Camera focusing: Using manual and automatic mode. Autofocus modes

The most common complaints I hear from most photographers at any level are these types of complaints: “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 come down to a lack of understanding of how the autofocus (AF) system works. This article will give you a better understanding of focus and sharpness, and hopefully help you get photos you're happy with!

1. Adjust your dioptres

You ask, my what? Your diopters - or your eyepieces. You'll never know if your camera is focusing well on a subject if you can't see what's in focus through the viewfinder eyepiece yourself. On the side of the eyepiece (as shown below) there is a small wheel for adjusting the focus of the eyepiece to suit your vision.

You can adjust the eyepiece to a fairly large correction, but if you need even greater correction, interchangeable diopters ranging from -5 to +4 are available for DSLR/SLR cameras from many major manufacturers. No, this will not help your autofocus work better, but it will help you understand when it misses and correct the situation using manual focusing.

2. Understand your viewfinder

What the hell do all those things inside mean? At this point, you might want to get the instructions (remember that little paper book that came with your camera?). Most regular DSLR cameras have 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 remaining points are additional).

There are two types of focus points: coplanar and intersection points. Same plane points only work on lines of contrast directly perpendicular (90°) to their orientation. So, if you look through your viewfinder like the one pictured above, you will see that most of the dots are rectangular, some are oriented horizontally, some are oriented vertically.

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

Cross point focus points will work with lines of contrast placed in any way. Most cameras have one focal 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 this 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 are working in low light conditions, you can achieve better autofocus by using the center focusing point. Even if you don't use an f2.8 lens, or better yet, there are no light restrictions that favor the center point, it can still produce a more accurate result because it is the intersection point.

When we look at focus point rectangles, it's worth remembering that the actual sensor area is 2-3 times larger than what is displayed. Keep this in mind as you focus. If you are focusing on the bridge of someone's nose, remember that the person's eyes will also fall within the effective sensor area. Autofocus is more likely to lock onto the eye than the bridge of the nose because the eye has more contrast around the edges 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 sharpest.

3. Give your lens a helping hand

Most autofocus systems have a certain amount of error or deviation and can actually miss the optimal focus point due to the mechanics and inertia of the lens movement. You can minimize this effect by manually focusing the lens close to the desired focus and then letting the autofocus system finish focusing. Or, if that seems like too much of a hassle, at least give the autofocus two tries to get it right. Press the shutter button halfway to set the approximate focus, and then press again to fine-tune it.

The advantage of lenses is more high level is that they allow full manual control, even when autofocus is locked. Cheaper lenses do not allow you to adjust focus manually after locking, although this good way make sure the trick is as perfect as it can be.

4. Find a good line

Autofocus systems work on contrast lines, so they may have difficulty on low-contrast objects (for example, a cheek or forehead, a white dress or a black tuxedo, sand, plain walls, etc.). On areas like these, autofocus can be aimed all day and never lock. The approach is to find the "best line" - this could be the eyes, the lines between a contrasting shirt and suit, between heaven and earth, a doorway. Anything that has contrast will help autofocus work better and faster.

Low focus area

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 focusing mode. This mode doesn't know what you want to focus on and usually locks onto 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 change the composition - but do it correctly

I'm used to focusing and changing composition using the center focusing point all the time. I fix the focus and then recompose the shot. I once read some articles that said that 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 when the camera is moved, due to the movement of the lenses and the change in the angle, the distance between the subject and the lens also changes.

If you use the focusing point immediately aimed at the object and do not recompose the frame, then there will be no change in the distance between the object and the lens, and therefore, erroneous focusing. So, I decided to take some pictures to show you that this is true - and that it is not.

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

Each test using a central focusing point and recomposing the frame resulted in a sharper image. Greater sharpness comes from using the center point and recomposing, less sharpness from using the outer focus point directly on the subject. To clarify, the theory above is correct in that you lose sharpness by moving the frame away from the fixed center point. What is not true is that using an external point directly on the object will return sharpness - it will not.

I think there's a good chance that on my camera, the center focus point is three times more sensitive than any of the other eight points, and is the most accurate. But this 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. The inset is an inscription at 100% scale.

Central focus point, without changing composition. Lens 50mmf 1.8.

Lens 50mmf1.8. Central focal point. The camera is moved to the left after focusing.

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

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

A quick note on macro - such shots should always be shot 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). In this mode, the object is assumed to be stationary. Focus locks, you get lighting confirmation on the internal display, and then release the shutter. You won't 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 designed for shooting subjects in motion, including sports events, wildlife etc. The camera finds the subject using the focusing point, and the focus will change constantly to keep up with the subject, but it will never lock. The shutter button will work even if the focus is not perfect.

Some cameras also have other modes, such as Canon's “AI Focus”, which are good if the subject is static but may start to move, as is the case with small children. Autofocus will lock onto the subject, but if the subject moves, the camera will go into AI Servo mode to track it.

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

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

While using a greater depth of field with a smaller aperture can improve the "apparent" sharpness of an image, remember one thing: no matter what the depth of field, there is only one point of focus. So always practice good focusing techniques, regardless of the depth of field used.

9. Use a tripod or find support

When we take a photograph, we all unconsciously sway back and forth - especially leaning towards a subject with a heavy camera and lens set. It `s naturally. Everyone experiences this to one degree or another. And if you're shooting with a very shallow depth of field, that little distance you move can have a big impact on the sharpness and focus clarity you want. If you are using a depth of field of 4 inches, a deviation of 2 can have a disastrous effect. So, use a tripod.

Now I have to add, since I use a tripod myself - I hate them. They influence the way I work and most of the time the way I shoot. So, if you'd rather avoid using a tripod, at least take the time to practice the position good photographer. One foot in front of the other, legs slightly bent, arms tucked to your sides, not flopping around (this is where remote controls can come in handy), and body weight distributed centrally over your legs.

10. If still unsuccessful, use manual focus

I hear a deep sigh every time I suggest this to photographers. They regularly claim: “I only shoot in manual mode, never in automatic mode.” But offer them a manual one again focusing, and they will look at you as if you just offered to sell them your children. Manual focusing will in most cases (assuming your diopters are set correctly) will achieve the best and most accurate results. Especially in this digital age, when it is so easy to view 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 on the print 6x9 from 10 inches away. Yeah, 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 when focusing manually. Turn on your Live View, zoom in on your subject/focus point, and check the sharpness on the display. This doesn't work particularly well in my case, since I'm almost always in brightly lit 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 lever, but another switch is also of interest: "1.2m to infinity" and "3m to infinity". This switch relates to what I was talking about earlier: don't force your lens to hunt for focus through every possible space. 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 trying to find focus. This can result in more accurate primary autofocus.

11. What should I focus on?

For portraits close-up A common opinion has generally been reached: the eyes. For other types of portraits, it's still the face, unless you deliberately want to focus on some other part of the body. Place precise focus where you want the viewer's eyes to go.

It's not always that simple in landscapes, but you should still stick to the rule mentioned above. Don't bet on "this is a wide-angle, infinity-focus landscape." If you have a subject in the foreground, focus on it and let your depth of field bring the image into the background. If an object in the foreground is not in sharp focus, it is confusing because we naturally tend to see close objects in sharper focus rather than far ones.

Now I can work with focusing at "Hyper Focal Distance", but that is beyond the scope of this tutorial. If you are interested in this topic, which is likely, do a quick Google search.

12. The subject is in focus, but is it sharp?

Focus and sharpness are two different things. Explaining the concept of sharpness could take another separate lesson, so I'll just make a few useful points.

If an image is out of focus, you cannot bring it back into focus by adding sharpness. You'll just end up with a very sharp, out-of-focus picture. Most RAW images need some kind of sharpening added. Whether you use Smart Sharpen, Un-sharp mask, or high-pass filtering techniques, most RAW images benefit from sharpness. However, while I gradually began to use cameras more and more High Quality, I began to see less and less need for sharpening, and now only use this tool in about 25% of my shots.

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

On the left are images straight out of the camera, unedited (English: “Straight Out of the Camera”), on the right - with added sharpening.

13. Consider the shutter speed

Shutter speed is another parameter that can cause 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 consistent than others, but if you shoot at a shutter speed that can't compensate for the movement (shake) of your hands, your image will come out blurry. When it comes to standard and wide-angle lenses, most people can shoot consistently handheld at about 1/30-1/60th of a second.

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

If the subject is moving, holding the camera steady or on a tripod won't help - you'll still need to select a satisfactory shutter speed to freeze the action. Most people start with 1/250, but this depends on how fast the object is moving. Requirements also vary depending on whether you're shooting in a static position or following your subject. If the latter, you can choose a slower shutter speed and get some interesting effects too. This will allow you to show movement in the background, but will capture the subject 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 using shutter speed (or high-speed flash).

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

14. Choose the correct exposure

Correct exposure and good lighting (the essence of all photography) are 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 lighting, the image will not be sharp even if all the other parameters of good focus are met.

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

There is a small chance that there is actually something wrong with your hardware. Lenses from third party companies are sometimes not very well designed, and therefore they will not always function perfectly with branded cameras. Some work great, others don't. But sometimes even branded lenses are not made perfectly.

Cameras like 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 will need to determine whether your lens, or both the lens and the camera, need 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. Place your camera on a tripod and open the aperture as wide as possible. Take a photo 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 equipment! If the sharpest point is before or behind this mark, then you will know that it is a hardware problem and should be taken in for service.

16. Conclusion

I covered a ton of topics in this lesson - I'm glad you read to the end! It seems to me that good focus and sharpness are two of the most important technical parameters, which need to be saved in the image. This can make the difference between shots that look professional and those that look like amateur work (and we all want to look like professionals, whether we are or not).

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

Focus Modes

The focus mode that everyone usually works in is One Shot AF. It suits any static subject, and sometimes even slowly moving objects. When you shoot in One Shot AF mode, you frame your scene using the viewfinder and press the shutter button halfway. The autofocus system turns on and the lens focuses directly on the main subject. At this stage, a green light lights up, confirming focus, and you can also hear a sound confirmation.

Once the camera has established a focus point, it locks it. If you keep your finger on the shutter button, the focus will not change - even if you move the camera. This useful feature is called "Focus Lock". It allows you to first focus on a point outside the scene, then rotate the camera and compose. For example, imagine that you are photographing a landscape. The camera may want to focus on the furthest hills, but you want to increase the depth of field by focusing on a point that is closer to the camera. All you need to do is tilt the camera down a little so that this point comes into view. Now press the shutter button halfway, make sure the camera has focused (the green confirmation light will light up), and keep the shutter button halfway pressed while you compose your landscape.

One Shot AF mode has another useful feature. The camera will not allow you to take a picture if the lens is not focused. If the focus confirmation signal blinks, it means that the lens was unable to focus and nothing will happen after pressing the shutter button completely.

Shutter button

Your EOS camera's shutter button is actually a two-position electrical switch. Partially pressing the button activates the first switch (Canon calls it SW-1). After the first press, the autofocus and exposure metering systems are turned on. In low light conditions (depending on the selected shooting mode), the built-in flash may pop up. To help the camera focus in low-light conditions, the AF-assist lamp may light. Fully pressing the shutter button activates the second switch (SW-2) and starts the following chain of actions:

the mirror inside the camera is raised up so that the light flux can reach the back of the camera
the shutter mechanism starts - the curtains open and the film (or digital sensor) begins to receive light flux
if the built-in flash is raised or an external Speedlite is installed and turned on on the camera, the flash fires
the mirror returns to its previous position
the shutter returns to its original position and is ready for the next exposure

AI Servo AF mode

AI Servo AF mode is essentially the same as One Shot AF, only without focus locking. The lens automatically refocuses whenever the distance between the camera and the subject changes. This feature is very useful when photographing moving objects. This mode is most often used in sports photography. However, it must be used with caution. In this mode, you can take a shot even when the lens has not yet focused or has failed to focus. In addition, if any moving object appears between the camera and the subject, the lens can focus on the object located closer to the camera. All of this can result in out-of-focus images.

In AI Servo AF mode, the green focus confirmation light will not light up, and you will not hear a confirmation beep (even if it is turned on). However, in both One Shot AF and AI Servo AF modes, the green light will blink if the camera is unable to focus on the subject.

There is a slight delay between the lens focusing and the shutter releasing. Although it is measured in fractions of a second, it can be taken into account when photographing fast moving objects - for example, a racing car at a speed of 160 km/h travels approximately 4.5 m in 1/10 s. This means that while the car might be in focus when the shutter button is pressed, it may not be in focus when the shutter itself opens.

Many EOS cameras solve this problem with predictive focusing technology. The camera measures the distance to the subject each time the lens refocuses. By analyzing this data, the camera can calculate the speed and direction of the object's movement. It then extrapolates the information received to determine where the subject will be when the shutter is released. Next, the camera refocuses the lens to the calculated distance so that the subject is in focus at the time of exposure. Predictive focus mode is activated automatically when needed.

Custom function

In One Shot AF mode, partially pressing the shutter button activates the autofocus system. Once the camera has focused, it will maintain that focus as long as you continue to press the shutter button. This means that you can focus on a random point, and then you can rotate the camera and compose the scene without changing focus.

Focus locking is effective when the main subject is not well lit or has insufficient contrast for the lens to focus on it. In this case, you focus on any other object that is at the same distance from the camera as the main subject.

Focus lock mode is not available in AI Servo AF - the lens will constantly refocus as you move the camera. However, setting CF 4-2 on the EOS 1N and 1V allows you to pause auto refocus in AI Servo AF by pressing the AE Lock button.

AI Focus Mode

The third focusing mode - AI Focus - is actually a combination of the first two. Most of the time the camera is in One Shot AF mode, but if the focus sensor detects that the main subject is moving, the camera automatically switches to AI Servo AF mode and begins tracking the subject.

How does the camera determine that the subject is moving? As soon as we press the shutter button halfway, the focus sensor begins to work constantly. If the focusing distance changes, the camera detects that the subject is moving - and can determine the speed of movement. As soon as this speed exceeds a certain threshold, the camera switches to AI Servo AF mode.

Typically, AI Focus mode is used on inexpensive EOS models - it is assumed that this mode is used by people with little experience in photography. With AI Focus, you can focus on the story while the camera chooses the best shooting mode for you.

On some models, different autofocus modes are set by the camera based on the selected shooting mode - for example, One Shot for landscape mode and AI Servo for sports mode.

All EF lenses support autofocus. However, there are some non-EF lenses in the EOS system that need to be manually focused. These are lenses from the Tilt&Shift series - TS-E 24mm/45mm/90mm, as well as the MP-E65 f/2.8 1-5x Macro lens.

Autofocus modes

Camera	One Shot AF	AI Servo AF	AI Focus	Manual
EOS 1
EOS 1N
EOS 1N RS		(·)
EOS 1V
EOS 10
EOS 100
EOS 1000/F/N/FN
E0S 3
EOS 30/33
EOS 300
EOS 300V
EOS 3000
EOS 3000N
EOS 5
EOS 50/50E
EOS 500
EOS 500N
EOS 5000
EOS 600
EOS 620
EOS 650
EOS 700
EOS 750
EOS 850
EOS RT		(·)
EOS IX
EOS IX 7
EOS 1D
EOS 1Ds
EOS 10D
EOS D2000
EOS D30
EOS D60
EOS DCS 3

This table shows the autofocus modes of EOS cameras. You can set the mode yourself [·], or the camera itself sets the autofocus mode depending on the selected shooting mode [o]. All cameras except the EOS 650 and 620 have predictive focusing in AI Servo AF mode.

(·) - AI Servo AF is not available when the EOS 1N RS is set to RS mode (similarly when the EOS RT is set to RT mode).

Selecting an autofocus mode

It's always useful to know what the camera does - in this table you will find all the necessary information.

Selecting an autofocus mode is only possible in the creative zone (P, Tv, Av, M, DEP), and only on some cameras. In other shooting modes, the camera makes the choice itself:

Camera	Machine	Portrait	Scenery	Macro	Sport	Night
EOS 1
EOS 1N
EOS 1V
EOS 10
EOS 100
EOS 1000/F/N/FN
EOS 3
EOS 30/33
EOS 300
EOS 300V
EOS 3000
EOS 3000N
EOS 5
EOS 50/50E
EOS 500
EOS 500N
EOS 5000
EOS 600
EOS 620/650
EOS 700
EOS 750/850
EOS RT
EOS IX
EOS IX 7
EOS 1D
EOS 1Ds
EOS 10D
EOS D2000
EOS D30
EOS D60
EOS DCS 3

U - the user selects the mode himself
OS - One Shot AF Mode
AF - AI Focus AF Mode
AS - AI Servo AF Mode

Manual focus

Finally, there is a manual focus mode. It can be used with any EOS camera, but is not a function of the camera, but of the lens. Look on the side of the lens, next to the red dot - you will see a switch with two positions - "AF" and "M". Switch it to the "M" position and the lens will no longer focus automatically. Instead, it will focus according to how you rotate the focus ring on the lens itself. The only EF lens without manual focus is the EF 35-80mm f/4-5.6 PZ - this lens with a focusing motor (Power Zoom) was sold with the EOS 700.

All EF series lenses are designed with autofocus in mind. If you've used older FD lenses, you might find manual focusing on EF lenses not as smooth as full-on focusing. manual lenses F.D. Additionally, from infinity to the closest distance, the focusing ring scrolls quite quickly, making precise focusing difficult in some cases. However, it depends on the specific lens.

In general, why do you need manual focusing on autofocus lenses? There are some situations where the autofocus system will be quite difficult to cope with: scenes with low contrast - for example, landscapes in fog or the surface of the sea; low light scenes (actually special case plot with low contrast); extremely bright reflections from water, ice or metal; Subjects that move too quickly to be automatically focused on; scenes in which the main subject is not closest to the camera (for example, an animal in a cage behind bars).

If the main subject is close to the camera, the camera's built-in focus assist system (or a more powerful Speedlite flash) can help, but it only works if the subject is not very far away.

In all such situations the best way out- focusing the lens manually.

Many USM lenses allow you to focus manually immediately after autofocus has been achieved - without the need to constantly switch between manual and auto focus modes. This feature is called Full-Time Manual Focusing (FTMF). This is particularly useful when using telephoto lenses to make final adjustments to focus just before shooting. You can check if your lens has this feature by turning the ring immediately after autofocusing has finished.

How to choose autofocus mode?

Autofocus mode is selectable only in the creative zone (P,Tv,Av,DEP,M). In fully automatic mode (green square) and PIC modes, the camera itself sets the autofocus mode (see table). All you have to do is make sure that the lens is mounted correctly on the camera and is in autofocus mode ("AF").

The EOS 1, 600, 620 and 650 cameras display "M.Focus" when the lens is switched to manual focus mode; On other models, switching to manual mode is not displayed.

After autofocusing, you can lock the focusing distance by setting the lens to "M" mode. This will allow you to remove your finger from the shutter button, compose, and shoot at the original focusing distance.

EOS 1, 1N, 1V, 1D, 1Ds, D2000, DCS 3
Press the AF button at the top left of the camera and at the same time rotate the option wheel until “One Shot” or “AI Servo” is displayed in the top right corner of the LCD.

EOS 10
Press the yellow AF button on the back of the camera and at the same time rotate the option wheel until “One Shot” or “AI Servo” is displayed in the upper right corner of the LCD.

EOS D30, D60
Press the AF button at the top right of the camera and at the same time rotate the option wheel until “One Shot” or “AI Servo” is displayed in the upper right corner of the LCD.

EOS 10D
Press the AF button at the top right of the camera and simultaneously rotate the option wheel until “One Shot” or “AI Servo” is displayed in the lower right corner of the LCD.

EOS 1000/F, 1000/FN, 300, 300V, 3000, 3000N, 500N, 5000, 700, 750, 850, IX7
The autofocus mode is set automatically by the camera depending on the shooting mode.

EOS 30, 33, 50, 50E
Switch the AF mode dial to "One Shot", "AI Focus" or "AI Servo".

EOS 5
Press the AF mode button on the back of the camera. Rotate the Option Wheel until the LCD displays “One Shot,” “AI Focus,” or “AI Servo.” If you release the AF mode button, the selected mode will remain active for 6 seconds.

EOS 600, 620, 650, RT, IX
Press the AF mode button located under the flap on the back of the camera. Rotate the option dial until the LCD displays “One Shot,” “AI Focus,” or “AI Servo” (just “Servo” on the EOS 620 and 650).

Photos - David Hay, Paul Exton

source eos.nmi.ru 2002-2006 Alexander Zhavoronkov

Any newbie to photography, especially one armed with a low-end camera, will very quickly notice that the focal point in his photographs “moves” to completely different areas of the frame.

Yes, yes, the automatic DSLR decided that “that little flower over there” is a higher priority for the frame than the face of your not entirely sober friend. I can't disagree with your camera, but that doesn't change the fact that the camera's automation was wrong.

Many people mistakenly perceive the movement of the focal point to another place as a blurry photograph. “I wanted to take a picture of a portrait, but here everything is blurry”: is this familiar?!

However, if you look closely at this photo, you will see that the focal point is, say, on the carpet behind.

The eternal question arises: why did this happen and how to photograph so that it does not happen again?!

First, you need to understand and understand the principle of automatic focusing of a DSLR: in fully automatic focusing mode, your DSLR will select those points that have the most contrast.

For example: A groom in a black and white suit will be prioritized by the SLR camera automation over a bride in white standing a meter away from him. Accordingly, by giving the choice of focus point to the camera itself, you risk getting a clear photograph of the groom, while wanting to focus only on the bride.

How to avoid “incorrect” autofocus operation?!

There is only one recipe, it has been tested and beginning photographers should trust it completely, even on younger models of SLR cameras.

Never use automatic focus point selection. Switch the camera to manual focus point setting mode and set that point. Get used to switching these points when constructing a frame, which will subsequently give your photo a touch of artistry. Especially if you also learn to operate with depth of field.

Look at the photo at the beginning of the article, it was taken when setting the focus point manually on a bunch of leaves, which you observe in the field of focus and setting a shallow depth of field.

What did this photo give me?!

By setting a small aperture, I was able to get blurry the background, which made it possible to emphasize the foreground
Manually selecting the focus point aimed at the leaves prevented it from “going away” into a brightly lit and contrasting background with a spot of sunlight, which would inevitably happen with automatic focusing mode and I would get a photo with a blurred foreground and a sharp background, which I would not be necessary at all.

What does it take to accurately autofocus a DSLR?!

To accurately focus on exactly the objects you want to shoot, it is enough to fulfill two conditions:

The object must be in contrast to other objects or surroundings
You must use manual camera focus point selection

All this will allow you to focus the camera exactly in those areas of the frame that you want to capture.

Problems with focusing on younger DSLR models

However, the camera may miss autofocus, even with manual selection, not because of your lack of skill. With a completely functional DSLR, such nuances are possible, as it turns out.

There are two terms that describe a camera's autofocus miss:

Back focus / Back focus
Front focus / Front focus

As the names suggest, in the first case, the camera “moves” the focus point behind the subject. In the second, it places the focus point in front of the subject.

How much the DSLR will “undershoot” or “overshoot” depends on the factory settings and the Chinese person who assembled your device.

To fully understand this moment, I’ll tell you a little story:

It was quite a long time ago when I just bought myself a Canon 1000D DSLR. For a long time I could not understand that no matter what I did, the output of sharp photos taken on a beautiful summer day was very small. Only a couple out of ten could be called sharp, and even then with a stretch.

This is probably where I learned about back focus and front focus.

After reading the warranty card, I took my DSLR to service center for free adjustment/tuning/checking.

Afterwards, when I picked up the camera from the service, I asked the technicians what happened to it. The answer amazed me. The master said that both the lens and the DSLR had terrible frontal tricks. Both had to be configured. This is not a common case, but it cannot be said that it is rare either.

That is, the entire camera + lens system was not adjusted, neither to each other, nor to itself. After the service, to the latter’s credit, the quality of autofocus improved greatly, which led to the appearance of normal photographs.

So, the vaunted Japanese quality was not supported on younger models of DSLRs in my case. It was around then that I fell out of love with Canon.

With this, I end my lecture and wish you the final conquest of the autofocus of your DSLR.

To understand which autofocus mode to choose, you must first understand what you are photographing. Autofocus modes and settings on all cameras are approximately the same. They may have different names and be controlled differently, but the principle is the same everywhere. So what is autofocus?

First, make sure that autofocus is turned on. On advanced cameras (Nikon / /D7000 / D7100) there is a separate switch on which there is M mode (manual focus) and some other modes - different autofocuses, or just AF.

M (Manual) mode works the same way cameras worked in the 50s, that is, without autofocus. If you don't have such a switch, then the autofocus modes on your camera are controlled through the menu.

In addition, autofocus lenses with a built-in motor (AF-S) also have an autofocus switch, often marked M/A - M. Make sure that the lens is not in manual mode. Do not confuse the AF-S lens type with the AF-S autofocus mode, they are different things, although they are called the same.

Autofocus modes are as follows:

AF-A (Auto). Automatic mode, in which the camera decides for you how to focus. If you don't know exactly which mode you need, choose automatic mode.

AF-S (Single). Mode for static scenes. In this mode, the camera focuses once when you press the shutter button halfway, and that's it. The camera no longer focuses until you release the button. Great option for landscapes and portraits.

AF-C (Continuous). Tracking mode, when the camera constantly monitors the subject and adjusts autofocus continuously until you release the shutter button. It turns on when you press the shutter button halfway. This mode is essential when photographing wildlife, sporting events, and fast-moving children.

In the Custom Settings Menu in the Autofocus section you can find AF-S/AF-C priority selection.

Release- this triggers the shutter immediately, even if the image is completely out of focus. I can hardly remember ever getting sharp shots in this mode.

Focus- the shutter only fires when the image is strictly in focus. It's very slow and you risk missing a shot.

I recommend value Release+focus for AF-C, it's somewhere in between. Even if the first frame is out of focus, the next ones will be significantly better when shooting continuously. In this case, you will not lose the first frame, although it will be a little blurry. Focus is good for AF-S because nothing moves in the frame.

In addition, you still have to choose the type of autofocus area.

Nikon usually offers three options:

Conventionally, areas can be divided into two types:

Multiple sensors (AF-Area). Information about focus comes not only from the sensor you have selected, but also from the points surrounding it, and the surrounding sensors are not highlighted in any way. For example, on the Nikon D7000 you can select a zone of 9, 21 or 39 points. Typically, the faster something moves in the frame, the larger the area required. To be honest, I don’t use these zones, I prefer 3D tracking.

3D tracking. This mode may be present on some models along with a white rectangle and crosshair, on other models it may be somewhere else, for example, when choosing the size of the autofocus area. As the name suggests, this is a tracking mode, and when tracking, not only the distance to the object is taken into account, but also the color. You select a focus point, autofocus clings to what is under this sensor, and then begins to follow it if the subject moves or you turn the camera.

The fundamental difference between AF-Area and 3D tracking is that in the first case, the camera focuses on what falls within the selected autofocus zone, and in the second case, the camera itself moves the zone behind the object, switching autofocus sensors. Therefore, in 3D mode it is very convenient to focus on something specific, then move the camera to frame it differently, but autofocus will still focus on what it was initially aimed at. This differs from the AF-S mode in that AF-S is not aware if the object moved further or closer during framing, or even flew out the window.

Additionally, 3D tracking can even replace single focus point selection. Instead of going through the points with the selector until you get to the one you want, you can simply visit the center one in 3D mode and then frame it as needed, while the camera will keep focus on the subject, moving the focus point, switching autofocus sensors. At the same time, the subject will not be able to escape from autofocus.

Keep autofocus in auto mode (AF-A, white rectangle), this mode does a great job in most situations without your help. If the autofocus performance does not suit you in any particular case, then start thoughtful adjustments.

That's all autofocus is.

How to tame autofocus

The camera's focusing system is designed to help you take sharp, and therefore high-quality, pictures. You can adjust the sharpness manually or leave it to the camera's automation. Your choice will most likely be determined by your shooting situation and creative intentions.

In fact, the autofocus of modern cameras copes “excellently” with most scenes. However, you should not think that the camera will do everything itself. There are a number of nuances, only after mastering which you will be able to “tame” autofocus and get the kind of shots that you would like.

Auto Focus Modes

To get started with autofocus, first turn it on. In a number of cameras there is a special switch for this, designated “AF/M”. With it, you select manual (“M”) or automatic (“AF”) focusing. If such a switch is not found on the camera or lens, then the autofocus mode is activated using the menu.

Modern DSLR cameras have several autofocus modes. By choosing a mode, you determine exactly how your lens will focus. The accuracy of the automation and, ultimately, the quality of your image will depend on the correct choice.

The main autofocus modes that every DSLR camera has are single-frame focusing (also called spot, single, final or single) and tracking focusing (continuous). You need to select the mode you need in the camera settings.

You should also know that by default, single focus mode operates in focus priority (i.e., the shutter will fire only after focusing), and focus tracking mode operates in release priority (i.e., the camera will take the photo immediately after you press the shutter button, regardless of focus). You can change these settings at your discretion.

Single-shot autofocus in cells different manufacturers may be denoted as

Single-frame focusing is used for static scenes (such as landscapes, portraits or product photography). Before you take a photo, you must make sure that the camera is fully focused. Automation will notify you about this using sound signal and changing the backlight in the focus area. If the subject is moving, the camera may make a mistake - the subject will move out of focus. Therefore, when changing the position of the subject, it is necessary to refocus.

Tracking autofocus just designed for shooting dynamic scenes (for example, sports games, children or running animals). While the shutter button is pressed halfway, the camera continuously keeps its eye on the subject and tracks its distance as the distance changes. Automation determines the expected speed of movement of the object based on previous focusing data and focuses on the calculated distance. The focusing process does not stop until the photo is taken.

If the subject constantly changes speed, autofocus errors are possible, but they are minimal. Also, the quality of autofocus tracking depends on the illumination of the scene being photographed, the capabilities of your optics and the number of auto-tracking sensors that the camera uses. In the camera menu, AF tracking mode is displayed as

·AIServo - for Canon cameras;

·AF (C) - Continuous Servo – Nikon DSLRs.

You should keep in mind that constantly keeping a moving object in the camera's focus will significantly speed up battery consumption. Therefore, if you anticipate a long filming process, take an extra battery with you to the shooting location.

Automatic or intelligent autofocus. The camera electronics itself selects the focusing mode, determining whether the object in the frame is static or dynamic. This is convenient when you need to constantly keep many objects in view and it is difficult for you to predict which focusing mode you will need next. Also, intelligent autofocus often “saves” beginners. However, you have to admit that sometimes it is difficult for the camera system to guess your creative intent. Therefore, in the end you may end up with a picture that is far from what you would like. In the menu, Intelligent Autofocus mode is indicated as

· AI Focus AF - in Canon cameras;

· AF-A - from Nikon.

Focus points

Having decided on the autofocus operating mode, set the required focus point in the camera menu. This will let your camera know exactly where in the frame it needs to focus.

The focus point is a certain point in space that corresponds to the subject or part of it. As a result of autofocus, it turns out to be the sharpest in the frame. Focus points are also special marks in the camera viewfinder, with which the photographer associates the subject of shooting for subsequent focusing on it.

A DSLR camera allows you to focus on all possible or one at a time. given point. The accuracy and stability of autofocus largely depends on the number and location of focus points. And the number of dots itself depends on the model of a particular camera. In some modern modifications of professional cameras there can be up to fifty of them. However for successful work The nine or eleven focusing points found in most modern cameras will be sufficient for you.

The location of the focus points in the viewfinder roughly reflects the location of the camera's autofocus sensors. Autofocus sensors can work individually or complement each other for more precise focusing. The center sensor is often the most accurate.

Focusing on all points(or automatic focus point selection). Works in both tracking and single-shot autofocus modes. In the camera menu, automatic focus point selection is graphically represented as a white rectangle.

By default, the camera uses all autofocus points. When you don't have the opportunity to carefully configure, this can be convenient. The main thing to remember is that the camera, having received information from the sensors, focuses on the object that is located closest to it than the others or on the one that has the most contrast. Whether this is enough for your work or not - judge for yourself.

When you're using One-Shot AF mode, the viewfinder will highlight the points the camera has focused on. If you are not satisfied with the result of focusing, you will need to do it again. And in autofocus tracking mode, highlighting will not occur.

Automatic selection of focus points is appropriate if:

· the subject being photographed is dynamic (for example, shooting from a bus window) or the movement of the object is difficult to predict (for example, shooting a football match). In this case, it is simply not possible to select the focus point every time after the next movement. Focusing on all points simultaneously with the autofocus tracking mode works very well;

· the scene being filmed is located at a distance from the lens, and you want to get all the elements of the frame sharp (for example, a view of the city from a hill);

· if the subject is on a plain background, then the camera will not make a mistake in focusing (for example, a white object on a white background).

In other cases, to ensure that your photo is exactly what you intended to be sharp, choose the focus point yourself.

Center point focusing. Many photographers use single-point focusing to permanent job in single-shot autofocus mode: this is convenient in most situations.

Determine the central focus point in the viewfinder;

· point it at the main object of the future frame;

·Press the shutter button halfway until the lens focuses and locks the focus;

·recompose the frame according to your plan, moving the camera in one plane;

·take a photo.

This method is suitable for static scenes (for example, portraits, landscapes of product photography) and, of course, for frames where the subject is located in the center.

The central sensor of the camera is the most sensitive and accurate, so focusing on it can be used in low light conditions or vice versa, when you are working in backlit conditions and focusing is difficult.

Focusing on a specified point(or dynamic autofocus). The mode allows you to manually set any off-center point, which should be the sharpest in the frame. Switching points occurs using a wheel or joystick button.

For example, if you need to focus the viewer's attention on the background of the photo, then it is best to focus on the top points, then the foreground objects will be a little blurry. And when working on a portrait, try to match the focal point with the eyes of the model.

3 Dtracking.Used simultaneously with autofocus tracking mode. The photographer selects a point, the camera sensor focuses on it and continues to maintain focus as the subject moves or the position of the camera itself changes. Thus, the focus point moves automatically. In this case, the sensors take into account not only the distance to the object, but also its color, which makes focusing more reliable.

Lock autofocus to recompose the shot

You already understand why you need to activate autofocus, but blocking it requires special attention.

Autofocus lock (i.e. keeping the camera's attention on the subject the photographer wants) is most often used to recompose the frame. That is, you sharpened the focus, and then moved the camera so that the composition of the photo turned out to be the most successful. How to “convince” the camera to keep focus? There are two ways to do this.

After focusing in single-frame focusing mode, the camera locks focus and maintains it until you press the shutter button (until the photo is taken).

In order to ensure that the focus does not “go away” during the recomposition of the frame, you should understand that the automation actually focuses not on a specific cat, for example, which you are filming, but at a certain distance to this very cat. Therefore, if you change the distance during recomposition (move closer to the subject or move further away from it), the focus will be lost and your cat will appear blurry in the photo.

But all objects that are in the same plane as the cat (i.e. at the same distance from the camera) will be sharp. That is why, when recomposing a frame, the camera can only be moved within one plane (i.e. left and right, up and down).

Even moving the camera in the plane of focus may not be successful, depending on how much you move the camera, what your depth of field is, and what lens you have. Sometimes a better way to achieve sharpness in the desired part of the frame is to use a side focus point without recomposing.

Accordingly, if you shoot dynamic objects in autofocus tracking mode, then the first locking method is not suitable for you: when you move the camera, the focus will also shift following the focus point. In this case, you can use "autofocus trap"- focusing with the back button. The AF-ON (or AF-stop) button on professional cameras is the means that allows you to “catch” the desired object in the focus area.

On amateur-level SLR cameras, the AF-ON button is most often missing. However, you can use the menu to assign the AF-ON function to a programmable button (if there is one).

Be careful that when you switch the camera to AF-ON mode, it will not automatically focus when you press the shutter. In order for the camera to focus, you will need to press AF-ON, and when you release the button, the focus will lock. Refocusing will not occur until you press the AF-ON button again.

In what situations is manual focusing preferable?

Many novice photographers needlessly neglect working with manual focusing, preferring automatic focusing. In practice, situations arise when manual focusing helps to quickly achieve the desired creative result.

To start working in manual focus mode, set the switch on your lens to the “MF” position, and then rotate the focusing ring until the desired sharpness is achieved.

Let's look at situations in which it is more convenient to use manual focusing:

Shooting out of focus

Once you've learned and practiced all the techniques for proper focusing, you can try breaking them to get artistic out-of-focus shots. Of course, so that such works do not seem like just “damaged frames,” you need to think carefully about their concept and develop the idea that you want to convey to your viewer. To do this, you need to pay attention to objects that are interesting in their outlines and can give the pictures a certain mystical or surreal meaning.

Don’t forget that you may not get the desired shot the first time, but over time, when you become more familiar with your camera, the technology will become your reliable assistant in realizing your creative ideas.

Photos to illustrate the article were taken from the manufacturer’s official websiteTamron