smartphone cameras are the most widely used least well understood piece of technology that I think I've ever seen they're the single thing that every tech company spends the longest talking about whenever they launch a new phone I mean there are memes at this point that phone reviews now are basically just camera reviews so I think it's time we sit down and we understand them by the time you finish this video you will not just get exactly how your smartphone camera Works what on Earth these companies are talking about with presentation slides like this and because of that also just to be able to use your phone to take the best photos you've ever taken so how does a camera work well imagine right now that you're standing in a room with no windows no doors no lamps what do you see you see nothing unless there is light your eyes are functionless you'll only see something if you pull out a torch and you shine it around and that's because the torch is going to be sending out light that's hitting things and then getting bounc back into your eyes the same is true for cameras what the camera sees is the light being reflected into it but in most cases light is bouncing around in every single wit way all at once so to make sure you're getting light information that's actually useful and not just a blurry ha you also need a lens a layer that takes all the light rays bouncing around and redirects them to meet at a single focused point on the inside that can record that information your eyes have a lens that focuses the light onto your retinas and in the exact same way your cameras have a lens to focus the light onto their way of recording that light information and what's that well early cameras had film which you can think of as light sensitive material where the pigment will effectively change based on how much light comes through the lens and hits each part of it now obviously if you left the film exposed to light for long periods of time you would just end up with the whole thing having reacted to it and just being a white sheet and that is why you also need a shutter you know this sound right this is the sound of an old school camera shutter which will quickly open and close when you took a photo to expose the film to light for just the right amount of time I'm telling you this because even though cameras have come a long way from the days of film The Core mechanism has not changed nowadays with digital cameras and phone cameras that film is basically just replaced for a camera sensor which instead of chemically reacting to light and being a one time time us thing can digitally react to light record what it's just seen and then ready itself for use again and again and you might be thinking well I definitely recognize that shutter sound but I've never actually seen a shutter physically opening and closing on my phone camera well that's because the other cool thing about using a digital sensor is that while you do still technically need a shutter to make sure that you start and stop capturing the light information at the right times it no longer needs to be a physical mechanical shutter the sensor itself because it's electronic can just decide how long it wants to collect the light 4 effectively becoming its own shutter and this obviously is a silent process so the shutter sound that you hear on your phones is I hate to say it a sound effect and that takes us to now now that we understand how the camera works it's time to talk about the smartphone camera because this is where things get weird I mean for starters one of the biggest questions you might have is why do I have two or three or four it's not like you ever see a proper camera with that many lenses on it that would be cool well fundamentally this is how smartphones achieve lens swapping if I want to swap the lens of my camera I do this I unscrew it I grab the lens that I want to replace it with and I literally just screw it in and swapping lenses is really important because different lenses give you different viewpoints like this right now is a wide lens so if I hand that to you Josh you can see it's not very flattering you can see the mess in the room and more importantly your focus is not really on my face so if you pass that back let me swap that out to a more narrow lens wide lens off narrow lens on now I hand that to Josh do you see how much more direct that feels really like we are in the same room having a conversation but there's a lot of reasons why this whole interchangeable lens thing it doesn't work on a phone very few people are going to want to carry around a pocket full of lenses having a detachable part like this is going to make it way harder to fully waterproof your phone and also are you going to take that lens off every time you put your phone away in your pocket I mean this hasn't stopped companies from trying but I think they're trying knowing that it will never be for the masses and so what's had to be done on the smartphone is multiple cameras multiple completely separate independent cameras each with their own separate sensor just so you can have different lenses available to you when you want them so when you're in your camera app and you're clicking between these various magnifications I know it feels like you're zooming in and then you're zooming out but really you're flicking between these very separate cameras with just some very sophisticated software that makes it appear much more seamless than it is now to be very blunt this is I it's kind of a waste of space the fact that we have to have three separate camera sensors just so we can have the thing that we actually want which is three different lenses is incredibly inefficient it means that phones will cost more than the otherwise would and also that each individual sensor has to be smaller and the smaller the sensor the less good they're going to be but the thing is for the time being there is no other way so what are these different lenses actually well aside from the primary camera there's two types of lens that we tend to see again and again on phones the first is the ultra wide which tends to be the best way to capture everything that's happening in a room at once as well as on most phones the best way to take a macro photo macro essentially means extreme closeup and just the way these Ultra wides are built gives them a much closer focusing distance than your main camera which is why with most Flagship phones when you bring them near to something you should notice that little lens shift as the phone moves from its main cam to its Ultra wide and then you've got the other key lens the telephoto which I would genuinely say is the most misunderstood lens so you might have heard for example that the iPhone 15 Pro Max has a five time zoom lens and that the Samsung has a 10 time zoom lens well that's not technically true let me show you so this is a zoom lens and so if we stick this onto our camera what it allows us to do is to rotate this ring and physically move the glass on the inside of the lens to increase the distance between the glass and the sensor this magnifies the image and this kind of magnification achieved by physically moving the lens or Optics of your camera is called optical zoom and why professionals like it is that it Zoom without a hit to Quality when you zoom like this the entire area of your sensor is still being used to capture information it's just that your lenses are changing what information is coming in and being delivered to the sensor it's kind of like when you're using a magnifying glass it's not reducing the quality of what you can see it's just enlarging it so that you can see it clearer okay so you might be getting where I'm going with this the zoom lens on your smartphones then that lets this iPhone get say five times magnification is not actually a zoom lens people call it that because it's easier to understand but really this is a tel photo lens meaning that while it is zoomed in so the lens on this camera is set in a way that it's far enough away from the sensor that it's magnifying the image five times Apple's achieved this with multiple mirrors that basically increase the distance light has to travel and while it is Optical magnification because the magnification is achieved by the position of glass without a hit to image quality what you can't do is change that magnification there's no room in a smartphone for the mechanism required to be able to shift the glass physically further and closer to the sensor like you can with this lens here I mean Samsung did try it but what it ends up with is your phone looking like a camera and so really your smartphone does not have an optical zoom camera it's fixed as are all the cameras in your phone so what does that mean in practice well basically that if your phone has three cameras then there are three specific magnifications that it's designed to work best at most likely one of those cameras will have an ultra wide lens on it which means that that camera will be the one that's active and at its sharpest when you're on the widest possible setting that your camera can go to but then as you zoom in your lenses are fixed so they're not moving what's happening instead to achieve that enlargement is digital zoom and this is not as good because it's basically the equivalent of me taking this shot at 0.5 time magnification the widest cropping into the photo like this and then saving that as the new image you'll have lost a lot of quality because when you do that what you're effectively doing is starting with a good base but then chopping off the top bottom and sides and keeping what's left but as soon as you hit one times magnification your phone will switch over to its main camera and then as you keep zooming up until the point where you hit your phone's telephoto magnification you'll switch from your main camera to your telephoto here's a cool way that I like to think about the quality of the images your phone will shoot as you zoom in more and more you start off solid with your Ultra wide camera but this tails off even with slight magn ification since it's not the best quality camera as soon as you hit one time your quality jumps dramatically to the highest quality that you're going to get out of your smartphone since your main cam almost always has the largest sensor given that this is always your best camera as you zoom further your quality does fall but just not as fast as it did with the ultra wide until it gets to the point where it starts to feel questionable and it's around at this point somewhere between three times and five times that most phones will switch to their third camera the telephoto which will be the only camera used from this point onwards so basically the further you go after this the more your quality will tail off that covers most flagships the only one that's significantly different would be Samsung's flagships since they have two telephoto lenses one at three times and then another one at 10 times so for these phones you'd basically just see an extra quality bump when you hit that 10 times number now with early smartphones it was really obvious when this camera switching was occurring you'd basically stop and wait while it was happening but nowadays it happens so smoothly with most phones that it's easy to completely not realize have a look at this as we're going back and forth between the 0.9x and 1X magnification the only way to really tell that we're actually moving from the ultra wide to the main camera is the very slight jumping movement of the objects in the frame why is that happening well because technically every single time we're fiddling between those two numbers we're jumping from a camera that's here to a camera that's here so while you're unlikely to notice this movement when you're shooting a vast landscape you're very likely to notice it when trying to focus on something close where small distances will matter more like when you're switching to a macro shot and that brings me on to something that we started constantly hearing phone companies talking about but what I think loses a lot of people focal length I mean really focal length is just a fancy way of talking about magnification but think of it like a universal way of comparing magnification between cameras so while three times zoom on this might mean something very different to three times zoom on this if I say a photo was taken at 55 mm then anyone can really understand what I mean by that so most smartphone cameras which have an ultra wide lens they start at around 13 mm your one times main camera will be around 24 mm and then on this phone which has a five times optical zoom your telephone to camera is 120 mm the reason that photographers like talking about things in terms of focal length is that different focal lengths create images with a different aesthetic this actually a really cool graphic that shows how the look of your photo changes with the focal length so these ones here are taken standing really close but using a really wide lens and they feel very imposing and very direct and then these ones here are taken from really far away but using a powerful telephoto lens they feel more proportionally correct and to me at least aesthetically pleasing okay that's all the basics of phone cameras covered now just before we get to the really fancy stuff I want to make sure that you understand every single stat that companies like to brag or talk about okay so first of all is resolution a camera's resolution is the total amount of pixels on the sensor the think of each pixel as its own individual unit on that sensor that every time you take a photo will be assigned its own exact color so in a simple way if we had a camera sensor with a 4 pixel resolution its photos would look like this if we then made it a 16 pixel sensor you get this and so on the more pixels you have the more detailed your image can be because you got more points of information being registered but it's not as simple as that see imagine that the main camera sensor on your phone right now let's say it's this big if you use a sensor this tiny to take a 200 megapixel photo that's 200 million pixels by the way imagine how tiny the surface area of each pixel is going to be you're very likely to face a different problem in that situation that while yes you have so many points on the sensor each registering information the amount of light getting to each individual pixel is also now so low that the quality of that information might well be garbage there's no use having 200 million pixels if each pixel is getting in such little light that it doesn't know what it's meant to be and is effectively just noise and so what most phone cameras do instead is something called pixel binning which is basically grouping together clusters of small pixels to make them more reasonably sized again so that each pixel is at least a quality pixel this is why the iPhone even with its 48 megap Main camera only takes 24 megapixel photos by default and why Samsung with its 200 megap Main camera only takes 12 megapixel photos by by default in a way this is smartphone makers just trying to solve the problem that they've created by trying to cram too many pixels into a tiny space so resolution is a bit of a sore spot it's not a useless stat it's actually a very important aspect to your images but it's just very easy to manipulate to make your phone seem better than it is what's much harder to manipulate though is sensor size and so that's the stat that over the years I've tended to pay the most attention to if you kept all other things the same and you just increased your sensor size there would basically be a direct uput correlation to image quality because with the same number of pixels but spread across a larger area each pixel is bigger gets more light and so is less likely to be noisy and then the thing that sits in the background of all this helping each of these other elements to achieve their potential is the stabilization system early smartphones use something called electronic image stabilization which is essentially imagine this is what your camera can see when using electronic image stabilization your phone is going to crop into that Total Image lose a little bit of quality but gain the ability to even out your hand movements so if your hand sudden suddenly jerks down a bit your phone will move a little bit up within that image to reduce the impact of that downwards motion then Optical image stabilization came in which is where the Optics of your camera I.E the lens physically moves to do the exact same thing that electronic image stabilization did but without that hit to Quality this has evolved on some Modern phones to something called sensor shift stabilization but it's kind of the same thing it's just the sensors moving instead of the lens but the key takeaway is that modern phones basically use a combination of both Optical and electronic this is why when you move from photo to video on your phone it tends to zoom in a little then you've got aperture which controls how much light your lens can let in It's actually kind of shocking how similar the camera is to the human eye because yes this is exactly what the irises in your eyes do by dilating or constricting your pupils you'll never stop noticing this now but if you ever stare into someone's eyes on a bright sunny day their pupils will be way smaller than if you stared into their eyes at night now a lot of real camera lenses that you control your aperture by turning a dial and check this this is what my camera looks like with a wide aperture and this is what it looks like with a tiny aperture like a pinhole but most phones kind of like the whole Zoom thing have fixed apertures and that's fine cuz I mean there are times where you might want to restrict light but largely speaking especially on a smartphone camera where you're already fighting to get enough light in you really just want your aperture to be as wide as possible the thing that does throw a lot of people off though is the aperture counts backwards so an F2 aperture is wider and lets in a lot more light than an F4 aperture and so in most smartphone use cases would be the preferred option and a sub to the channel would be apertur rfic so if you understand all of that we're basically there and we just have to talk about the computational aspect of smartphone photography now early phones were very simple what you see is what you get but two things have happened over the years one that companies have really started to push the optical envelope to its limit meaning that if we continue trying to make our phone cameras like we make our camera cameras then we can't really improve them any further without making a massive camera bump and inconveniencing the people who don't want that but then twoo at the same time as the optical development has slowed down the intelligence of phones has not meaning that more and more they have the Headroom to be able to understand the images that you're taking and enhance them using machine learning so here are some of the coolest ways that they do that HDR or high dynamic range is one of the most noticeable examples while with most non-smart cameras when you take a photo you take one photo with most modern smartphones when you take a photo you're actually taking between 9 and 15 shots on that camera depending on the exact model so with low exposure some with medium exposure some with high exposure matching them up to each other and fusing them together into the final it's kind of like when you tap on your screen and then scrub down to reduce the exposure and then you raise it to increase the exposure but just many times very quickly one after each other it makes a photo that would look like this or like this into a very balanced looking shot like this but what's actually even cooler SL kind of creepy is that a lot of top tier phones now they go a step further by starting to capture these buffer images silently in the background as soon as you open the camera app basically so that they're not saving all the work for that one moment where you click the shutter button cuz then it would take too long to capture portrait mode is a big one it's the modern smartphone's way of using computation to get around the fact that they don't have massive sensors when you take images or video with big sensor cameras you get this very distinct mix of a crisp foreground and a blurry background we've come to just associate this with the feeling of cinematic and so to try and recreate this phones started off by using the fact that they had two different cameras that were set L apart to look at the world and estimate depth if you close one of your eyes your depth perception you'll find it goes right out the window and so being able to estimate at least how far away things are from you allows you to simulate how blurred out they should be if you were filming on a bigger camera sensor and this has just got better and better over the years thanks to a specifically built depth sensors that can not just guess but actually measure how far away things are and B improved artificial intelligence that doesn't just take what the phone captures at face value but Combs through the image afterwards figures out that the subject is say a person and then uses what it knows about people to try and make sure that every strand of hair is perfectly accounted for and doesn't disappear into the background face unblur is actually even more fascinating it's something that I would say the Google pixel is leading the pack with and it figures out when your phone is moving a lot and so there's a high risk of a blurry face and it starts automatically capturing with the ultrawide camera as well as your main camera because the ultra wide camera is ultra wide it's less sensitive to movement and more stable so it can still in most cases get a lot of the key details of the shot sharp and then fuse those back into the main camera shot that you were taking but arguably even more advanced than all of that is night mode which for phones like the Google pixels is a lot of things at once to try and maximize detail in times where the available light information is very low it's the taking and stacking of multiple images like what happens with HDR it's fusing long exposure shots which keep the sensor registering information for longer to get more Li in and reduce noise and short exposures to quickly get the core structure of the image without motion blur and nowadays you don't even need to select night mode your phone will make all of these decisions for you it'll use its image sensors to figure out how dark it is and then its gyroscope to figure out how still it's being held which determines how long it can afford to keep its long exposures going for without risking blurring the image and phones now are even using something called semantic segmentation to apply different types of these processes to not just different images but different parts of the same image so the sky in your photo might well be going through a completely different processing pipeline as the tree so to bring this all together while the fundamentals of the smartphone camera are not too distinct from the fundamentals of a DSLR camera every year these tech companies are deviating further from it with all this computation and while that is amazing for so many key reasons like we've gone through the key downside I would say is that now there is almost no way to tell if a phone camera is going to be good based on its spec sheet as much as I hate to admit it cuz I love comparing Hardware these slides are borderline pointless nowadays I mean the Google pixel for example used the same main camera sensor for four generations in a row from the pixel 2 to the pixel 5 and yet with each generation through 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