Photos out of focus. Creating focus on a photo
One of common problems with macro photography is that the depth of field of our photographs can be so shallow that we cannot capture the entire subject in focus. Even with the smallest aperture possible, macro photography can severely limit depth. Only a certain part of the object comes into focus, and the rest of the scene remains blurry. Today we'll talk about combining photography and Photoshop to increase the apparent depth of field beyond what can be achieved with a single image.
Preparation
The method we will be describing is usually called focus stacking (English focus stacking). It consists in shooting several frames with different focal lengths and then combining them. This means that we will have several photos, each with a different part of the scene in focus, and then we will combine them into one image. The result is a photograph in which the entire subject is in focus, which we could not achieve with a single photograph.
For the article, I chose an Olympus OM-D Micro 4/3 camera and a Nikon 55mm Micro-NIKKOR macro lens attached with an adapter. The effective focal length of the lens was 110mm, thanks to the 2x crop factor, but to capture the entire watch in focus, we needed to use the stacked focus technique, which we'll talk about today.
This technique is most useful when using a macro lens. I chose an old lens model Nikon 55mm Micro-NIKKOR f/3.5 on camera Olympus OM-D. This combination makes for incredibly sharp macro photos. I used an adapter to attach F-mount lens k OM-D. It should be noted that OM-D– camera with standard sensor Micro 4/3 and crop factor 2x, i.e. in fact, the focal length of the lens becomes 110mm. Such a long focal length also reduces the depth of field of our photographs, so the focus stacking method is especially useful in this situation.
I chose a wristwatch as my subject, which is well suited to demonstrate the power of increasing depth of field through focus stacking. Since the watch is lying down, the depth of field is too shallow: we cannot focus the entire watch from the near to the far edge of the strap in one photo. It's time to use focus stacking.
I decided to set up the lighting to illuminate the clock from the side, so I used some inexpensive, removable constant lights (instead of flashes) and placed them carefully around the scene. I used a dark blue fabric as a backing to achieve maximum contrast between the subject and the background, and folded a small piece of fabric and put it on the top of the strap to position the watch in the most advantageous way. The watch itself is inexpensive, but quite suitable for our purposes.
Using multiple constant lights and a piece of fabric as a backdrop allowed us to create a simple scene even on the kitchen table.
Finally, if possible, I highly recommend that you have your camera connected to your computer when shooting. Our camera, unfortunately, did not support such a mode, but shooting in PC mode allows you to view the image from the camera while shooting on the computer screen, on a larger scale. This ensures that you get exactly the part of the image you want in focus.
Shooting
To demonstrate all the benefits of stacked focus, I chose a watch as the subject. When I laid them out the way you most often see them in catalogs, the image had too little depth of field from near to back of the strap. As I mentioned earlier, a long lens focal length and macro mode will reduce the depth of field, so we will have to use the focus stacking method.
In this photo, you can see that the depth of field is too shallow. At the end of the tutorial, you'll see how stacking focus fixes this.
After some thought and testing, I decided that it would take six images to achieve the required depth of field. My goal was to take different shots, with different parts of the clock in focus, and then combine them in post-production.
In the end, I made sure I got six good shots with different parts of the subject in focus. As a result of combining these focuses in Photoshop, I would get one combined frame in which the clock would be completely in focus.
When I started taking pictures for alignment, I started by focusing on the front of the subject, and then gradually moved the focus away from the foreground to the background. I got two shots of the front of the strap, two shots of the dial itself, and two shots of the back of the strap.
The very first frame received shows that there is no watch in focus in any photo; here we see only the near part of the strap as sharp, and the rest of the image is blurry.
Again, the idea here is that each single frame cannot bring enough of the subject into focus, but six combined images will give us a simulated unlimited depth of field. A large number of frames obtained during the shooting is necessary to make sure that the post-processing will be successful. Photos were taken at f/5.6 to add clarity and some depth of field, but even closing the aperture in macro photography is often not enough to increase the depth of field to the required level.
Be sure to use , and try to make the camera move as little as possible when shooting. Photoshop has a fairly powerful image alignment mechanism, but it's always better to get a good result at the shooting stage.
post-processing
While there are many different processing options that come into play, Photoshop has some great features that you can use to blend your focus. With their help, we can get the final flattened image in just a few minutes.First of all, I want to make sure that we have all the necessary images on the computer in a separate folder. I like to put all the combined photos in their own folder.
Now let's fire up Photoshop and start the focus blending process itself. Open the menu " File” (File), and navigate to “ Automates” (Automation) > “ Photomerge". This will open all of our images into one Photoshop document.
In the window Photomerge leave the option layout(Layout) set to “Auto”, and make sure none of the boxes at the bottom of the box are checked.
When the window opens Photomerge, select the folder in which all the necessary images are located. Leave the option on the left side of the window set to “Auto”, and then uncheck " Blend Images Together" (Image overlay). After you press OK, Photoshop will begin aligning the images and placing them in new document.
The process can take a few minutes, and when it's done, you should have a new document with all of our photos on separate layers. Now there is only one step left to combine the focus of these images.
Select all layers on the palette. To do this, you can click on the layer, then click Ctrl+A, or select layers one by one by clicking on them while holding down the key ctrl. Once all layers are selected, go to the menu “ Edit” (Edit) and select “ Auto Blend Layers” (Auto overlay layers).
Once all layers are selected, go to Edit(Edit) > Auto Blend Layers(Auto Overlay Layers) to open the focus alignment window. We leave the option set to “ stack images” (Stack Images) and the focus stacking process starts automatically.
On the menu " Auto Blend Layers" (Auto Overlay Layers) select “ stack images” (Stack images). Click OK again and Photoshop will begin the focus alignment process. After Photoshop is done, you can see the results both in the final image and in the Layers palette on the right side of the Photoshop window. You'll see that masks have been automatically added and aligned for all layers, and Photoshop has chosen which areas to hide and which to leave in the final image.
The final image shows a good focus stacking result. In comparison with earlier photographs, the differences are immediately visible: not a small part of the clock is in focus, but the entire scene. Focus stacking is an excellent method of sharpening through modeling.
Photoshop hides the blurry areas of each image using masks. The automated process prepared my mask layers perfectly. Photoshop intelligently chooses which part of each frame is in focus and then combines them.
Photoshop does almost all the blending work. The only negative is that if you are not happy with the result, it will be very difficult to somehow change the automatic calculations that the program has made. However, I still believe that the built-in mechanisms are quite powerful, and this may be The best way achieve a simulated depth of field.
Conclusion
Focus stacking is a unique technique that allows us to achieve an almost impossible depth of field. To easily get extra sharpness in a few clicks, we only need a series of shots and a bit of post-processing. Photoshop is a great tool that can intelligently align our images and automatically apply masks to them to achieve the desired result.Focusing can't be easy. Using any of the main shooting modes - auto, portrait or landscape - your camera does all the work for you. But it's too easy, and not professional. Everything seemed simple, you should press the shutter button halfway, focus and take a picture. Then why do many pictures come out blurry and blurry? The answer is that the autofocus system does work, but not always the way we want it to.
Usually, in reflex camera, entry-level or mid-range, there are nine focus points that are scattered at a certain distance from each other.
There is always one AF point in the center, then two points above and below, and three points each on the right and left sides, two of which are at the same level, and one is pressed to the edge of the frame. More advanced cameras have an additional six points, although these, unlike the first nine, cannot be manually selected.
How autofocus works
To achieve autofocus when shooting in various camera modes, information from all nine AF points is used. The camera determines the distance from each part of the scene from the camera, selects the closest subject that matches the AF point, and locks autofocus at that position.
This is normal and very useful if you want to focus on the nearest objects in the frame, but that's not always the case, is it? Let's say you're shooting a beautiful landscape, but you want to focus on a flower in the foreground. What to do in this case? - In such cases, it is better to select the manual focus mode.
Various focus options
Automatic point selection
By default, your DSLR will use all AF points in every shooting mode, but you can often select the focus points manually. Press the AF point select button, namely the button on the top right corner of the back of the camera (the location may vary depending on the camera brand) and a confirmation will appear on the screen that Auto Select is now using multi-point AF.
Single point focus mode
To switch between auto focus and manual focus, press the focus point selector button as in the previous step, but then press Set. The camera will now enter single focus mode. To return to multipoint mode, do the same.
Changing focus points
You are not limited to using only the center focus point in manual control mode. After switching to auto mode one point at a time, you can use the arrow keys to select any other available focus point. To return to the center point, press the "Set" button again.
Focus modes
The focus point selection guide works in any focus mode, so you can use either one point or multiple points depending on whether you are shooting a still or moving subject. Choose the most suitable focus mode.
When to Use Which Focus Point
Automatic selection
If you want to focus on the nearest subject and need to quickly react to what is happening around you, Auto Select mode is a great option for you. This saves time, since in this case you will not be busy choosing one or another point, in addition, it is good to shoot moving objects in this mode.
Center focus point
The center focus point is the most light sensitive and most accurate of the bunch, so it's great for use in very low light levels, or vice versa in very bright light. While using other points may lead to worse results. The center point is also ideal when the main subject is in the center of the frame.
Upper focus point
When you are photographing a landscape and it is important for you to focus on the more distant objects and areas of the scene rather than the foreground, it is best to use the top focus point. In this case, the foreground objects will be more blurred, and the objects that are far away will be clear and sharp.
Focus point diagonal
Portraits are especially good when the subject is not in the center of the frame, but slightly to the side. When shooting a portrait, either in landscape or portrait orientation, select the appropriate focus points diagonally and focus on one of the subject's eyes. If the face is screwed in three quarters, then focus on the eye that is closest to the camera.
Boundary focus points
Focus points located at the far left and right of the frame are very handy when you want to blur the foreground image and sharpen certain objects further away at the edges of the shot.
How to choose the best AF point
While nine possible focus points will be more than enough for most of us, high-end cameras like the Canon EOS-1D X come with an incredible 61 focus points. You can even select multiple focus points in small groups.
With so many focus points, choosing the best point can be tricky. It often seems that the easiest way is to use the center focus point, focus, then lightly press the shutter button to achieve focus.
You can lock focus settings by holding down the shutter button, compose your shot, and then fully press the shutter button to take a picture. This often works, but it may not always be the best option.
The main problem with using only the center focus point is that the lighting information and exposure value are set at the same time. That is, for example, you focus first on an object that is in the shade, and then quickly switch to an object that is in the sun, then the image will be overexposed.
Fix point
You can press AE Lock, then compose your shot so the camera can take into account constantly changing lighting conditions. While doing this, you should keep holding down the shutter button to keep the focus locked.
But it's usually easier to choose an AF point that's closer to the area you want to focus on, so any subsequent camera movement will be minimal.
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 are available for DSLR / SLR cameras from many major manufacturers in the range from -5 to +4. 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. The newest 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, and then let 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 lenses is more high level in 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 subjects with low contrast (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 a focus point directly on the subject and do not recompose the frame, 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 is natural. 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 focus in most cases (given that 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 likely, use a quick Google search.
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, while I gradually began to use cameras more and more High Quality, I've seen less and less need for sharpening, and now I'm only using 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'm shaking like California on its worst days, so I usually shoot for more short exposures. 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 more long exposure 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 like the Canon 50D and 1D/Ds Mark III have excellent front- and back-focus fit 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 to be saved in the image. This can make a 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 opinion in the comments - have you ever had problems with focus and sharpness?
It is no secret that now, in order to take a photo on an ordinary, so to speak, “soap box”, you need to press the button a little, after that the lens will focus on the object and then, when we already see a clear image in the viewfinder (or on the screen), press the button until end and take a photo. In principle, everything is simple and clear.
But Lytro decided to change that process. They claim they will revolutionize the world of photography. With their cameras, you can take a photo without focusing the camera on the subject. And you can adjust the sharpness already in post-processing. Honestly, when I first saw this, I felt like I was dreaming.
This technology has been developed at Stanford University under the direction of Dr. Ren Ng for a long time - about $ 50 million was invested in it. The company showed a few photos so that we can quickly understand what they invented. So, in the gallery, the link to which is below, you need to click on desired area photo and it is there that the photo will focus, and everything around will become blurry.
Example:
Focus on the girl 
Or on flowers 
Unfortunately, on Habré you can’t embed Flash into a post, so you have to go to the site and play around there. Go to the gallery and on the photos click on the places you want to focus on.
Publication date: 10.10.2015
What should you do if you get fuzzy footage on a regular basis? Is the technique to blame or is it your actions? This article will help you figure it out. In it, you will learn how to check the focusing system of the device for accuracy and adjust it to get sharp shots.
Nikon D810 / Nikon 85mm f/1.4D AF Nikkor
I would like to say right away that in most cases it is not the camera that makes the mistake, but the person working with it. So, for starters, it’s worth looking for the cause of errors with focusing in your own actions with the device. In recent tutorials, we talked about how to work with different autofocus modes and focus points. This knowledge will help you in practice. It will also be useful to read an article on how a novice photographer can evaluate and improve the quality of their own work.
Autofocus can fail when working in low light, and when shooting complex, diverse shots (the camera will not know what to focus on). Such focusing shortcomings can be avoided by simply setting the device according to the shooting conditions. For example, choosing the AF-C constant focus mode and 3D subject tracking when shooting sports will allow you to get much more sharp shots than working with single focus. But there are focus errors that occur systematically, regardless of the shooting conditions.
Back and front focus
In SLR cameras, the phase type of autofocus is the main one. It is with him that you are dealing, working through the viewfinder of the camera. Phase focusing occurs using a separate sensor installed in the camera. As you can see, this is a complex system, and sometimes it can work inconsistently.
The consequence of this will be systematic autofocus errors, called back- and front-focus. In the case of back focus, the camera constantly focuses not on the subject being shot, but behind it. In the case of front focus, on the contrary, the camera constantly focuses in front of the subject. Please note that the presence of back- and front-focus can only be said when the camera makes a mistake with focusing every time in the same direction. If one frame is sharp and the other is not, then the problem should be looked for elsewhere.
The problem of back- and front-focus is especially terrible when working with high-aperture portrait optics. There, the depth of field will be very small, therefore, any, even minor focusing errors will be very noticeable in the photo. For example, the sharpness in the frame will not be in front of the model, but on the ears.
On the other hand, if you are a happy owner of a whale lens or universal zooms that do not shine with high aperture, you can sleep peacefully. After all, even if your camera has back or front focus, you most likely will not notice it, because focusing errors will be compensated by a large depth of field.
Contrast autofocus
AT reflex camera In addition to phase focusing, there is another type of autofocus - contrast. You activate it, including live mode View and sighting the picture through the screen of the device. With contrast autofocus, there can be no back and front focus, since it does not require separate sensors for its operation, focusing passes directly on the matrix. Thus, if phase focusing regularly "smears", try switching to Live View mode and working with contrast autofocus. It works a little slower, but gives more accurate results.
Checking Focus Accuracy
How to check the camera for back and front focus? An accurate conclusion about the presence or absence of these shortcomings can only be given by an authorized service center manufacturer of photographic equipment. However, the photographer can make a preliminary assessment of the focus accuracy for himself.
We propose a simple algorithm for such verification.
First, let's prepare the camera.
1. Insert the battery and memory card into the camera. Turn on the camera.
2. Check if autofocus is enabled.
3. Press the Menu button, in the "Image quality" item, select "JPEG high quality". If you know how to work with RAW, you can use this format.
4. Turn on A (Aperture Priority) mode. If you know how to work with manual mode M, you can use it. Open the camera aperture to the maximum value. Everything is simple here: the smaller the number indicating the aperture, the more it is open. In the case of a kit lens, you will most likely have to deal with apertures around F5.6.
5. Set the minimum ISO value. This is usually ISO 100 or 200. This will ensure that test shots are clean and free of digital noise.
6. Now - the most important thing! Let's select the focus mode on one point. It may be called "Single-point AF" in the camera menu.
7. The point is small - download and print a special target on any printer to check the accuracy of focusing.
There are targets different kind, but the proposed option is perhaps the most popular. In principle, you can check the focus, say, using a regular ruler (how it will become clear later), but it is much more convenient to do this on a target.
Checking autofocus
So, the camera is set up, the test target is printed. Time to act!
The camera is best mounted on a tripod.. Without a tripod, such a check will be extremely inaccurate and indicative.
Provide adequate lighting for shooting. It is best to shoot by the window during the day. You can use a flash (both built-in and external).
Place the target on a flat surface, and position the camera at an angle of 45 degrees to it at such a distance that the target occupies a significant area of the frame.
Choose the center AF point. Focus exactly on the target - on the inscription Focus Here (Focus here). A thick black line with this inscription should be located in your frame strictly perpendicular to the optical axis of the lens.
Take a few shots. Do not use continuous shooting, focus again after each frame. Remember that after focusing, in no case should you move the camera, change the shooting distance. If you are using a zoom lens, test it at different focal lengths. I note that it is most convenient to test with focal length in the region of 50 mm, you can start with it.
View received footage. To see them better, do it not on the camera screen, but on the computer monitor. If you see a systematic focus error on all frames, then most likely you have detected back or front focus. It's not worth worrying about this. This is easily fixed in the service center. And owners of advanced cameras (starting with the Nikon D7200) can adjust the focus directly from the camera menu
Fine tuning autofocus
Advanced cameras (starting with the Nikon D7200) have an autofocus fine-tuning feature that will help you get rid of problems with back and front focus, fine-tune the focus system. The convenience of the function is also in the fact that the device remembers the settings separately for each specific lens. Let's say a bug shows up with one of your lenses. You can make adjustments specifically for him, and they will not affect the work with other lenses. When you attach a lens to the camera, it will automatically apply the appropriate corrections for it. Please note that autofocus fine-tuning will only work when focusing through the camera's viewfinder (with phase focusing). When working through the Live View screen, it is not activated, and there will be no need for it, because in this case a contrast type of autofocus is used, which eliminates problems with back and front focus.
Let's see how the autofocus fine-tuning feature works.
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