Contrast detection vs phase detection. What are these autofocus modes in our cameras and why do they matter? Contrast detection autofocus (CDAF) and phase detection autofocus (PDAF) are two different methods of focusing that are commonly used in digital cameras.
While both methods have their own advantages and disadvantages, they work in fundamentally different ways. In this article, we will take a closer look at the differences between CDAF and PDAF and help you understand which method is best suited for different types of photography and videography.
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CDAF: Contrast detection autofocus is a method of focusing that is commonly used in digital cameras, particularly point-and-shoot cameras and smartphones.
In contrast to phase detection autofocus, CDAF uses the image sensor itself to determine the correct focus distance.
The basic principle behind CDAF is simple: the camera compares the contrast of the image in different areas of the frame, and adjusts the lens until the highest contrast is achieved.
This is done by taking multiple images at different focus distances, and then analyzing the images to determine which one is the sharpest.
When the camera is in autofocus mode, it will typically start by focusing at the center of the frame, and then move the lens back and forth to find the point of maximum contrast.
This process can take a fraction of a second, but it can be slower than phase detection autofocus, especially in low-light conditions or when focusing on a low-contrast subject.
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CDAF is also less precise than phase detection autofocus, as it can be harder to detect small differences in contrast. This can make it more challenging to achieve a sharp focus on small or low-contrast subjects, and it can also result in more hunting back and forth as the lens tries to find the correct focus distance.
PDAF: Phase detection autofocus is a method of focusing that is typically found in DSLR and mirrorless cameras. Instead of using the image sensor to determine the focus distance, PDAF uses a separate sensor, called a phase detection sensor, which is located in the camera body.
The phase detection sensor splits the incoming light into two separate beams, and then compares the phase difference between the two beams. This allows the camera to quickly and accurately determine the correct focus distance.
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PDAF is generally faster than CDAF, as it can quickly and accurately determine the correct focus distance without needing to take multiple images and analyze them. This makes it well-suited for capturing fast-moving subjects or shooting in low-light conditions.
PDAF is also more precise than CDAF, as it can detect small differences in the phase of the incoming light. This allows the camera to achieve a sharper focus on small or low-contrast subjects.
Which method is best for you? Both CDAF and PDAF have their own advantages and disadvantages, and which method is best for you will depend on the type of photography or videography you are doing.
CDAF is best suited for situations where precision is not as important, such as landscape or portrait photography. It also works well in live-view mode, which is handy for videography and photography using the LCD screen.
PDAF, on the other hand, is best suited for situations where speed and precision are important, such as sports or action photography. It is also well-suited for capturing fast-moving subjects or shooting in low-light conditions.
In conclusion, CDAF and PDAF are two different methods of focusing that are commonly used in digital cameras. While both methods have their own advantages and disadvantages, they work in fundamentally different ways. It’s worth checking your camera make and model to find out what type of focussing system it uses.
Many new cameras will use a hybrid system of both PDAF and CDAF, depending on what you’re focussing on. It may use PDAF to acquire the focus and then fine tune it with CDAF.