8 Key Points to Understanding ISO and Image Quality
In this video we're going to talking about eight key points I don't know why I held up five that's five this is eight c I can count very well a key points toe better understanding so and in particular how I s o relates to image quality so let's start from the top key point number one and this is going to be a review for everybody because I expect that you've already understood and mastered this concept you're s o is the camera's sensitivity to light okay, so you raise the iso your sensitivity increases now we basically used so in situations where well the combination of shutter speed and your aperture doesn't yield the correct exposure you don't get enough light it could be because you need a closed down apertures that you get better depth of field it could be because you need a faster shutter speed or combination of both either way you're not getting enough light so we bump up the iso to compensate to increase that sensitivity toe light now more specifically it's not actually the came...
ra's sensitivity to light it's actually the camera's sensor if we're talking about a digital slr like this one okay, so we're talking about the actual sensors sensitive delight but if we're talking about a film camera then we're talking about the film's sensitivity toe light so when you go out and purchase film you're looking at the film's iso rating not the cameras cameras don't have an eyesore eating just the sensor or just the film. Okay, so we know this is so is the digital, or is the sensitivity to light either for its adolescent lars sensor or for film? Great let's, go on to key point number two. Number two is to understand that every bump up in iso is going to basically introduced grain into your image is going to do a couple other things as faras image quality, which we're gonna talk about. Keep one three as well, but that grain that it introduces is going to read reduce image detail. Now, I have a perfect little example here set up for you. So we're here in light room. And what I want to show you basically is that we took this exact same image with a cannon sixty mounted on a tripod, and we shot these cupcakes with different iso settings. So let's, look at these full screen so we can see each one of them. I'm gonna hit eyes. We can see our information. We have our first image here at s o four hundred, and then we go upto ezo sixteen hundred and then we go up tio s o sixty four hundred, and then we go up to twelve thousand eight hundred now the differences between these images is actually relatively difficult to see. But what we do notice if we zoom in is that we're starting to introduce a little bit of grain and that grain is actually real moving image details. So let's, say, for example, if I were to select these two and I'm gonna compare them side by side so we have four hundred left and we have is a twelve thousand eight hundred on the right. Take a look at this. We have a lot more smooth and consistent detail within this image, whereas in the one on the right we can see we kind of have this little blotchy nous. We have reduced overall detail in the image with that increase in iso. Now, the great thing about cameras today is that you can step them up to sixty, four hundred twelve thousand eight hundred eyes, so even beyond that on a seven s goes into, like four hundred thousand I also not necessarily usable, but at twelve thousand eight hundred, I'd still say that this image is usable if you have to shoot with that aiso setting. It's usable I mean cameras air getting the point where they can see in the dark basically but just realize that every step up is going to introduce grain and that grain is going to reduce detail I have another extreme example I want to show you guys actually this is on a seven s and here you can see that there's three nights of sixteen hundred rebate we I don't even see hardly any noise it's which is really incredible because back on film and in the early days of digital slr sixty hundred is actually quite a bit and you would get a lot of noise but look at this it's it's almost perfectly it looks fantastic but look it s a one hundred and two thousand we can see a lot of that detail being destroyed and then sew for hundred thousand again this yields basically at this point I saw one hundred thousand forty thousand those air still unusable iso's at least in my opinion those really aren't good enough quality but on the seven s the sony is unless you can go up tio very high aiso numbers and still yield completely usable images which is absolutely fantastic okay so moving on a key point number three is that raising your iso is going to reduce overall color and dynamic range within your image is well this is another effect that it has over image quality now what exactly does that mean? Well here's one of the images that we captured actually during our chutes and I'm going to reset this out back to the original this is one of those scenes where we talk about often maximizing dynamic range within a single raw file and to do that to really maximize dynamic range you need to shoot in rock and you need to shoot at your lowest possible native aya so and we'll talk about native eyes on just a moment as well but what this does is what we're trying to do here is if you look at the history ram we've captured as much detail as possible from the shadows all the way up to the highlights we've captured everything at least everything that the sensor can possibly capture within that range if we raise the is so let's take a look at what this was shot at okay so this was shot at one hundred so if we raise the ice so to say two hundred eyes so maybe the camera's sensor is capturing twelve or thirteen stops of dynamic range in this image and we get all those shadows we get all the highlights in that image and we can take it and we do basically this to it where we make our final adjustment we pull up the shadows we pull down the highlights and get a nice balanced and tone mapped image but if I raised the so to say two hundred then we're going to leave off a little bit of that history ram we might be clipping shadows we might be clipping mohr highlights because the carom may not be able to catherine say thirteen stops have been a hammock range it may be only capturing twelve point seven stops when we goto is a four hundred we reduce it again maybe now it's twelve stops so eight hundred now it's at ten stops I sew sixteen hundred now it's at eight stops every step up we're reducing the amount of dynamic range that can possibly captured within one single image that means that if we're trying to create a nice beautiful landscape with an amazing range of color and tone well we need to keep it at the lowest possible iso it's also the reason why if you look at nighttime shots where you raise it up to say I saw thirty two hundred sixty four hundred you kind of noticed that the colors look a little bit dingy they kind of look a little bit well they just don't pop the same way that they would on image like this shot at the one hundred okay so just remember that again stepping up not only increases grain stacking of the isa will also decrease overall dynamic range all this talk about raising the esso decreasing dynamic range introducing grain and so forth kind of might dissuade you guys from increasing your eyes oh but it is absolutely necessary in many situations. And this is what I would say for key tip number four mikey point number four that is that raising the iso and getting your shutter speed up high enough where you get a sharp image is much, much better then keeping the isa lower and getting a blurry image. So, for example, this image right here, this was shot at one one sixty of a second, which gives us just enough sharpness to keep our couple sharp and in the shot, while also introducing a tiny bit of motion in, like, kind of the little pedals that they're throwing across the frame. We could even slow down a little more if we want to get more that motion. But let's, say, if I kept this s o a hundred, that would mean that I need to reduce the shutter speed down to something like, well, let's. See, if we go from thirty, two hundred to six hundred down to eight hundred, we'd be going from shutter speed of one sixty down, tto one eightieth down, tto one, fortieth and at one forty of a second. Yes, we might get better color. Yes, we might get better detail, but then we yield a blurry image, a blurry image that would be unusable. So this is my point, is that our digital cameras, they're fantastic. You can raise the iso up pretty high. Going up to six hundred thirty, two hundred. It's. Totally fine. Getting a sharp image. Getting a usable image is always going to be more important than making sure that you have perfect detail and absolutely perfect color and dynamic range and so forth. So understand the situation and know when it's totally appropriate. And when you need to bump up the highest. So now, key point number five that I wanted to bring up is that a lot of you will think that. Well, maybe it's better for me to shoot at a lower is so. And then basically get a slightly darker image and raised up in post rather than raising the iso in camera. That's. Definitely a bad idea. I'm gonna show you exactly why in general let's. Go back, teo. Just this whole view right here. I have two images right here that want to demonstrate with so you can see here that one was shot at thirty seconds f four, four hundred and thirty seconds f four s o sixteen hundred. Now, this is a to stop different. So going from four hundred to eight hundred to six hundred deaths, two stops, yes. That is two stops so what if I shoot a darker over here like because I wanna yield better dynamic range and better detail and so forth and I was brighten it up in post to get a better look? Well let's try that you're going to find out that basically by doing this you will actually get worse dynamic range worse color will and especially worse detail by raising the exposure significantly in post okay, so on the left we have our image shot at sixteen hundred aiso and on the right we have our image shot at four hundred esso and we've raised the exposure by two stops to match it in postproduction let's go lights out by hitting l if you're in light room where we're going to a zoom in now to this image and check this out the image on the left at the higher so in camera yielded a better image than the one on the right where we shot it at a lower aiso and then raised it digitally in post so we have more grain over here I seem or color noise where basically have these kind of variations in color that don't look good going into the shadow we can see that we have maur banding mohr noise inside of the shadows we have all these issues where's the left shooting at the higher native so in this camera gave us a much better image than basically, just trying to raise it in post, so that is key tip number five do not shoot at a lower iso expecting to adjust in post and get a better image by raising your exposure in postproduction, you're always better off raising in camera to the net ex native aiso level that gives you a correct exposure than trying to do it in post, and that leads me perfectly in the key point number six, which is what the heck is native eso I've said native, I s o many times, and I will probably say it many more times. So what is they divide? So will every camera, and this is a cannon finding mark three whether you're on a rebel weather on the five mark three, whether you're on a d a hundred, whether on a sony camera, every single camera has what's known as an native eso for this camera for the cannon finding mark three, the native aya. So when shooting stills, I saw one hundred. This means that basically every stop, every full stop from that native I so is a another native iso number. So what does that mean? Okay, so if we go from one hundred two, two hundred that's in a device so two hundred four hundred that's needed by so four hundred eight hundred that's in a device so eight hundred six hundred and so forth the in between numbers are not native is own numbers so for example is a one sixty I so three twenty s o for whatever those in between numbers are not native eyes those and so what essentially happening is that if you shoot at a number like that the camera's actually shooting at is a one hundred and it is digitally modifying it to bump it up toe so one sixty or whatever you're shooting at so the camera's actually digitally brag ning these images which will yield worse results then if you step it up to the next higher so so for example I would actually get a cleaner image shooting at s o two hundred and darkening it down a little bit versus isa one sixty okay, so keep the camera at least we'd recommend keeping the camera at the native iso for every camera is going to defer for example on a lot of nikon cameras they start natively is so two hundred so I saw two hundred, four hundred eight hundred some cameras there is a one sixty native so it be isa one sixty three, twenty six, forty and so forth just learn your particular camera and we'd recommend sticking with those native iso numbers just for best image quality now is going to be a huge massive difference well no, but it will give a little bit of a difference in image quality and when you're actually looking in and pixel peeping it's actually quite noticeable okay now moving on to keep on number seven is that I would recommend leaving your eyes oh adjustment as the last step in the exposure equation so for example, you go into a scene and you choose a shutter speed that fits the type of action and whatever it is that you're shooting or you pick an aperture that matches the type of compositional feel thatyou wantto have at that point then decide what you need your eyes so to be so don't rely on eyes so don't just set the iso at four hundred and go out anywhere and start shooting because you really are kind of reducing image quality in a lot of situations that aren't necessary for example, I know a lot of shooters that built leave their camera sound is a four hundred and they'll shoot outdoors the entire time just with a left on faisal four hundred because they're worried about when they go in the shade they might not have enough light, but then when they go back in daylight they'll have you know too much and they figure it doesn't really matter you're better off just adjusting and each scene that you need to so leave that as the last part of the equation because why would you want to reduce image quality just directly from the camera? Finally key point number is that you can use s o for creative effect but my guidance would be to be extremely careful okay, now let me show you exactly what I mean let's go backto like graham and I have two example images right here was going to bring them up in survey mode now these images were shot on our rebel there shot during the course of this workshop and a lot of photographers when they go out in this kind of situation and mohr experienced photography but ours will go in and say I'm going to shoot this at s o four hundred eight hundred because it's going to yield a less digital image digital cameras at one hundred s o I mean they can capture so much details so much dynamic range that it it almost looks digital in a sort of way and I want one hundred percent agree with that. So what they'll do is they'll step it up to isa four hundred or so a hundred and they'll shoot a scene like this at a higher so which is going to decrease the dynamic range and add a little bit of grain and noise and kind of reduced with the color and it makes it look kind of like it did back on film and that's great! It makes for a very natural filmic effect, but what I would say is if you are an advanced photographer and you have a grasp of everything and you understand this, then find by all means go out and do it. But there is a giant warning with that because when you go out you shoot images like this in daylight if at a later point in time you say that all man, I really wish I had more detail me shot that really which had more color in these shots you can never go back if you shot these s o four hundred whether you shot rot or j peg that's not something that you can undo it's always going to be a iso four hundred and the detail you capture is the detail that you have if I want to introduce grain and kind of a filmic look in post I can do that I could do that with like him I could do with capture one I could do with photo shop I could do and it's fairly simple to do and there's also pre sets out to help you to do it as well, but if you do it in camera and you further enhancing post will whatever you've done in camera cannot be undone so that as my warning there and that's kind of why I'd say I would recommend against using it as a creative effect in camera, because you can always add filmic effects later. But you can't take it away if you did it in camera. So if you absolutely one hundred percent know that this is what you want in, you're okay with those images being that way forever, then pile means used eso for creative effect. Otherwise, again, levi's oh is the last step in your creative exposure equation, and use it simply to just get to the correct exposure. That's it for this video on iso. Hopefully, this has helped you all to better understand esso and how it relates to image quality and, well, I'll see you all in the next video.