Transcripts
1. Hi: Hi, my name is Hugh, and welcome to this class on Bokeh and background blur in photography and videography. Let's start by comparing three images. Here's 1, 2, and 3. Which one do you like the best? 1, 2, 3. They're all very similar. The framing is very similar and they were taken a few seconds apart, but which one speaks to you as being the best quality? I think most people would agree that this looks the best. It's the most professional looking. That's of course because it's got this separation between the subject, me, and the background. Whereas in this image here, there's a lot less separation between me and the background, which is all pretty much sharper in focus. If you're interested in learning about portraiture and depth of field and background blur. Welcome. This is the right class for you, and I'll see you in the next video.
2. Introduction: If you've engaged in the YouTube photography or videography communities over the last few years, you will know that chatter about bokeh and background blur is constant. That's not necessarily a good thing or a bad thing, but I think it can lead to misconceptions about background blur and photography. First of all, it's very important to note that background blur is not the secret to good photography or videography. However, it can significantly enhance the production quality of your photos or videos. Secondly, it's easy to get the impression that in order to get blurry backgrounds, you have to invest a lot of money in expensive lenses. However, that's also not really true. In fact, it's extremely achievable to get beautiful photos and videos with blurry backgrounds with the gear you have laying around right now. In this class, we're going to learn, first of all, when and why you'd want to use a blurry background, and when it's appropriate, not to use one, because there is a big difference. We're also going to learn how you can achieve that blurry background look, especially on a budget.
3. What do you need for this course?: What do you need for this course? Well, it will help to have a camera especially one with an interchangeable lens, but even if you don't have one of these, that's quite okay. At the end of the course, we're going to talk about how we can achieve this blurry background look even with your phone. If you have a camera lying around, it will work. It doesn't matter if it's not digital, it doesn't matter if it's not mirror less. It can be a DSLR, an old SLR, anything will work, it doesn't matter.
4. Class project: As I said at the start of this course, there is a misconception out there that only the lenses that have the widest possible aperture will be able to produce beautiful, blurry backgrounds. For the class project, especially if you're on a budget, show me that you can achieve those blurry background looks that you're after even without using F1 or F1.4. For this project, you can show me anything, videos or photos with varying degrees of blurry backgrounds. It doesn't have to have a blurry background. In fact, it could be the exact opposite, but just submit something that shows me that you understand better how depth of field works and how you can control it with various different settings.
5. Technical stuff before we start: Just to keep things simple, at the end of every lesson, I'll provide a quick and easy summary of the things that we've learned from that lesson. Unfortunately, to describe the things that I need to, I'm going to have to use some jargon and a technical language. At the start here, just let me define a few important things. The aperture of the lens is the diaphragm which allows light to pass through the lens and to hit the sensor of film. Wider apertures like this, let in a lot of lights and narrow apertures let in less lights. As a consequence of this, aperture affects the exposure. All things being the same, if you use a narrower aperture, less light will come in and your photo or video will be darker and the converse is true when you use a wider aperture. When you use a wider aperture and let more light into the camera, the plane of focus, that's the area of which things are in focus, gets smaller. When you use a narrow aperture, more of your scene will be in focus. Just to confuse you, a lens like this one, which has a maximum, that's a widest aperture of f1.4, is called a fast lens. This lens only opens to a maximum aperture of 2.8. It's slower than this one. Be careful when we talk about fast and slow lenses because this can also be used to talk about a lens's auto-focusing speed. If you have any prior experience in photography, you'll know that aperture is measured in f-stops or t-stops if you're using cinema lenses. Confusingly, f-stops go up as the apertures gets smaller. F22 is actually a very small aperture and F1 is actually very wide aperture. It'll be extra confusing, you could say that a small F-stop is a big aperture, and a big f-stop is a small aperture but that's incredibly confusing. In this course, I'm not going to use the words big and small. I'm just going to talk about low f-stop and high F-stop and wide aperture and narrow aperture. Remember, low f-stop means wide aperture, and high F-stop means narrow aperture. Finally, you might hear the term wide open if you're watching YouTube videos on portraiture. This just means that the lens is being used at the widest possible aperture that it will go. For this F1.4 lens, if I showed it wide open, I will be shooting at f 1.4, that's the widest aperture. There are probably a few definitions that I've forgotten about, but we'll deal with them when we get to them. A lot of the time, I'm not going into huge detail partially because I don't trust myself to get it right. What I'll do is I'll put this graphic up and that will mean that you can do a bit of searching if you want to do a deep dive. Now for the sake of simplicity in explaining all of this, I'm going to talk about photos, but just know all of these principles are the exact same for video. The first few lessons are going to be divided up by the ways in which you can create background blur. There are lots of different factors and aperture isn't the only one. If you want to learn more move on to lesson number 1 it's easy.
6. Factor I: Aperture: What are the factors that contribute to depth of field and blurry backgrounds? Well, number 1, as you probably know, is aperture. Let's get that out of the way first. As I mentioned at the very start, as we use wider apertures, that's lower f-stops, the depth of focus decreases and we get blurrier backgrounds. The opposite is true when we use higher f-stops. That's narrow apertures. Let's have a look at these photos just to see what I mean. We're going to have a look at these images in Lightroom now. Thanks to my wonderful mom for being a willing and gracious volunteer. The focal length, that's how lens magnification is measured, is kept the same and the aperture is the only thing that is changing. I've exposed the shot with shutter speed and ISO, both of which do not affect the depth of fields. I'll say the averages out loud, but you can obviously see them over here in the top right-hand corner. Now, the ISO and the shutter speed, I've changed to expose for the shot correctly and I haven't done anything in Lightroom apart from change exposure. It was a slightly cloudy day, so the exposure did change quite a bit. That's 2.8. Here is 3.5. Still pretty blurry, 4.0 seeing a little bit smaller. 4.55, F6.3, F8, F9, F11, here's F14, F16, F22. By this stage, as you can see, I've used a slightly higher ISO here to get the shot right. But as you can see, the background is pretty sharp. If we now compare that to our shot from before, back down to F2.8. As you can see here, if our F2.8 on the right and our F22 on the left, everything else being the same, our backgrounds are drastically different. The portraiture qualities that are associated with the image on the rights are quite apparent. On the left, we don't really get that portraiture look. In summary, as we already knew, aperture does affect the blurriness of the backgrounds. If you want to blur your backgrounds, use a low f-stop.
7. Factor II: Focal length: Onto factor at number 2 and that's focal length. In this set of images, we've kept everything the same except for our focal length which is up here. Now, aperture is the same because that affects the depth of field. The ISO and the shutter speed will change to expose the shot. But as I said before, that doesn't affect the depth of field. Here we're at 25 mills. Have a look at the backgrounds. Fairly sharp. Thirty-five, 50, 70, 102, 135, 200. There is a fairly dramatic difference between our shots at 200 mills versus our shot at 24 mills. Obviously, as we increase focal length, the magnification in our images changes. But if you pay close attention, so does the appearance of the backgrounds. As you'd expect from longer focal length, our perspectives change quite differently and the relationship in size between our subject and the background is different, but the actual degree of blurriness of the background is quite consistent over the two images. But as you can see in this comparison, our image 200 mills has a much more creamy portraiture look than our image at 24 mils. This process is often called compression and it makes your photo is quite attractive. It's also why portrait photographers typically use longer focal lengths. This is a slightly more scientific example where I've got my camera on a tripod. Obviously the vase and the painting in the background are not moving. We're going to start at 35 millimeters. F2.8. This is on a full frame sensor, so he is 35, he is 50, 51 technically. Here is 70 mills, 100 mills, 135, 200. Obviously, if we look at the difference between 135 over here on the right and 35 millimeters, the perspective is very different and the appearance of the background is quite dramatically different. But if we actually zoom in, you'll see that the difference in the quality of that background isn't very big. There is some advanced physics going on here that explains why there is a bit more blur in these out-of-focus areas on our longer focal length. But actually the primary reason that there is difference in the background quality is perspective. The difference is not because this is more blurry, the difference is because of the perspective. If we were to zoom in, you get a fairly similar image. Obviously, this is a more compressed version of this photo. Yes, there is a little bit more blur, but really the reason that this has more of a portraiture look is more because of the compression than the difference in the appearance of the backgrounds. I hope that makes some sense. These images were shot at F2.8, but this is true across different apertures as well. This shows us that the focal length of a lens does affect the blurriness of the backgrounds. It also means that it's quite difficult to get blurry backgrounds when we're dealing with wide lenses. In summary, if you want blurry backgrounds, use a longer lens.
8. Factor III: Distance to subject: Onto factor Number 3, distance to subject. Have look at this set of images where everything stayed the same. [inaudible] camera settings, the subject stayed still, the background stayed still, but I moved relative to the subject. In this set of images, I've moved closer to my subject with my settings, 50 millimeters f2.8, the same. I'll keep my reference image on the left so you can see, but watch the background and how it changes as I move towards my subject. As you can see, as I get very close, the background is quite dramatically different. I won't go into the physics about how this works mainly because I'm not smart enough, but if you want to do a deep dive, it is quite interesting stuff. As you can say, the appearance of the background is quite dramatically different as we get very, very close. In summary, if you want that portrait look, move close to your subject.
9. Factor IV: Distance to background: Back to number 4 is the distance between you, your subject, and the backgrounds. In this set of images, I and the subject moved relative to the backgrounds and everything else stayed the same. In this set of images, my subjects and I have both moved relative to the backgrounds. Again, on the left, I'll set my reference image. All the settings of the camera are the same, 67 millimeters or thereabouts, 2.8. Let's go. Watch the background as we move. As you can see, as we increase the relative distance between myself and my subject in the backgrounds, the appearance of that background becomes quite different and we get more of that background blur when we get farther away. Again, in summary, if you create a deeper depth of field, you'll see more background blur and get that portrait look.
10. Factor V: Sensor Size: Factor number 5 is sensor size. Now, on a technical level, this is actually the same aperture and focal length, but because sensor size makes a difference to aperture and focal length, I'll address it here. There are a lot of misconceptions about crop sensor cameras and whether you should use a full-frame sensor or you can use an APS-C or Micro Four Thirds sensor. In reality, you can get what you want with any sensor. Don't let anybody tell you that you need full-frame. In fact, I used to shoot full-frame on this Canon 5D Mark III for many years, but now I use an APS-C Fuji because I like it more and it's smaller. My images are just as beautiful and no one could ever really tell that I wasn't using a full-frame camera. To demonstrate this, I've set up a scene with a tripod and a vase, and a painting, everything will stay the same, and this will hopefully show how synthesized effects background blur. As you can see down the bottom right-hand corner, we're on an EF 70-200 F/2.8. I'm shooting at 100 mils and at F/2.8. Here is our full-frame sensor, and here is our APS-C sensor. Obviously, these images are quite drastically different in perspective, but we can actually make these images identical if we use the right settings. The sensor in this Canon Rebel is 1.61 times smaller than the sensor in my 5D Mark III. If we use a focal length of 161 millimeters, we get this image. The other difference that you might be able to appreciate if you look carefully, is that the blurriness of the background on our right-hand image is slightly more than the blurriness of the background on the left-hand image. That's because, in order to get the exact same images, we actually need to use that crop factor on our F-stop as well. Instead of using F/2.8 if we times 2.8 by 1.61, we get about 4.5, and here's our result which is almost identical. Actually, sensor size is just the same as I was talking about with regards to aperture and focal length. If you're trying to copy the settings of somebody else, just remember that different sensor sizes work differently in this regard. That doesn't mean that you can't get beautiful portraits on smaller sensors. But just know that if you're buying a 50-millimetre F2 lens for Micro Four Thirds, it's not going to have the same qualities as a 50 millimeter of F2 on full-frame. Your 50 millimeter F2 on Micro Four Thirds is going to be more like a 100 millimeter F4 on full-frame. As you may well know, some lenses are designed for crop sensor cameras and won't work on full-frame cameras. But this phenomenon is only to do with the sensor, and the different types of lenses you use, whether they're designed for crop sensor or designed for full-frame doesn't really matter. Just to make that point very clear here are two photos I took both with sensors of about the same size, they're both APS-C, even though the canon is slightly smaller. On the left, we have a full-frame lens, on the right we have an APS-C specific lens, but as you can see, the images are almost identical. In summary, smaller sensors will get less blurry backgrounds at the same settings when compared with larger sensors. But you can still get good results no matter what you use.
11. Getting a portraiture look on a budget: All of these factors that I've just spoken about, contribute towards the ''portraiture'' qualities that [inaudible] of your photos and videos. What can you do if you're on a budget? Well, obviously, as we spoke about, longer lenses and wider apertures make for prettier backgrounds. Here is the kit lens that came with my Fuji. Remember, this is an APS-C camera. Our settings are actually 55 millimeters at full, but it's a full film equivalent of about 75 millimeters F6. Yet I still got beautiful backgrounds. Why is that? Because we're using a longer focal length. We're keeping our aperture as wide as I can even though it's not very wide, and I'm using the fact that background is far away, and I'm getting close to my subject. I'm using all of those factors as best I can, to get blurry backgrounds. I think you'll agree it's a nice portrait. I no longer have the kit lens that came with my cheek, Rebel Kiss X4, but I do know that it was an 18-55 F3.5-F5.6. Remember, because it's a 1.61 times crop factor, it's more like a 30-90, F5.6-F9. I don't have that lens anymore, but I can use a different lens to try and get the same effect as we saw in the focal length section. It's really hard to get any background blur at 30 millimeters, even on full-frame, even with a very wide aperture. However, if we use the longer end of this kit lens, which is about 90 millimeters F9, we can still get nice blurry backgrounds. Again, this is just because it's a longer focal length, I'm using the widest possible aperture that I can, it's wide open as they say, and I've kept a small distance between me, and my subjects, and a bigger distance between my subject, and the background. This results in a really pretty portrait, even though it's using the cheapest equipment that I could find.
12. Important considerations with shallow DOF: When you're thinking about blurriness of backgrounds, it's important to talk about focus as well. Obviously, you're going to miss focus more often if you're using a very wide aperture, like F1.4 versus F4. If you're using F1.4 on a full-frame camera at a wedding and you're shooting more than one or two people, it's going to be really, really difficult to get everybody in focus, especially if you've got two rows of people. In this case, I strongly advise you to step your aperture down to the full-frame equivalent of at least F2.8, more like F4. If you're doing video and you're manually focusing, it makes a big difference. It's really hard to get focus if your depth of focus is very small because subjects move around. If you're talking about a video while I focus, your camera will probably struggle, if you use a very narrow depth of focus. You'll see more hunting and you'll see jerky steps, even with the best camera systems out there. If you're interested in learning more about this, there are some calculators online, where you can plug in all your details and work out how big a depth of focus you have and this can help you to plan your shots if you're doing filming, especially for interviews.
13. When should you stop down?: Just quickly, we should also talk about when it is and isn't appropriate to get that blurry background. You're always looking for that shallow depth of field. It's going to be really hard to get shots when people are moving around a lot, and so I recommend stepping down your aperture. Also, in scenes where there are multiple people, you probably do want to have multiple people in focus, and so I encourage you to step down there as well. If you're doing street photography, I would strongly encourage you to set your aperture at something like F8-F11. It's just going to make your life a lot easier, everything will be nice and sharp, and it will also make your lens a bit sharper. Lens sharpness is a bit of a myth and I encourage you to do a bit of a deep dive on Ken Rockwell size if you find out more. But it is certainly true that most lenses get sharper, or have a sharpness sweet spot somewhere in the middle of the aperture range. At the wider apertures, your lens probably won't be as sharp, especially in the corners, and will be more subject to chromatic aberration like this. At the very narrow end, diffraction causes image degradation, so there are some image quality reasons for using those middle apertures as well.
14. Getting bokeh in Photoshop: But what happens if for whatever reason, you don't have that blurry background you're after? Luckily, there are things that we can do in post to fix this. In this photo, obviously I've got a little less blur than I might like. Level, that'll do. Okay. Now let's go to Edit in Photoshop. Now my Photoshop experience and skills are extremely low so you can pick this up very quickly. I'm just going to show you the absolute most basic way that you can achieve this. I'll leave some links down in the resources section below so that if you want to learn how to do this properly, you can learn from a proper teacher. This section only serves to show you that there are things in post production that you can do if your photos aren't quite to your liking. Let's start by going to Select. In fact, let's just try select "Subjects" see if that works for us. Pretty good, that'll do for now. I wanted to duplicate layer. All right, let's mask that. Let's set that off for now and then on our background layer, we're just going to remove our subjects. Let's go again select "Subjects." I did a pretty good job. I'm just going to expand this a little bit just to make sure that we're not getting any of that hair left behind. I'm going to expand for quite a long while. It's got a 30 pixels and then I'm going to Edit, Fill and use Content-Aware fill. It's going to do a pretty bad job because the background's very busy. Yeah, it's pretty useless, but that's going to be okay. That's good enough because I'm going to put my subject back right in front of it. Let's select all, Filter, Blur, Lens Blur and then I'm just going to play with this Radius slider. The haloing of the hair is a little bit problematic, but if we increase this radius enough, it'll probably be nonexistent. You can see it's barely existent now. Press "Okay" and then put our subject back on. Suddenly, you got a really nice portrait. That's just a super quick and easy edit that you horribly improve upon. But it just goes to show that even if you've taken an image with a tiny sensor camera or your phone, or a very, very slight lens there's actually quite a lot that you can do in post-production.
15. Technical note on 'bokeh': Just briefly, let me touch on bokeh. I've used the term bokeh fairly liberally in this class. But on a technical level, bokeh actually refers to the quality of the out-of-focus areas in an image. If you look here, for example, in this image, you get these creamy backgrounds. For the most part, I wouldn't really worry too much about bokeh. Different lenses will render the out-of-focus areas differently. The appearance of these spheres, these bokeh balls they're often called, might be different from lens to lens. In this lens, it's pretty good. They're quite controlled, they're nice and round, and the balls are fairly consistently opaque. In some lenses, you get this onion ring effect, and in some other lenses you get a cat eye effect and the bokeh balls aren't very rounds. Just be aware of that, but I wouldn't worry about it too much. In this image, for example, you get some of that onion ring effects where the opaqueness of the bokeh balls isn't super consistent. In this bokeh ball, you don't get full roundedness, and you get a bit of distortion in some of these bokeh balls where they're not fully round. It's good stuff to know, but I really wouldn't worry about any of it.
16. Wrap up: Well, that brings us to the end of our class on portraiture, background, and bokeh. I hope you've learned a little bit and I hope I haven't bored you too much. I hope that I've made it clear that you don't have to have the most expensive [inaudible] the world to get that beautiful portraiture look. If you have any questions, just let me know. I'd love to answer any questions that you might have. See you next time.
Hugh White, Photographer, filmmaker and writer
