Apply digital filters for autofocus. What you need to know about focus. Manual focus. Fine tuning autofocus

How does autofocus work on a smartphone? What type of autofocus works best? Pros and cons of laser, phase and contrast AF. Why is dual-pixel so good?

How does autofocus work on a smartphone? There is no simple answer to this question. It is necessary to deal with each type of autofocus, to study the features of a particular focusing technology. Only then can any conclusions be drawn. Therefore, now we will talk about the varieties of auto focus technologies, and about the advantages and disadvantages of each of them.

What is camera focus and autofocus

Everything is simple here: the lens of the lens refracts the rays and collects all the light at one point - the focus. And if the matrix sensor is located at this point, then the frame is more detailed and of high quality. Naturally, all photographers use this physical phenomenon. They bring some part of the frame into focus, adjust the lens manually and focus the viewer's attention on the foreground or background, the main subject or a minor detail. The rest of the picture will be blurry.

Well, novice photographers can use the auto focus system, when the automation captures one or more objects in the frame “in focus”, controlling both the lens and the matrix. And these objects (or object) are as sharp and detailed as possible. And no skill and sense of the frame is no longer needed here.

That's probably why digital photography became more popular than the film-and-paper version of the art. After all, autofocus in the camera of a phone or a cheap camera allows you to take a detailed picture without any extra effort. The whole process comes down to simple rule: point and click.

Varieties of autofocus and the basic principles of their work

The camera lens focuses the rays reflected from an object located in the space in front of the lens. When focusing, the camera focuses on the distance to the object and on the intensity of the glow emanating from it. Today, there are two types of auto focus modes:

Active option - it is based on measuring the distance using a rangefinder locator.
Passive option - it works with a light beam, measuring its intensity.

The first (active) mode uses laser infrared or ultrasonic radiation with a known speed of wave propagation in air. The emitter module emits a directed stream, which is reflected from the object and is captured by the receiver module after a certain period of time. The autofocus calculator then multiplies this time by the known wave propagation speed and divides the result by two to get the exact distance. By directing the emitter to the desired area, the user receives optimal focus, focusing the viewer's attention on this particular area of the photo.

The second (passive) mode is arranged somewhat differently. It uses special sensors (photodiodes) that measure the intensity of the glow and a special processor that determines the focus by the value of this parameter. In practice, it looks like this: the sensors fix the intensity of the glow, then the processor shifts the focus, after which the intensity is re-measured, if the flux density has increased, then the focus is considered acceptable. If not, the focus is shifted again. And so on until the maximum intensity is found. In matrices serious cameras up to 40-60 photodiodes are present.

Based on these principles, the most famous focusing systems work: phase, laser, contrast and dual-pixel. And further in the text, we will evaluate each option along the way, evaluating their basic advantages and disadvantages.

Advantages and disadvantages of laser autofocus

In this case, a laser emitter and receiver are built into the phone camera model. The first generates a narrow beam, the second receives the reflected signal. As a result, the speed of focusing is reduced to thousandths of a second. Usually we are talking about 250-300 milliseconds, since the laser propagates at the speed of light.

The main advantage of the laser focus is high speed module responses, and the main drawback is frequent failures. A narrowly focused laser emitter sometimes "shoots" past the target, and the reflected signal is easily lost, especially in open spaces. Therefore, laser autofocus in a smartphone camera in most cases works in tandem with a phase or contrast guidance option.

Features of phase focusing

The technology is based on splitting the beam passing through the lens into two streams. This is done in order to measure the distance between streams passing through opposite edges of the lens. If this distance is within certain values specified in the data array, the picture is considered to be focused. To fix the distance, special sensors are used that react to light. Their signals are processed by the processor, which compares the read parameters with the base data array and gives a signal to shift the focus in the right direction.

The main advantage of the technology is the willingness to focus on a moving object. In addition, this option is faster than contrast autofocus. And this system can also be used to calculate such a parameter as depth of field.

The main disadvantage of phase technology is its complex implementation. The system of prisms, mirrors, lenses requires ultra-precise physical alignment and no less scrupulous program settings. In addition, the accuracy of such a focus depends on the lens aperture, and mobile phones have big problems with this parameter.

Pros and cons of contrast focus

The technology does not change either the matrix or the optical system of the smartphone camera. Either the entire photosensor or part of it is used as a sensor. The processor reads the current histogram from the sensor and evaluates the contrast of the frame. And then the lens is given a command to shift the focus, after which the histogram is read again with a reassessment of the contrast. And the whole cycle is repeated until the maximum level of contrast is reached in the selected area of the frame, which is focused.

The main advantage of the technology is a combination of ease of implementation, low cost of construction and compact size. Such autofocus is used by all manufacturers of budget smartphones.

The key disadvantage of this option is the very slow speed. Sometimes the processor goes into the eternal “hunting for focus”, which ends in the loss of a rare frame.

Dual Pixel Technology

This focusing technology is used in expensive SLR cameras. In mobile devices, it is still used only in Samsung's flagship models, deliberately lowering the resolution of the photographic matrix while increasing its physical dimensions.

These tricks are due to the desire to attach an individual sensor to each pixel of the photographic sensor, which reacts to the intensity of the glow. Then the signals from the sensors are processed according to both the phase and contrast focusing algorithms, achieving not only a perfectly sharp, but also the most contrasting image.

If in the case of the classic phase focus, the sensors account for no more than 10% of the total number of pixels in the camera, then in the case of the Dual Pixel they are divided in a 50/50 ratio. Simply put, each pixel is a photosensitive element and a sensor at the same time. This technology provides more accurate and faster focusing.

Of the disadvantages of Dual Pixel, it should be noted that such solutions are very difficult to implement. Only flagship devices are equipped with such tricks, for example, devices from the Samsung S-series (from the seventh model and higher). There is something similar in the latest iPhones (from the sixth model and up), but Apple calls this focusing technology Focus pixels, and it is closer to conventional phase detection autofocus than to Dual Pixel.

Auto focus is a mandatory part of the camera of most modern mobile phones. This feature is necessary because it is often the only way to sharpen a picture to get the frame of the required quality. And while in full-fledged cameras it is often possible to adjust the focus manually, most mobile phones do not have such an opportunity, and therefore it will not work to improve the quality of the picture in other ways.

Using autofocus

In mobile phones, the auto focus function is enabled by default and is used when taking any picture. To focus, just press the function key of the device to take a picture. Also, many fix the current frame when you click on the corresponding touch screen. The device will automatically detect the subject you want to focus on and take the correct picture.

Modern mobile phones also support a more complete auto focus mode, which is implemented using the camera's shutter button. To make adjustments, the user needs to lower the key to approximately half. This allows the camera to focus, adjust sharpness and brightness.

After autofocus is triggered and the corresponding signal is received, the user can press the button to release the shutter. The focus button on touch screens works in a similar way - the user needs to press and hold the key with their finger until the camera adjusts focus. By releasing the finger, the user will take a picture, which will be stored in the device's memory.

Flaws

However, there are some drawbacks to autofocus technology. Often auto focus cannot determine the subject to which sharpening is to be performed. Sometimes the camera is unable to find multiple subjects to focus on, which also lowers the quality of the picture.

However, with the release of each new mobile device, auto focus technology is improving and its functioning is improving, which allows you to take good and high-quality shots. Also, some modern devices are equipped with manual focus settings, which will solve these problems when taking some pictures.

In all digital cameras, whether it's a cheap soap dish or an expensive DSLR, there is auto focus. Why then do you need a manual one, if the system itself does a good job? A logical question, and the answer to it is also logical: often auto focus does not work correctly, sometimes very slowly and inaccurately. Therefore, knowing how focusing works and how to set it up greatly expands the creativity of any photographer and, who would have thought, ensures correct focusing in different situations.

Manual focusing allows you to highlight the main subject in the frame or, on the contrary, draw the viewer's attention to the details of the picture. Today, that's what we're going to talk about - about the focus and situations when it is most appropriate to use manual focus.

Focus points

The focus is a certain point where all the rays reflected from the image converge. Therefore, in order for the image to be "in focus", the focus point must be on the camera's matrix. Focusing allows you to prioritize the image, riveting the viewer's attention to the main objects, rather than minor details.

The focus point is a point in space, and it is in it that the subject is placed. The image of this object is clear on the matrix. The choice of point is determined by the photographer's decision to select the most important detail in the frame and direct the viewer's full attention to it.

In expensive SLR cameras (even mirrorless ones), the user is offered a choice between specific focus points. It is also possible to select all at once. If you choose focusing on one point, then the picture will be sharp only in that part of the image that coincides with the selected point in the viewfinder. If you choose focusing on all points at once, then the automation itself will select the focus in accordance with its own intelligent algorithms. Often the automation misses and spoils the picture.

In accordance with the class of the camera, there may be many or no focus points. Inexpensive DSLRs entry level equipped with 11-point focusing systems. A great example is the camera. Canon EOS 700D.

Expensive professional cameras have 61 focus points. Example - camera Canon EOS-1D X.

Autofocus miss

Do not think that such a phenomenon is rare. Even in expensive DSLRs, an autofocus miss is not ruled out. This is due to the fact that the focus is selected automatically, and often the camera simply “does not know” the goals of the photographer and, therefore, focuses on the wrong object that the photographer intended. Sometimes the system cannot determine a specific focus point, and then the focus buzzes, trying to "aim" at an unknown target. The applied intelligent focusing algorithms often provide sharpening of irregular objects in the background or in the middle ground.

Still, auto focus is important. It's not always possible to manually aim at objects and fiddle with settings, especially if the events in the frame happen quickly and do not allow you to wait. Therefore, in reportage shooting, automatic focusing on all points will always come in handy.

Interesting: in compact inexpensive soap dishes, there is practically no problem with focusing. "Soap dishes" usually focus on infinity, with the result that every object is in focus - the object in the foreground, and the horizon, and the middle ground. However, this greatly limits the creative potential of the camera and the photographer himself - it is impossible to single out a specific object and direct all attention to it. So this is more of a disadvantage than an advantage.

Applying focus by beginners

Professional photographers, when talking to beginners, recommend using just one central focus point instead of all-point autofocus. It is much easier for a beginner to determine the center of the frame at the time of shooting through the optical viewfinder of a DSLR.

In this case, the technique for taking a picture will be as follows: first, choose the main subject - it should turn out sharp in the frame. Then, in the viewfinder, place it in the very center of the frame, aligning it with the focus point (which we have in the center). Next, hold down the shutter button halfway to lock autofocus. Most cameras make a characteristic squeak at the same time. Then the shutter button is clamped to the end.

The result is a photo with a sharp subject right in the center of the frame, the rest of the details are out of focus, less sharp. Little attention is paid to them. In artistic terms, such pictures look very good. In this case, it was about using the center focus point, but it could easily be the right or left point. Then the main subject would have to be placed on the right or left side of the frame to be in focus.

Auto Focus Modes

Each company that manufactures photographic equipment uses its own intelligent focusing algorithms. They give approximately the same result. The modes in which these algorithms are used can be called differently. For instance, in camerasCanon have modeOneShot- it is intended for photographing stationary and motionless objects. For objects in motion Canon has provided a modeAlServo- slightly different algorithms for determining the main objects and focusing will already be used here.

AtNikon these modes are called differently:SingleServo - for stationary stationary objects,continuousServo - for moving. Also, both brands have predictive focus modes, when the system tries to predict the further movement of the object in order to ensure the correct focus.

However, despite the development of technology and the improvement of algorithms, autofocus often misses. Here are examples of photos with focus errors:

Quite often, photographers have to deal with autofocus miss, and the reasons for this are often the same: shooting conditions that "cheat" the focus system.

When is it appropriate to use manual focus?

The very first and banal moment when it is best to manually focus on an object is in low light. Often in low light, the camera lens starts to rotate back and forth and cannot specifically identify the correct object. However, this problem is partly solved thanks to autofocus illumination (the foreground is highlighted, which allows you to ensure correct focus), although not completely.

Macro is another mode in the camera when it is better to manually focus on the subject. The problem is that with macro photography, work goes on in very narrow ranges of sharpness, respectively, any inaccuracy will ruin the picture.

Portrait photography. Usually there are no problems here, because in this mode the system focuses on the eyes of the model. but professional photographers sometimes manual focus is used to highlight the line of the lips or another part of the face. However, this is a completely different story.

The most common complaints I hear from most photographers of any level are "my images aren't sharp" and "I can't get focus." Many people blame their equipment and, indeed, there are many cases in which the equipment is to blame. However, I have found that the vast majority of cases are simple user errors. They often boil down to a lack of understanding of how the autofocus (AF) system works. This article will give you a better idea of focus and sharpness, and hopefully help you get photos you're happy with!

1. Adjust your diopters

What are mine, you ask? Your diopters - or your eyepieces. You will never know if a camera is well focused on a subject unless you can see for yourself what is in focus through the viewfinder eyepiece. On the side of the eyepiece (as shown below) there is a small wheel to adjust the focus of the eyepiece to suit your vision.

You can adjust the eyepiece to quite a large correction, but if you need even more correction, then interchangeable diopters in the range from -5 to +4 are available for DSLR / SLR cameras from many major manufacturers. No, this won't help your autofocus work better, but it will help you recognize when it misses and correct the situation with manual focus.

2. Understand your viewfinder

What the hell do all these things inside mean? At this point, you might want to get the instructions (remember that paper book that came with your camera?). Most common DSLR cameras has 9-11 focus points. The best of the best, professional cameras can have from 45 to 51 points (although in fact you can only choose 11-19, the rest of the points are optional).

There are two types of focus points: co-plane and intersection points. Single plane points only work on contrast lines that are directly perpendicular (90°) to their orientation. So, if you're looking through your viewfinder like the one above, you'll see that most of the dots are rectangular, some are oriented horizontally, some are oriented vertically.

Points of the same plane will only work perpendicular to their orientation. So - let's say you were shooting a tree - a vertical focus point wouldn't be able to find the edge of the tree trunk, but a horizontal one would. You can use this to your advantage when choosing a focus point that will lock onto the line you want and ignore those you don't want to focus on.

Cross point focus points will work with lines of contrast placed in any way. Most cameras have a single focusing intersection point in the center, surrounded by points on the same plane. Latest cameras today contain intersection points at all focal points.

Each focus point also has a specific sensitivity. Most require a lens with an aperture limit of at least f5.6 to even use autofocus. On most cameras, the surrounding AF points are just that sensitive, and the center point provides increased sensitivity if you use a lens with an aperture limit of at least f2.8.

So if you're working in low light conditions, you can achieve better autofocus by using the center focus point. Even if you don't use an f2.8 lens, or better yet, there are no light restrictions to favor the center point, it can still give a more accurate result because it is the intersection point.

When we look at the focus point rectangles, it's worth remembering that the real area of the sensor is 2-3 times larger than what is displayed. Keep this in mind as you focus. If you fix the focus on someone's bridge of the nose, remember that the person's eyes will also fall into the active area of the sensor. Autofocus will lock on to the eye rather than the bridge of the nose because the eye has more edge contrast than flat lighting on the nose. Often this may not matter, but if you are working at a very shallow depth of field, you will feel the difference in which area of the image is most sharp.

3. Lend a helping hand to your lens

Most autofocus systems have a certain amount of error or variance and can actually miss the point of optimum focus due to the mechanics and inertia of lens movement. You can minimize this effect by manually focusing the lens as close to the desired focus as possible, then letting the autofocus system finish focusing. Or, if this seems too difficult for you, at least let the autofocus make two attempts to achieve correct aiming. Half-press the shutter button to set the approximate focus, and then press again to fine-tune it.

The advantage of higher end lenses is that they allow full manual control even when autofocus is locked. Cheaper lenses do not allow manual focus adjustment after locking, although this good way make sure the focus is as perfect as it can be.

4. Find a good line

Autofocus systems work on contrasting lines, so they may struggle on non-contrasting subjects (eg cheek or forehead, white dress or black tuxedo, sand, monochrome walls, etc.). In areas like these, autofocus can go all day long and never lock. The approach is to find the "best line" - it could be the eyes, the lines between the contrasting shirt and suit, between heaven and earth, the doorway. Anything with contrast will help autofocus work better and faster.

Weak focus zone

Best Area to Focus

5. Don't use all-point focus mode

Unless you're in a terribly fast-paced situation that requires incredibly fast aiming, it's best to avoid all-point focus mode. This mode doesn't know what you want to focus on and is usually fixed to whatever is closest to the camera. There are situations in which this is exactly what is needed, but they are few and far between.

6. Focus and recompose - but do it the right way

I'm used to focusing and recomposing using the center focus point all the time. I lock the focus and then recompose the shot. I once read a few articles that said you shouldn't do this - that you should use the point closest to the area you want to focus on. Theoretically, this is justified by the fact that during the movement of the camera, due to the movement of the lenses and the change in the angle value, the distance between the subject and the lens also changes.

If you use the focus point directly on the subject and do not recompose the frame, then there will be no change in the distance between the subject and the lens, and therefore erroneous focusing. So, I decided to take some pictures to show you that it is - and it is not.

There was absolutely no advantage in using the nearest non-center point without changing the composition. In fact, focusing using the center point and recomposing was, indeed, more accurate in all cases except for one - macro. I took shots at all focal lengths from 17mm to 200mm and checked all distances from macro to 10 meters - with the same results.

Each test using the center focus point and recomposing the frame resulted in a sharper picture. Greater sharpness from using the center point and recomposing, less sharpness from using an outer focus point right on the subject. To clarify, the above theory is correct, in that you lose sharpness by moving the frame away from a fixed center point. What's not true is that using an outer point directly on the object will bring back sharpness - it won't.

I think there is a good chance that on my camera the center focus point is three times more sensitive than any of the other eight points, and it is this one that is most accurate. But so is the case with many cameras, with the exception of high-tech new models like the Canon 1Ds Mark III or Nikon D3X. Other possible the reason is that most lenses are sharpest in the center and lose sharpness towards the edges.

Here are three of the most typical examples of what I shot on two different cameras. An insert is an inscription on a scale of 100%.

Center focus point, no composition change. Lens 50mmf 1.8.

Lens 50mmf1.8. Central focus point. The camera is moved to the left after fixing the focus.

Lens 50mm f 1.8. Left focus point. Focus on the object.

What can I say - whether to switch the focus point or not, in my opinion, is a matter of time. But try it yourself, your result may differ.

A small note on macro - such shots should always be taken with a tripod and manual focusing, due to the extremely shallow depth of field and the proximity of the lens to the subject.

7. Use the correct focus mode

Most DSLR cameras have at least two similar focus modes. The first is "One Shot" (Canon) or "Single Servo" (Nikon). This mode assumes that the object is stationary. Focus locks, you get lighting confirmation on the internal display, and then you release the shutter. You will not be able to release the shutter if the focus is not locked.

The second type is “AI Servo” (Canon) and “Continuous Servo” (Nikon). This mode is suitable for shooting subjects in motion, including sports events, wildlife etc. The camera finds the subject using the focus point, and the focus will constantly change to keep up with the subject, but will never lock. The shutter button will work even if the focus is not perfect.

There are also other modes on some cameras, such as Canon's AI Focus, which are great when the subject is static but may start to move, as is the case with young children. Autofocus will lock on the subject, but if the subject moves, the camera will enter AI Servo mode to track it.

The third option, pre-focus, is for objects that are moving towards or away from you. The camera will try to predict the movement and give you an acceptable focus.

8. Don't change depth of field for good focus

Although using a larger depth of field with a smaller aperture can increase the "apparent" sharpness of an image, remember one thing: no matter what the depth of field is, there is only one point of focus. So always practice good focusing techniques no matter what depth of field you use.

9. Use a tripod or find a foothold

When we take a photo, we all unconsciously sway back and forth - in particular, leaning towards the subject with a heavy camera and lens kit. It `s naturally. Everyone has it to one degree or another. And if you're shooting with a very shallow depth of field, that small amount of distance you shift can have a big impact on the sharpness and the sharpness of focus you want. If you're using a 4" depth of field, a 2" offset can have a disastrous effect. So use a tripod.

Now I have to add, since I use a tripod myself - I hate them. They affect the way I work and, most of the time, the way I shoot. So, if you prefer to avoid using a tripod, at least take the time to practice your position. good photographer. One foot in front of the other, legs slightly bent, arms pressed to the sides, not dangling in space (remotes can come in handy here remote control), and the weight of the body is distributed centrally over the legs.

10. If still unsuccessful - use manual focus

I hear a deep sigh every time I offer this to photographers. They regularly state, "I shoot only in manual mode, never on automatic." But offer them one more time manual focus, and they will look at you as if you just offered them to sell their children. Manual focusing in most cases (assuming your diopters are set correctly) will achieve the best and most accurate result. Especially in this digital age, when it's so easy to see an image at 100% or even 200% magnification on our monitors.

In fact, if you look at the unofficial autofocus specs, you'll notice that they aren't very accurate. Here is the specification for "sharpness": An image is considered sharp if it appears sharp in print 6x9 from a distance of 10 inches. Yep, that's it. No 100% zooms, no 20x30 prints. Just this.

Today, a number of new cameras are being produced with a built-in Live View mode. This can be a useful tool for manual focusing. Turn on your Live View, zoom in on the subject/focus point and check the sharpness on the display. This doesn't work very well in my case, as I'm almost always in bright environments: deserts, beaches, etc. - but for some it will work just fine.

One note about the image above. I usually use it to show the manual focus switch, but the other switch is also of interest: "1.2m to infinity" and "3m to infinity". This switch is related to what I was talking about earlier: don't make your lens hunt for focus through as much space as possible. If you know you won't be focusing on anything closer than three meters, move the lever to the appropriate position and the lens won't have to wander around looking for focus. This can result in more accurate primary auto focus.

11. What should I focus on?

For close-up portraits, the consensus is, in general, worked out: the eyes. For other types of portraits, it's still the face, unless you intentionally want to focus on some other part of the body. Focus precisely where you want the viewer's eye to go.

Landscapes aren't always easy, but you still need to stick to the rule mentioned above. Do not bet on the fact that "this is a landscape with a wide viewing angle, focus on infinity." If you have a subject in the foreground, focus on it and let your depth of field bring the image into the background. If the object in the foreground is not in sharp focus, it is confusing, because in natural conditions we usually see objects that are closer rather than distant ones.

I can now work with focusing at "Hyper Focal Distance", but that's out of the scope of this tutorial. If you are interested in this topic, which is quite likely, use quick search in Google.

12. Is the subject in focus, but is it sharp?

Focus and sharpness are two different things. Explaining the concept of sharpness can take another lesson of its own, so I'll just point out a few useful points.

If an image is out of focus, you cannot bring it back into focus by sharpening it. You will only get a very sharp out-of-focus picture. Most RAW images need some sort of sharpening. Whether you're using Smart Sharpen, Un-sharp masking, or high pass filtering techniques, most RAW images benefit from sharpness. However, as I gradually started using higher and higher quality cameras, I saw less and less need for sharpening, and now I only use this tool in about 25% of my frames.

Remember also that sharpness depends on the final product. You won't sharpen in the same way on an image that goes to the web as you would on a 16x20 print. And with that in mind, if you intend to sell your photo through a stock agency, don't sharpen it at all. Most will tell you not to do this because you can't predict what the image will be used for and at what size.

On the left are images directly from the camera, unedited ("Straight Out of the Camera"), on the right - with added sharpness.

13. Consider exposure

Shutter speed is another setting that can lead to a lack of sharpness. Each person has a limit on the shutter speed at which he can shoot handheld on lenses with different focal lengths. Some people are more stable than others, but if you're shooting at a shutter speed that can't compensate for the movement (trembling) of your hands, your image will come out blurry. When it comes to standard and wide angle lenses, most people can shoot handheld with them consistently at around 1/30-1/60 of a second.

Larger telephoto lenses require much faster shutter speeds. General rule, which people start with: "1 to the focal length of the lens". So, if you have a 200mm lens, shoot at 1/200th of a second, and start from that level to understand your further possibilities. Personally, I shake like California in worst days, so I usually shoot at faster shutter speeds. It also depends on how far away you are from your subject, as the farther you are, the more noticeable the movement.

If the subject is moving, keeping the camera stable or on a tripod won't help - you'll still need to choose a satisfactory shutter speed in order to stop the action. Most start at 1/250, but it depends on how fast the object is moving. The requirements also vary depending on whether you are shooting in a static position or following the subject. If the latter, you can choose a slower shutter speed and also get some cool effects. This will allow you to show movement in the background, but will freeze the object itself.

Image stabilization systems on lenses allow you to shoot handheld at faster shutter speeds (up to 3 stops), but will not "stop" movement any better than a lens without an image stabilization system. You can only capture the action with a shutter speed (or high-speed flash).

Image not out of focus. The shutter speed is too long.

14. Choose the right exposure

correct exposure and good lighting(the essence of all photography) is the key to good focus and sharpness. While sharpness is determined by the line of contrast, if you underexposed the frame or shot in dim light, the image will not be sharp even if all other parameters of good focus are met.

15. I did it all. I'm still out of focus!

There is a small chance that something is really wrong with your hardware. Third-party lenses are sometimes not very well designed, and therefore will not always work perfectly with branded cameras. Some work great, others don't. But sometimes even branded lenses are not made perfectly.

Cameras such as the Canon 50D and 1D/Ds Mark III have excellent front and back focus adjustments for over 20 different lenses, so if you know one lens is perfectly focused in front of your subject all the time, you can adjust the camera. to fix it. If this option is not available, you need to determine if your lens, or both lens and camera, needs repair.

Here's a test you can do at home to see if it's you or the camera. Find a ruler and place it on the table away from the camera. Put the camera on a tripod and open the aperture as wide as possible. Take a picture of the ruler at a 45-degree angle, focusing on a specific mark - in this example, the six.

If this is the mark that you will see as clearly as possible when you open the image, then everything is in order with your equipment - get back to working on your technique! If the sharpest point is before or after this mark, then you will know that this is a hardware problem and should be taken to service.

16. Conclusion

I covered a lot of questions in this tutorial - great that you read to the end! It seems to me that good focus and sharpness are two of the most important technical parameters that must be preserved in an image. This can make the difference between what looks professional and what looks like amateur work (and we all want to look like professionals, whether we are or not).

Please feel free to leave your opinion in the comments - have you ever had problems with focus and sharpness?

One of the significant problems for many beginners, and even quite experienced photographers, is achieving the desired sharpness of the resulting images. "Get in focus" sounds very simple, but in practice this action can be a little more difficult.

On the one hand, there are many ways to get a photo in focus. What is the best method to choose and how exactly to use it to achieve the desired results? Let's take a look at some of the most common and effective ways camera focus.

One-Shot AF

One of the most simple ways The focus of the camera is to use One-Shot AF, which in most cases is the default setting and one of the most effective ways to photograph.

In single frame mode, you simply aim the camera at the subject and press the shutter button halfway.

This locks focus on the subject, allowing you to recompose the image if necessary without losing focus. This technique is called focus and recomposition.

For example, in the image above, if you want the bridge to be in focus, you need to position the center AF point on the bridge and press the shutter button halfway.

You will then compose the shot as you see above and press the shutter button all the way down to take the photo. As a result, you will get the subject in focus even if you have recomposed the photo.

This option is good for landscape photography or shooting stationary subjects.

Continuous autofocus

Obviously, there are no perfectly still objects, so you need a focusing tool that allows you to track moving objects while keeping them in focus.

In this case, continuous autofocus can come to the rescue. All you have to do is capture the subject with the viewfinder, press the shutter button halfway, and follow the subject as it moves while holding the shutter button halfway down. This will continuously adjust the focus (hence the name).

Most entry-level cameras require you to use the center point for continuous AF, but if your camera is higher-end, you can determine which AF point is used to track a moving subject.

Naturally, this type of focus is best for shooting, for example, wildlife or where you need to quickly adjust the focus.

Face detection autofocus

Not all cameras have face-detection autofocus, but if it does, it's a valuable tool for portraiture. It uses algorithms to recognize shapes that resemble human faces.

In Live View mode, you can see the focus on the face as you work as a frame around the face.

All you have to do is press the shutter button halfway to indicate the area you want focus on and then take the picture.

Focus point selection

Regardless of which AF mode you use, you need to have an active AF point on your subject. Otherwise, the object will not be sharp.

Generally, there are two ways to select an active AF point: select it yourself or automatically using the camera. Most cameras these days are pretty good at picking the right AF point for most situations. But it's still not always perfect.

In situations where time is of the essence, such as portraiture or landscape photography, try choosing your own AF point. See your camera's User Manual if you don't know how to do this.

However, be aware that your lens will focus best when using the center AF point. If you use a different focus point, the image may not be sharp enough.

Back button focus

Another way to get the image in focus is to use back button focus. Depending on the specific camera, you may have an autofocus button on the back of the body that you can press all the way down to focus on the subject.

This is beneficial for a number of reasons, including preventing you from accidentally pressing the shutter button and therefore taking a photo before you (or the camera) were ready. When shooting moving or multiple subjects, back button focusing also allows you to focus on your main subject. In other words, by releasing the autofocus button, you are preventing the camera from focusing on the new subject, and you can still take photos with focus on your main subject.

Manual focus

The manual focus process may vary slightly depending on the specific camera or lens, but the following steps are basically standard:

find the AF-MF switch on the lens and move it to the MF position
rotate the focus ring on the lens until you see that the desired subject is sharp
using Live View, zoom in on the subject to check its sharpness. Adjust with the focus ring if necessary.

That's all!

Manual focusing can take a little longer than auto focusing, but it works better in a wide variety of situations, such as macro photography when you're shooting through something (say, using a plant in the foreground to frame a subject in the background), subjects in crowded places (street scenes), and in low light situations. In other words, in situations where auto focus "resists", don't be afraid to switch to manual.

hyperfocal distance

A more complex and technical method for obtaining focus is to calculate the hyperfocal distance. Basically, it's that you have to use the depth of field calculations for the lens you're using to find the closest point in the picture where you can still get acceptable sharpness.

Finding this point will allow you to focus on the spot that will give you the best depth of field and maximize the area of field in your photo.

There are several ways to determine hyperfocal distance, but the simplest among them are the following:

focus on one third of the bottom of the frame. Since the depth of field extends to about twice the focal point, focusing on that third will help you maximize the depth of field;
a smartphone app such as HyperFocal Pro for Android (shown above) or Digital DOF for iOS devices can be used to save you the trouble of doing any math.

If you landscape photographer, using the hyperfocal distance will be especially useful for you.

Focus stacking

The final method, which we will cover in this article, of obtaining perfect focus in photographs is the use of the Focus stacking method, which is achieved through post-processing.

Basically, you take several different photos, each with a different focus point (i.e. focus on the foreground, middle, and background) and merge them together into one image in post-processing. The resulting composite photo will be sharp from foreground to background.

This method is especially useful for macro and still life photography, and is also good for landscape photography.

A word of caution about the Focus stacking method: there can't be any movement in the snapshot.

This is because you are taking multiple exposures at different times, so if something in the frame is in motion (such as a tree due to wind) it will cause ghosting. Anything that moves in the photo will be blurry.

Another complication with this method is that you need to adjust the focus for each shot without disturbing the camera position. Otherwise, the frames used will not match perfectly in post-processing.

So, now you have a number of methods that will help you adjust the focus on the subjects you are shooting. It will take time to master them. However, it's definitely worth it. Take action!

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