How to get in-focus and sharp pictures?
This week, I keep going with a new advice article! After offering you a lot of tips and techniques in different fields, we’ll now talk about an interesting subject: getting sharp and in-focused pictures! One of the first things we often wish to obtain when switching to an advanced camera like a DSLR or a mirrorless, since they have larger sensors than smartphones, compacts and traditional bridges, is to see more details on our pictures. Nevertheless, if these cameras are advanced, it is also because they require a good knowledge. So don’t think that buying a camera of this type is enough to suddenly get perfect images! The range of your camera will not be as important as the knowledge you have of it.
First, you have to distinguish between two points: in-focused and sharp. On these large sensor cameras, you can get those famous foreground and background blurs, also called “bokeh”, which is one of the reasons why we find them so interesting. The area where the image will be sharp, therefore between these blurs, is the focus area. The extent of this focus area is called depth of field. So, there is not a direct link with the level of detail, although the distinction focus / blur can accentuate this feeling. Indeed, a sharp area will look even sharper if it is in the middle of blurred areas! The sharpness, on the other hand, is indeed the level of detail of the elements located in this focused area.
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So the first thing to worry about is the area of focus, obtained by focusing. With short focal length lenses, especially with small apertures, this area will be very large. However, with slightly long or even very long focal lengths and large apertures, the focus area will often be very short. Thus, the slightest shift will make the picture look blurred when it is actually just that the focus area will not be where you were looking for it. Then, another parameter that may affect the sharpness of your image, whether it is the whole image or only the subject, will be the exposure time. Indeed, you have certainly heard of motion blur and subject blur, which are simply due to, in the first case, the movements of the photographer (therefore yours), and in the second case, the movements of the subject (therefore non-existent if it is stationary).
Regarding the sharpness, other elements come into play, but mainly the sensor and the lens. For example, the aperture, apart from reducing or enlarging the focus area, will not always deliver the same level of detail at all values and on the whole image. The range and type of lens are also important. The ISO sensitivity has an influence too, because the higher it is, the more digital noise will appear. Finally, in a more anecdotal way, the cleanliness or rather the lack of cleanliness of the lens and the sensor can also influence the image sharpness. I can tell you for example the story of this lens that was supposed to be able to deliver a very high level of detail. I bought it second hand and it arrived with a filter so tight that I couldn’t remove it right away. In my first tests, details were particularly blurry, and I was beginning to think that the reputation of this lens was exaggerated. That was until I managed to (finally) remove the filter, which was not a cheap one, and the results were (literally) clearly different.
So here are my tips to help you get maximum focus and sharpness whatever your sensor and your lens. Please note that I am talking about getting the most out of your camera in particular, don’t be surprised then if you compare an image shot with a micro 4/3 and a low-end lens and you don’t have the same maximum level as with a full-frame and a high-end lens.
Depth of field
Sensor and focal length
You will often hear that the size of the sensor does change the depth of field and that the larger the sensor, the shorter the depth of field. In reality, this is a mistake, the sensor does not change the depth of field. To get an identical framing, in the same conditions as on a smaller sensor and without having to move, we can choose a shorter focal length. For example, if you want a composition identical to that of a 35mm on a full frame, you will use a 23mm on an APS-C or a 17mm on a mFT. By the way, an article about focal length is available on our blog. Now, a shorter focal length like a 12 or a 16mm with the same aperture shows a greater depth of field (so, less blur). The advantage in our search for a high level of detail is that the risks of shifts when focusing will be rarer.
Conversely, on longer focal lengths such as 85 or 200mm, this depth of field will be shorter, and the risk of shifting will be greater. In other words, the more you use long focal lengths and compose tightly, the shorter the depth of field will be and the greater the danger of not having your subject in focus. This is true regardless of your sensor size, although it will happen less easily with smaller ones. But we’re talking here about mirrorless and DSLRs that will have at least micro 4/3 sensors, which are already large enough to easily get fairly short depths of field.
Focal length and distance
As mentioned above, the framing will require a certain distance from the subject depending on the focal length you use. Here again, the tighter you frame, the shallower the depth of field will be, either by moving closer to the subject or by increasing the focal length. Even with short focal lengths or small apertures, you can get very shallow depths of field because of your distance from the subject.
For example, wildlife photographers often use lenses such as the 150-600mm f/5-6.3, which do not have very large maximum apertures, and yet can produce sharp images of wildlife with very blurry backgrounds. Indeed, a long focal length combined with the fact that they get as close as possible to the animals to frame them at the most tight help out to strongly reduce the depth of field (and then produce those nice, blurred backgrounds). Just as you can also do with a very short focal length by getting very close to the subject, think of the field of view as a cone in front of you and imagine a colored area representing the depth of field surrounding the subject. Then, imagine how it would change if you got closer.
About the aperture of the diaphragm, this one will also affect the focus area. Indeed, the larger it will be, like f/2.8 or f/1.4, the more the depth of field will be reduced at identical distance and focal length. Consequently, the smaller the aperture (such as f/5.6 or f/11), the greater the depth of field. And you will often hear portraitists warn you about this. Indeed, with large sensors and large apertures, you will sometimes have a depth of field so short that it will not include the whole person, reducing the area of sharpness to only the face and drowning in the blur the back of the head, which means the hair (if there is any, let’s think of bald people!), or even the tip of the nose. If the person is from the side, you will even see the difference between the eye in focus and the other one.
As we saw above in the point about focal length and distance, the shorter the focal length and the farther the distance, the greater the depth of field. This means that with short focal lengths and a distant subject, the area of focus will often be very large, even with a large aperture. On the other hand, with long focal lengths and a close subject, it will be much smaller, even with a small aperture. It will therefore be necessary to be more careful in the second case than in the first one, which may seem paradoxical since most of the time, we advise to close the diaphragm in landscape while we often use very short focal lengths, and we advise to open it to the maximum in wildlife photography because we usually lack more light than in landscape, and we have more difficulties to compensate for this lack (for example, using a tripod in wildlife photography allows our arms to relax, but it does not stabilize the animal). Do you still follow me?
All these notions are important since they will be meaningful when you will focus on the subject. Depending on the result you wish to obtain, and especially if you wish to accentuate the blurred foreground and background, you will have to start by choosing the framing according to your focal length and to the distance from the subject. This will largely determine the extent of your focus area. Then, you will have to select your aperture and, finally, ask the camera (if you are using autofocus), or if you want to focus manually, locate the subject in the image.
Precision will then be crucial, because the shorter this focus area is, the more the movements will affect the image. As a small aside, we do not encounter this problem on mirrorless, but if you use a DSLR, you should know that the phase detection autofocus used in optical viewfinder is very fast but also imprecise, and it is not uncommon for this to cause shifts. As a matter of fact, manufacturers have even included on most of their cameras an option to correct (more or less) these shifts. Sigma and Tamron have even gone so far that they propose USB consoles allowing to correct them in a more precise way. You can find many tutorials on the internet showing you the procedure to follow to check your camera. This is something that every DSLR user should do every time they buy a new lens. Because it is illusory to think that manufacturers can make, with this autofocus, perfectly calibrated lenses all the time.
Regarding the autofocus, it will therefore be essential to select its mode: simple or continuous, with tracking on a single AF point, a group of AF points or all the AF points of your camera. Remember that the more you have, the more precise but the slower it will be. You are just as likely to miss your focus with a lot of accurate AF points but not fast enough to follow the subject, as you’ll be with a few faster AF points but not accurate enough. Obviously, the more high-end the camera, the more likely it is to be fast AND accurate. However, don’t be convinced that you absolutely have to buy a 5000€ camera. Most cameras, and even entry-level ones, have autofocus systems that are good enough for most situations, as long as you select the right mode.
I would personally advise you to use continuous mode, especially with a very shallow depth of field. Indeed, the slightest of your movements may make you miss your focus, even if the subject is still. It is not uncommon to lean slightly forward or backward between the time you focus and the time you shoot. On stationary subjects with large depths of field, the single mode will often be enough and will speed up the focus a bit. Of course, if you are in manual mode, you will have several techniques. For example, hyperfocal allows you to maximize the focus from the closest distance to you to infinity. Focus peaking highlights the area of sharpness on your screen. But in the end, you won’t be in a position to blame your camera that much if you miss the focus, darn it!
Sharpness of the image
The lens and its diaphragm
Now that you have chosen the appropriate settings for your camera so that the focus area is where you want it and extends over the area you want, we can take a closer look at the level of detail in this area, namely the famous sharpness. The first part influencing is the lens, the one that transmits the light to your sensor through a set of lenses. Of course, the better these lenses bring light with precision, the better the details will be. As often happens, the higher the price, the better the quality, because the best lenses that have undergone the best treatments are more expensive to manufacture, and therefore more expensive to sell as well.
However, nothing is ever simple, the lenses of “manufacturer” brands such as Canon, Nikon or Sony are also more expensive because they carry the name of these brands. And it is not uncommon to find Sigma, Tamron, Tokina or other lenses showing as good, or even better results for much less money. Nikon’s 35mm f/1.4G, for example, is overall worse than the Sigma Art, and even worse than the recent Tamron while being the most expensive of the three. We even find in these brands lower-end lenses proving almost as good as the high-end versions, like the Nikon’s 35mm f/1.8G compared to the f/1.4G, or the Canon’s 35mm f/2 IS compared to the 35mm f/1.4L. Generation difference can also influence. For example, the 24mm f/1.4G from Nikon supposedly more high-end than the f/1.8G is finally not as good and released much earlier, as well as the 85mm f/1.2L from Canon compared to the recently released 85mm f/1.4L.
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And indeed, nothing is ever really simple, because apart from some exceptions, most of lenses have differences in sharpness according to their aperture, and even according to the focal length for zooms. Although on high-end lenses, manufacturers do their best to ensure a high level of optical quality from the largest aperture and thus limit the differences between apertures, they rarely succeed. It is even more obvious on lower end lenses, where they will have other priorities (like reducing costs, in fact, look no further! ahah). Prime or zooms, most of lenses have a lower sharpness level at larger apertures. And regarding zooms, most of them will be worse at extreme focal lengths (24 and 105mm on a 24-105, for example). But one last time, nothing is ever simple and there may be some zooms better at the ends than in the middle of the zoom, so you’ll have to rely on tests, or even test it yourself to know where you stand.
Finally, last little thorn in our side: the sharpness is not always the same on the whole image! Usually, the edges of the image lag behind compared to the center, but once again, a test is always useful as we sometimes have surprises, like edges as good as the center but the area between them which is less good, for example (do not ask me why, but it does happen, although it is quite rare). And moreover, even if it improves by closing the aperture, it does not necessarily do so uniformly, and it is not uncommon that the center improves faster than the edges, or conversely, when the center is already very sharp at full aperture, only the edges improve… You should therefore know that in a general rule, lenses provide their best sharpness at medium apertures, around f/4 for lenses opening at f/2 and more, around f/5.6 for lenses opening at f/2.8, and around f/8 for those opening less wide. Of course, this is not an absolute truth, and you will have to test your lenses to be sure.
Finally, don’t think that you can simply close your diaphragm to the maximum to overcome this problem, especially on lenses closing at f/22 or f/32. At these apertures, a phenomenon called diffraction appears and affects the details, more and more strongly as you close the diaphragm. And the smaller your sensor is, the faster this diffraction happens. So, on a full frame, when it occurs at f/16, then on APS-C it will start to affect the image at f/11 on APS-C and at f/8 on mFT. If you extend this principle on compacts with 1″ sensor or on smartphones, it will happen even earlier. So don’t be impressed by a bridge like the Panasonic FZ200 with a 25-600mm f/2.8 lens, because with its 1/2.3″ sensor, the diffraction is almost already at work at full aperture and will quickly get worse when closing the aperture!
Values indicated above are not to be taken literally, they are correct in the case where you will use a definition around 20MP. But as always in photography, the more the enlargement is important, the more we see the defects, and vice versa. So, if your sensor or the support on which you display your images only uses 8MP, the tolerance is greater, and the diffraction will be less quickly visible. On the contrary, if you have for example an FF 60MP sensor and you zoom in at 100%, you will already see the diffraction effect at f/8. Remember that the smaller your sensor is, the better it is to avoid closing the aperture too much!
Photography is a moment fixed on a sensitive support; it is therefore necessary to indicate to the camera the time needed to capture the light sent by the scene through the lens. So, if you have ever held a camera, you have probably seen numbers such as 1/1000, 1/250, 1/10,2’… Again, if you are not very familiar with this concept, you will find on our website an article on shutter speed, we definitely bend over backwards for you! But to take a simple example: move your hand quickly in front of you and you will realize that the faster you move it, the less you can distinguish the details. If you take a picture of your hand with a long exposure time (e.g., 1 second), it will have the time to travel a certain distance during this second and your camera will record it. This is called subject blur, your hand being the subject. In order to freeze it, you’ll need to find a short enough exposure time, and the faster your hand moves, the shorter that time must be, obviously. A lot of beginners get fooled by this subject blur, because they don’t know yet the difference between this blur and a lack of sharpness. Just be aware that if the moving subject is blurred and the elements around in the focus area are sharp but not moving, then you are probably dealing with subject blur.
Another blur related to shutter speed is motion blur, which is also caused by movement, but this time, it’s your own! Indeed, when you hold your camera handheld, even if you think you are very stable with nerves of steel, you always slightly move, and these movements can affect your final picture. The “rule” that you will often find indicated everywhere is the one of 1/focal length. Assuming that you are handheld and you don’t have any stabilization (neither on the sensor nor in the lens), if you are using a 50mm then you must use an exposure time of 1/50th of a second or shorter to avoid motion blur. This rule applies to all sensor formats, but it must be adapted because it firstly concerns the full format. With a smaller sensor, you must at least apply the famous “crop factor”, that’s to say that an APS-C has for example a diagonal 1.5x smaller than a full format. You must therefore multiply the focal length by 1.5. In our example of the 50mm, you will have to use at least a speed of 1/75th of a second. With an mFT, you must multiply it by 2. For other formats, I invite you to inquire about their diagonal and compare it to that of the full format. I would even advise you to take a safety margin with full format sensors more pixelated or with small sensors: multiply by 2 for APS-C, and 3 for mFT, as an example.
If you have a lens, a sensor, or both with stabilization, the rule still applies but the stabilization will allow you to extend the exposure time a little more, depending on its efficiency. For example, a 100mm stabilized or mounted in front of a sensor with stabilization will be able to support exposure times longer than 1/100th. If the stabilization offers a gain of 2 stops, you can divide by 4 the exposure time, or use a shutter speed up to 1/100×4 = 1/25th. For this reason, cameras with stabilized sensors, like most of the recent Panasonic and Olympus or the latest Sony and Nikon full frame mirrorless, have an advantage because the stabilization on the sensor allows you to benefit from it even if the lens does not have it. It is especially interesting on long focal lengths. If you have understood this rule, the longer the focal length, the shorter the exposure time, but it often requires an increase in ISO – anyway, we will come back to this point later. This is the reason why telephoto lenses are more often stabilized than wide-angle lenses, as well as in video since your movements are continuously visible.
You will frequently have to worry first about the subject’s movement if it is moving, because unless you use a long focal length, the exposure time needed to freeze a subject will generally be shorter than the one needed to avoid motion blur. On the other hand, for still subjects, it will be better to focus on your own movements. But in both cases, there are solutions to reduce or even totally avoid these blurs such as a monopod, a tripod, or a flash. The monopod will allow you for example to reduce the risk of motion blur, as would do a stabilization, even if it remains limited. Thanks to the tripod, you will be able to use the exposure time of your choice, but remember that it does not reduce the risk of movement of the subject, just like the monopod and stabilization. For the subject, as long as it is not too far from you, the flash will be very effective since it freezes the action at a different exposure time than the one set on the camera.
After the aperture and the shutter speed, only one parameter was missing to validate the exposure triangle in photography, and this is now a done deal with the sensitivity. Digital technology has allowed a great latitude on this parameter, because in the silver age, films were limited to a single sensitivity – even if you could “push” them a little, but not too much at the risk of strongly degrading the image. So, you had to change film in order to change sensitivity. Today, we can go from 100 to 128 000 ISO with only a few turns of the wheel, or even by letting the camera do it automatically in a thousandth of a second. Thanks to this parameter, we allow the sensor to be more sensitive to light, although it is actually only an electrical amplification of the signal, but I’ll skip the technical details.
However, this amplification is not without drawbacks (it would be way too easy!). The higher you go in ISO, the more you will have what is called “digital noise”, which is characterized by colored dots randomly distributed throughout the image. Thanks to processing algorithms, we can reduce this noise. The software will analyze it and try to make them disappear, but it will result in a smoothing of the details and what could be called “grain”. But this term should not apply in digital. Indeed, in the days of film, it was made up of silver grains, hence the term “silver”, but in digital, this grain is not even noise but a consequence of its reduction.
So, the higher you go in ISO, the more details of your images will be affected. Ideally, if you want to get as much detail as possible on your images, you should stay at the lowest ISO setting. But obviously, this will be difficult in many conditions, if not impossible. So you will have to use all the techniques seen before: a flash, a tripod, a wide aperture… The best is of course to shoot in the brightest conditions possible, but I know it is sometimes complicated to invoke the Sun God in the middle of the night (well, you can still try, but I’m not sure you’ll get an answer).
“But what vibrations?” you may ask… I am not talking about good vibrations of a song, obviously. And yes, despite all the precautions you will have taken by following the advice indicated in this article, there is still a way to improve the chances of getting even more detailed images. In a camera, there are often a lot of mechanical parts moving, like the shutter or the mirror, and when they move, they make the camera slightly vibrate and then add micro blur. There is also the micro-movement caused by those things you have in your hands: yes, I’m talking about your fingers which, just by pressing the shutter release, also add micro-shake, even if you use a tripod!
Don’t get paranoid either! If you follow all the tips, you will already have very detailed images, whatever your camera. But if you want to go even further in the search for the finest details, there are also other “little” tricks, like using the self-timer or the remote control so you don’t have to press on your camera with your big hands full of fingers, haha! On most DSLRs, you will find a Mup mode, meaning “mirror up”, which consists in raising the mirror for a defined period before the sensor starts recording light, so as not to suffer its vibrations when it rises and closes. On some cameras, you can also choose between mechanical and electronic shutter – the electronic shutter does not cause vibration but can cause other undesirable phenomena, especially on large sensors, although this is less and less the case.
Let’s recap and conclude
When you are beginning in photography, all these things are often obscure and you tend to blame your equipment, especially when it provides you with images that don’t seem to be better than those you can do with your smartphone or your old 2000’s camera. How many times have I heard some people complaining about the details of their 50mm f/1.8 on their APS-C DSLR, to realize that their pictures were made at 1/30th of a second? And to be honest, how many times did I complain about this myself when I started out?
So, you should know that nowadays, cameras and lenses sold are capable of providing very detailed and even excellent images, as long as you know how to use them properly. Before buying a new lens because the one you are using lacks detail, start by following all these tips and you will see that most of the time, it will suddenly be able to provide you with very sharp images. So, learn to master your camera and get the best out of it! You will realize that in most cases, it will do what you expect it to do with quality, and the results obtained will be further enhanced by image processing, especially sharpening. But this is part of another aspect of photography (processing and editing) that would deserve one, or even several other articles (be patient, they are on their way!).
In order of importance, so to speak, here are the steps to follow in order to get the best sharpness of an image:
- Set your focus,
- Choose your shutter speed (think about motion blur and subject blur and consider stabilization, if available),
- Set your aperture (avoid the maximum aperture as well as the ones causing diffraction),
- Set your ISO sensitivity (the lower the better, even if it means using a tripod or a flash),
- Reduce vibrations as much as possible (softness on the shutter release, self-timer, remote control…).
Don’t forget that a good picture is not necessarily a picture full of details on which you can count the blades of grass and the hairs on your head… It is above all a picture that gives off a certain emotion. Focus first, especially if you are using large sensors and long focal lengths with large apertures. Another important point. Many of you will want to look at your images 100% on software or on your camera, which may highlight the lack of detail (when there is). Remember one thing: those who’ll look at your pictures will rarely see such large enlargements. Also, as mentioned in the article on megapixels, the more you enlarge, the more likely you are to see the lack of detail, and the less you do, the less likely you are to see it. Do you often show A0 posters of your vacations to your friends?
Concerning the quality of the lenses, luckily, many test websites are available on the internet to give you precious information about their characteristics, and in particular about the sharpness. But beware of some websites, even if they look serious, which may not always use a strict methodology. For example, many forget the last sentence of the previous paragraph and what it implies when comparing 100% crops of lenses tested on cameras of different definitions. A serious site like DxO will have some interest because they carry out their tests in labs without influence of the conditions, and then standardize the results to compare fairly all the material. Lensrentals is also one of the rare sites to test several copies of the same model in order to take into account the variations between them. Be careful though as these websites can be described as quite technical and require you to know how to interpret their results for them to be really useful.
I hope this article will help you exploiting your equipment to its full potential and make you realize that great power implies great responsibility… Ah no, that’s Spiderman! Rather I meant that good photography involves a lot of skill and experience, long before having a big, high-performance camera and expensive lenses that look like bazookas. It’s also better to have a beautiful photo full of history and emotions than a banal, sharp, noiseless and blur-free photo, isn’t it?
See you soon,