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What is Exposure?Exposure is the amount of light collected by the sensor in your camera during a single picture. If the shot is exposed too long the photograph will be washed out. If the shot is exposed too short the photograph will appear too dark. Almost all cameras today have light meters which measure the light in the given shot and set an ideal exposure automatically.
Exposure is a combination of three fundamental camera settings (often referred to as the exposure triangle): 1. Shutter speed 2. Aperture 3. ISO Mastering their use, however, is an essential part of taking your photography skills to the next level and beyond. |
How do I know which camera settings to use?
Mastering the art of exposure is something that takes a lot of practice. The settings you choose will have an effect on how your photograph will look and depends entirely upon the effect you are trying to capture. Many different combinations will give the right exposure, but each will have differences is depth of field, motion blur, contrast, image quality, etc. This interplay of different factors can seem complicated, and many people opt instead to use their camera's automatic mode to do the work for them.
The great thing about digital cameras is that they are the ideal testing bed for learning about exposure. You can take as many shots as you like and they not only allow you to shoot in Auto mode and Manual mode – but most offer Semi-Automatic modes like Aperture Priority, Shutter Priority & ISO priority which allow you to make decisions about one or more elements of the triangle and let the camera handle the other elements.
Once you understand the different settings you'll be able to take more control over your photos, producing better shots in the process. Let's take a look at each of the three elements in the exposure triangle to see how they specifically impact your image...
The great thing about digital cameras is that they are the ideal testing bed for learning about exposure. You can take as many shots as you like and they not only allow you to shoot in Auto mode and Manual mode – but most offer Semi-Automatic modes like Aperture Priority, Shutter Priority & ISO priority which allow you to make decisions about one or more elements of the triangle and let the camera handle the other elements.
Once you understand the different settings you'll be able to take more control over your photos, producing better shots in the process. Let's take a look at each of the three elements in the exposure triangle to see how they specifically impact your image...
What is Shutter Speed?
Shutter speed, also known as “exposure time”, stands for the length of time a camera shutter is open to expose light into the camera sensor. If the shutter speed is fast, it can help to freeze action completely. If the shutter speed is slow, it can create an effect called “motion blur”, where moving objects appear blurred along the direction of the motion. Shutter speed is generally measured in fractions of a second. A shutter speed of 1000 means the shutter is open for 1/1000 of a second.
If you want to freeze your object and have it look sharp, you will need to assess its speed. The faster your object moves, the faster you need to set your shutter speed. Slower shutter speeds are normally used and/or needed for landscape, architectural, night, still life or "special effect" photography. Use of a tripod is recommended for shutter speeds less than 1/60th of a second to avoid blurry images. Whether you are trying to show the silkiness of a waterfall or the movement of the stars at night, a slower shutter speed adds artistic drama while offering a creative solution to the dilemma of incorporating motion into the “still” photograph.
If you want to freeze your object and have it look sharp, you will need to assess its speed. The faster your object moves, the faster you need to set your shutter speed. Slower shutter speeds are normally used and/or needed for landscape, architectural, night, still life or "special effect" photography. Use of a tripod is recommended for shutter speeds less than 1/60th of a second to avoid blurry images. Whether you are trying to show the silkiness of a waterfall or the movement of the stars at night, a slower shutter speed adds artistic drama while offering a creative solution to the dilemma of incorporating motion into the “still” photograph.
What is Aperture?
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In optics, an aperture is a hole or an opening through which light travels. In photography, aperture refers to the diameter or size of the lens opening rather than the opening itself. Aperture is expressed as F-stop, e.g. F2.8 or f/2.8. The smaller the F-stop number (or f/value), the larger the lens opening (aperture).
In simplest terms, when you hit the shutter release button of your camera a hole opens up that allows your camera's image sensor to capture the scene you want. The aperture that you set determines the size of that hole. The larger the hole, the more light that gets in – the smaller the hole, the less light. Aperture has a big impact upon depth of field (see below). A large aperture (ex. f/1.8) will decrease the depth of field while a small aperture (ex. f/22) will give you a much larger depth of field. When you shoot in Aperture Priority mode, you set the lens aperture, while the camera automatically sets the shutter speed.
In simplest terms, when you hit the shutter release button of your camera a hole opens up that allows your camera's image sensor to capture the scene you want. The aperture that you set determines the size of that hole. The larger the hole, the more light that gets in – the smaller the hole, the less light. Aperture has a big impact upon depth of field (see below). A large aperture (ex. f/1.8) will decrease the depth of field while a small aperture (ex. f/22) will give you a much larger depth of field. When you shoot in Aperture Priority mode, you set the lens aperture, while the camera automatically sets the shutter speed.
What is ISO?
Your camera's ISO setting controls how sensitive its sensor is to the light that reaches it. It is one of the crucial factors which goes into determining a photograph's exposure as well as the overall image quality. Most people tend to keep their digital cameras in ‘Auto Mode’ where the camera selects the appropriate ISO setting depending upon the conditions you’re shooting in (it will try to keep it as low as possible) but most cameras also give you the opportunity to select your own ISO. Switching to a higher ISO setting makes your sensor more sensitive to light, meaning that you can take photos in darker conditions without the need to use a flash or tripod. However, a high ISO also creates more noise, reducing the image quality.
You should always aim to use the lowest ISO setting possible, because this will give you the best image quality. However, your first priority should be getting a fast enough shutter speed, because a blurry photo is a lot more distracting than one with a bit of digital noise.
Situations where you might need to push ISO to higher settings include:
You should always aim to use the lowest ISO setting possible, because this will give you the best image quality. However, your first priority should be getting a fast enough shutter speed, because a blurry photo is a lot more distracting than one with a bit of digital noise.
Situations where you might need to push ISO to higher settings include:
- Indoor Sports Events – where your subject is moving fast yet you may have limited light available.
- Concerts – also low in light and often ‘no-flash’ zones
- Art Galleries, Churches etc- many galleries have rules against using a flash and of course being indoors are not well lit.
What is Depth of Field?
Depth of field, also sometimes known as depth of focus refers to the range of distance that appears acceptably sharp in a photo. It varies depending on camera type, aperture and focusing distance.
By changing the aperture in the lens, you can make the resulting picture have more of the picture in focus from near to far, or you can limit the picture’s focus on one place. In some cases, it may be desirable to have the entire image sharp, and a large DOF is appropriate. In other cases, a small DOF may be more effective, emphasizing the subject while de-emphasizing the foreground and background.
At ƒ1.8, ONLY the focus point will be defined with things in front of and behind your focus point becoming softer or blurry. This is a very nice way to bring attention to the subject.
At ƒ22, the focus will seem to be sharp from very close to the camera to pretty much infinity. This is great for giving a sense of the place you shot the image, or for including many people in the image and keeping everyone clearly in focus.
By changing the aperture in the lens, you can make the resulting picture have more of the picture in focus from near to far, or you can limit the picture’s focus on one place. In some cases, it may be desirable to have the entire image sharp, and a large DOF is appropriate. In other cases, a small DOF may be more effective, emphasizing the subject while de-emphasizing the foreground and background.
At ƒ1.8, ONLY the focus point will be defined with things in front of and behind your focus point becoming softer or blurry. This is a very nice way to bring attention to the subject.
At ƒ22, the focus will seem to be sharp from very close to the camera to pretty much infinity. This is great for giving a sense of the place you shot the image, or for including many people in the image and keeping everyone clearly in focus.
Should I shoot JPEG or Raw?
Most medium to high-end digital cameras will offer you a choice of file formats in which to save your images. But how to decide which file format is best for you? As far as quality and versatility goes, nothing beats a RAW file. RAW files are uncompressed (which means they are large) and contain the complete data from the camera’s sensor. This allows for the most versatility when it comes time to open your image in a post processing software such as Photoshop. But having said that, RAW files also take the most work to get a great-looking image and they are not suitable for printing directly from the camera without post processing.
In comparison, a JPEG is processed by your camera. It is compressed and fairly small in file size. Shooting in JPEG will allow to capture 2 or 3 times the number of images you could shooting in RAW. A JPEG file is immediately suitable for printing, sharing, or posting on the Web and quite often needs no post-processing correction. However, if you do manipulate the image in any way, you will lose data each time an edit is made.
Guess which has more processing power: your digital camera or your computer? Shooting in RAW will give you much more control over how your image looks and you will be able to correct any mistakes you may have committed when you took the photograph, such as anything under- or over-exposed.
If you want to do minimal or no post processing, then you definitely want to shoot in JPEG. Taking a picture in RAW is only the first step in producing a quality image ready for printing but if quality is of the utmost importance and you want to get every bit of performance your DSLR can offer then you should be shooting in RAW. Keep in mind your archival space, as backing up large batches of RAW files can be arduous.
If capacity is not an issue at all (1 GB and 2 GB flash cards are getting cheaper every week) you might consider shooting in Raw + JPEG, just to cover all the possibilities.
In comparison, a JPEG is processed by your camera. It is compressed and fairly small in file size. Shooting in JPEG will allow to capture 2 or 3 times the number of images you could shooting in RAW. A JPEG file is immediately suitable for printing, sharing, or posting on the Web and quite often needs no post-processing correction. However, if you do manipulate the image in any way, you will lose data each time an edit is made.
Guess which has more processing power: your digital camera or your computer? Shooting in RAW will give you much more control over how your image looks and you will be able to correct any mistakes you may have committed when you took the photograph, such as anything under- or over-exposed.
If you want to do minimal or no post processing, then you definitely want to shoot in JPEG. Taking a picture in RAW is only the first step in producing a quality image ready for printing but if quality is of the utmost importance and you want to get every bit of performance your DSLR can offer then you should be shooting in RAW. Keep in mind your archival space, as backing up large batches of RAW files can be arduous.
If capacity is not an issue at all (1 GB and 2 GB flash cards are getting cheaper every week) you might consider shooting in Raw + JPEG, just to cover all the possibilities.
Read more tips at : http://digital-photography-school.com/learning-exposure-in-digital-photography#ixzz20KCnts2i