know that you are unlikely to need one of the exposures when bracketing, you can use this feature in conjunction with exposure compensation to give you two exposures in the direction of your preferences.
So, let’s say you’ve activated bracketing by 1EV each way so that you have one standard image, one image underexposed by 1EV stop and one image overexposed by 1EV stop.
If you don’t think you’ll need the underexposed image – instead, you’d rather have one normal image and two overexposed ones – simply apply +1EV exposure compensation and the camera’s ‘underexposed’ image will be the standard one, leaving the other two images as overexposed by different degrees.
Manual-exposure mode (M)
This mode lets you change aperture and shutter speed independently of each other. This differs from options such as Aperture Priority or Shutter Priority, where changing one setting automatically affects the other.
Although the camera still uses the metering pattern you’ve selected to judge exposure, you will need to adjust each parameter yourself. This can take a little longer in practice, but it gives you plenty of control.
When to use this: This option is particularly useful when you may want to alternate between adjusting exposure by changing shutter speed and aperture. So, taking a moderately-lit scene as an example, you can quickly combine a wide aperture with a fast shutter speed, or a small aperture with a long shutter speed, or a value somewhere in the middle for each.
Manual exposure is useful when you don’t want the camera to change aperture or shutter speed if and when it deems it necessary. This is also useful when using flash, particularly as you need to ensure your shutter speeds stay at an appropriate level for flash synchronisation.
Shooting Raw images allows you to alter many settings after you’ve captured your images, with freedom to make those adjustments without degrading image quality.
While you still need to pay attention to your exposure when shooting Raw images, you can make tweaks to overall exposure, shadow areas, highlight details and so on once you’re sat in front of your computer, and take the time to get the exact results you want.
When to use it: If you’re in the habit of processing your images and card space allows, it’s a good idea to shoot in Raw images so that you always have a high-quality version.
You may not need to for general snapshots, but as Raw files contain more information than JPEGs, you’ll find that adjusting Raw files for more considered images will leave you with better-quality results than if you were to do the same to JPEGs.
There is, however, only so much information in Raw files that you can tease out of shadows and bring back in highlights, so you should aim to get things right in camera with an additional method, be it exposure compensation, bracketing or something else. Shooting Raw images should not be an excuse for laziness!
This is particularly the case with most compact cameras, whose latitude for processing Raw images is typically more limited than with cameras that offer larger sensors. The more appropriately exposed your image is to begin with the less you’ll have to adjust it in processing, and the more information your image stands to retain.
Dynamic Range Optimization
This option, which goes by names such as Active D-Lighting on Nikon cameras and Dynamic Range Optimizer on Sony’s models, adjusts exposure separately for particulars areas rather than for the image as a whole.
Although the exact way in which this works varies between different cameras, it typically allows you to get the exposure you want for shadows, midtones and highlights, so that details are visible throughout these different areas.
You will usually have a number of options so that its effect can be tailored to the scene, although you should also be able to set it to Auto to let the camera decide on what’s best.
When to use it: This option is best employed when your scene has a naturally wide dynamic range. So, a landscape with a good proportion of darker and lighter areas, for example, or perhaps when shooting indoors, where you want darker interior details balanced with brighter ones appearing through windows. It’s in these scenes where this setting will have the greatest effect. The strongest settings can noticeably reduce image contrast, so only use these if necessary.
Centre-weighted and spot metering
The default matrix, or evaluative, metering mode takes all areas of the scene into account when judging appropriate exposure, but switching to another metering pattern may be a better idea if you’re shooting many images of the same subject in an atypical set of conditions.
The centre-weighted metering option biases its exposure towards the main subject but also considers the surrounding areas, while the spot metering option only uses a very small proportion of the whole scene to judge exposure for the whole image.
When to use it: Centre-weighted metering is ideal when your subject is lit in a different way to the background, such as when shooting portraits against a bright sky. Using the standard evaluative metering pattern here is likely to lead to underexposure, as the camera may be fooled by the brighter areas behind the subject.
Spot metering is useful when the subject occupies only a small portion of the frame, such as when capturing an insect on a blade of grass. This ensures the exposure is completely accurate for the subject at the expense of all other areas.
Other options on modern cameras may include highlight-weighted metering. This is a good metering pattern to use when you’re looking to prevent highlights from blowing their details in key areas, such as a person’s face or a bride’s wedding dress. This is particularly useful when working with harsh spotlights, as you may encounter with live-performance photography.
AE Lock (AE-L)
Unless you use the manual exposure mode, your camera will be changing the aperture or shutter speed (or both) as it deems necessary to produce the most appropriate exposure for the scene.
The AE Lock option allows you to quickly lock the exposure to a particular set of settings so that you can use them for all subsequent frames.
When to use it: AE Lock is useful whenever you meter a scene and achieve the exposure you’re happy with but then need to change your position or framing, which could cause your camera to give you a different meter reading.
It’s also useful when something you cannot control in the scene is causing meter readings to fluctuate, such as flashing lights or areas changing in brightness around a subject. Furthermore, you may wish to use this when using centre-weighted or spot-metering patterns, where slight changes in your position can cause the meter reading to change.
Everything You Need to Know About the Exposure Triangle
What is the exposure triangle! And you are asking me? The exposure triangle… is the core of photography. And no, we’re not talking about how to give exposure to you work by combining a stunning photography website, engaging social media accounts, and impressive people skills. This is about empowering your creativity by translating your vision into an image.
Regardless of your skill level and preferred genre, learning how to control the exposure is a must to capture good photos. Even those with incredible post-processing skills will find that it’s nearly impossible to turn a badly exposed picture into a great photo. And the secret to nailing the perfect exposure is understanding how the exposure triangle works.
What is the exposure triangle?
Exposure triangle is the photography term that describes the relationship between the three elements that determine the exposure of a photo: shutter speed, aperture, and ISO. The way these three factors are balanced determines the final appearance of a shot and the feelings it evokes.
Knowing its importance, it shouldn’t be a surprise to hear that the exposure triangle is one of the hardest photographic skills to master. On the bright side, once you fully understand it there’s nothing you won’t be able to do.
Before we dive deeper into each of the variables involved, take a look at this visual representation of the exposure triangle and see how each side affects the image.
Measuring light in stops
The amount of light that reaches the camera sensor is measured in stops. This concept was created to unify the three elements involved, as each of them calculates different parameters. A stop doubles or halves the amount of light that reaches the camera sensor. Increasing one stop in any of the three variables results in twice as much light reaching the sensor. Decreasing one stop cuts the amount of light captured by half.
Depending on the camera that you are using, you might be able to work with 1/2 and 1/3 increments. While the creative flexibility might allure you to select this option right away, you should try to master the basics before increasing the difficulty of the task in hand.
If you’re used to shooting in semi-auto modes, you might have realized that these stops are what allow you to modify the exposure with EV compensation in Program, Aperture Priority, and Shutter Priority modes.
The first side: shutter speed
The only reason that we’re calling this the “first side” is because shutter speed is usually the easiest variable to understand. The shutter speed measures the length of time that the camera sensor is exposed to light. During this time, the shutter is open and the position of objects within the frame is captured. That means that if something is moving during the exposure, it will appear blurred on the image.
“Why would anyone want a blurred photo?” You may ask. Think about those stunning night pictures with light trails or the beautiful landscape photos that capture smooth rivers and waterfalls. Learning how to shoot in slow shutter speeds will allow you to see the world from a completely different perspective.
On the other hand, higher shutter speeds are used to freeze the action. This is especially useful to capture unique instants, such as a breaking wave, or avoid blurriness when you cannot use a tripod, like in underwater photography.
While each shot has its own requirements, here are some general guidelines on when to use different shutter speeds, from faster to slower:
1/500 to 1/2000: flying birds
1/250 to 1/1000: sports
1/250 to 1/500: children and pet photography
1 to 8 seconds: motion blurred water
20 to 30 seconds: clear stars
10 minutes and up: star trails (you’ll need to shoot in bulb mode)
The second side: aperture
Aperture is the size of the opening through which light enters the camera. The bigger the opening, the more light captured. The concept is just as easy to understand as shutter speed, if not easier. However, the way it works is slightly more complicated than its counterparts.
For starters, aperture is measured in f-stops. This unit is the result of dividing the focal length of the lens by the diameter of the opening. As numbers get higher, aperture becomes smaller and lets less light in. To make things a bit more complicated, the numbers are doubled every two stops – meaning that the amount of light is four times higher every time the number is doubled. This might sound incredibly confusing right now, but you’ll get the hang of it as you practice.
The other main challenge of mastering the use of aperture is understanding how it affects depth of field. Wider openings, lower numbers, result in shallow depth of field, making it a great tool for portrait photography. Contrarily, narrower openings offer a wider focus depth. The reason behind this is physics, and much too complex to be synthesized in a couple lines. For now, focus on mastering the exposure triangle. There will be plenty of time to find out why things work the way they do.
The third side: ISO
Last, but not least, is ISO which defines how sensitive the camera sensor is to the light that reaches it. In film photography, ISO is more of a constant than a variable as it depends on the film roll sensitivity and cannot be changed once it’s inside the camera. On the contrary, digital cameras allow photographers to easily modify the ISO. Technically, it would actually be more accurate to call it “post processing gain” as the actual sensitivity cannot be changed.
While the three variants of the triangle are given the same weight of importance and need to be balanced, the purpose of modifying the ISO is different than that of shutter speed and aperture. The first two variables are considered creative tools and have a direct effect on the aesthetics of the image. However, ISO is actually considered a way to balance the overall exposure to achieve the desired effect of the previous settings.
Essentially, you’ll want to increase ISO sensitivity when the values you need on shutter speed and aperture are not enough for a good exposure. One of the most clear examples is astrophotography, as it is necessary to use a high ISO in order to compensate for the appropriate shutter speed needed to capture gleaming stars.
The downside of increasing ISO is that it results in images with more noise and less detail. Because of this, it is recommended to stick to low ISO numbers in order to get the best results.
Getting the right exposure
No pressure, but there’s only one mathematically right exposure for each scene. Shooting above this value will result in overexposure and loss of detail on the highlights. On the other hand, shooting below it will crush the shadows and give an underexposed image. Even if you’re actively trying to get one of these effects, it is always better to aim for a balanced exposure in order to capture as much information as possible. After all, it is easier to modify exposure levels in post-processing than to create details that are simply not there.
The good news is there are hundreds of potential settings that can be used to achieve the perfect exposure. And each of them gives a completely unique result. It’s completely up to you to decide how to combine shutter speed, aperture, and ISO to capture the scene based on your vision.
There are two main ways to find the right exposure for a scene: a light meter and the camera histogram. A light meter is a photography accessory that allows photographers to measure the light and find the correct exposure settings based on their preferences. For example, you can preselect your ISO and shutter speed and use it to measure the proper aperture. In contrast, the histogram is built into your camera but might take a bit more trial and error. Simply aim for a balanced curve that extends across its whole length without cutting off at any point.
The most important thing when it comes to exposure is understanding that you must always balance the three variables of the exposure triangle. If you modify one of the settings, you must compensate for the additional or lost light by decreasing or increasing one (or both) of the others.
fstoppers.com, “How to Use the Ansel Adams Zone System in the Digital World.” By Nando Harmsen; photographycourse.net, “How Do You Know if You Have a Correct Exposure?” By Kevin LJ; camerajabber.com, “HOW TO… What is a good exposure in photography?”; digitalcameraworld.com, “How to always get exposure right – exposure settings explained.” By Matt Golowczynski; wix.com, “Everything You Need to Know About the Exposure Triangle.” By Judit Ruiz Ricart; masterclass.com, “Photography Basics: What Is Exposure? Understanding How Exposure Affects Your Photographs.” by MasterClass;