Speaker 1: Get in touch with technology with tech Stuff from how
Speaker 1: stuff works dot com. Hey there, and welcome to tech Stuff.
Speaker 1: I'm your host Jonathan Strickland. I'm an executive producer with
Speaker 1: how Stuff Works in I heart radio and I love
Speaker 1: all things tech, and today we're going to take a
Speaker 1: close look at how image sensors work in a classic
Speaker 1: episode of tech Stuff. This episode originally published on February
Speaker 1: twenty nine, two thousand twelve. It is called how Image
Speaker 1: Sensors Work, and we're talking about the various sensors that
Speaker 1: you would find in digital cameras. So I hope that
Speaker 1: you enjoy this classic episode as Chris Palette and I
Speaker 1: tackle this topic. So today we thought we would look
Speaker 1: at something. Actually it was Chris's suggestion that we look
Speaker 1: into this particular topic, which was the the topic of
Speaker 1: image sensors and what they do and what the two
Speaker 1: main types of image sensors, how they are different from
Speaker 1: one another, and uh and I thought it was a
Speaker 1: great idea. It's also a fairly complex topic. We do
Speaker 1: have an article on how stuff works dot com that says,
Speaker 1: what is the difference between c c D and CMO
Speaker 1: s image sensors in a digital camera? And that's really
Speaker 1: what we're gonna be talking about here. Um. So that
Speaker 1: there is an article on the site, and that's a
Speaker 1: nice short article if you want a quick overview, but
Speaker 1: we're gonna go into some detail a little bit in
Speaker 1: this podcast. And really the first thing you need to
Speaker 1: know is that an image sensor is it's taking the
Speaker 1: place of film, right, Yes, that's correct, Yeah, a long
Speaker 1: and a long time ago in a galaxy that happens
Speaker 1: to be right here where we're sitting. We did a
Speaker 1: podcast on the megapixel myth um. I think a lot
Speaker 1: of people equate uh, numbers with a way we have
Speaker 1: with quality and they say, oh, well, I've got a
Speaker 1: twelve megapixel camera that's obviously better than that six megapixel
Speaker 1: camera I used to own. Well, it depends on what
Speaker 1: you're doing with the photo. It also depends on again
Speaker 1: the other qualities of that camera, right, and image sensors
Speaker 1: have a lot more to do with the quality of
Speaker 1: the photo. But in a way it really depends because
Speaker 1: again this uh there, there's this this idea that there
Speaker 1: are two different kinds, which kind is better? It depends
Speaker 1: on what you're doing with that what are you taking
Speaker 1: photos of? Um? And Uh, As it turns out they're
Speaker 1: they're not really better than one another. Inherently, they're they're
Speaker 1: better than one another for specific applications of the photographic technology,
Speaker 1: and the quality of the two sensors is constantly getting
Speaker 1: closer and closer, so that the things that one sensor
Speaker 1: does better than the other start to become less distinct
Speaker 1: over time because the technology is improving on both sides simultaneously. Uh. Now,
Speaker 1: if we were to go back a little bit to
Speaker 1: the early days of digital cameras, the distinction was was clear.
Speaker 1: You know, you would say that, well, a professional photographer
Speaker 1: would more likely have a cc D image sensor in
Speaker 1: his or her camera. CCD meaning charge coupled device, charge
Speaker 1: coupled device, that's that's one of the two types. And
Speaker 1: someone who has say a relatively inexpensive of course, back
Speaker 1: in the early day of digital cameras, that was definitely
Speaker 1: relative eight billion dollars, only a thousand dollars, yes, princely
Speaker 1: going back to that a thousand dollars as opposed to
Speaker 1: say eight thousand dollars. But a person holding one of
Speaker 1: those cameras might have a CMOS or a complementary metal
Speaker 1: ox side semiconductor image sensor. Yes, they come up and say,
Speaker 1: that's a wonderful shirt you're wearing today. That's that's such
Speaker 1: a great picture you've taken. Have you lost weight? No,
Speaker 1: it's not that kind of complimentary. I have a whole
Speaker 1: joke about that, but I'm going to spare everybody because
Speaker 1: we've already said the punch line. Anyway, these are the
Speaker 1: two different sensors, and they do go about capturing data
Speaker 1: a different way. Let's let's go into the basic way
Speaker 1: a camera captures an image. I'm going to talk about
Speaker 1: still camera here, so we're talking about cameras in general,
Speaker 1: not necessarily film, more digital. Right, So, in general, what
Speaker 1: happens is you've got a camera and you're pointing it
Speaker 1: at something that you want to take a photo of.
Speaker 1: Light is coming towards you. It's reflecting off of the
Speaker 1: the subject of your photo. If light we're not reflecting
Speaker 1: off the subject of your photo, it would either mean
Speaker 1: you were in total darkness, in which case taking a
Speaker 1: photo is not very helpful, or you're taking a picture
Speaker 1: of a black hole because not even light can escape it.
Speaker 1: That being said, they're actually looking at making a physical
Speaker 1: picture of a black hole. Using radio telescopes, which is
Speaker 1: so cool. That's the tangent. Anyway, so light is coming
Speaker 1: from the subject a little bit is awesome. We should
Speaker 1: do a full podcast us on that. But anyway, lights
Speaker 1: coming from from the subject toward the camera and uh,
Speaker 1: and the light passes through the lens. The purpose of
Speaker 1: the lens is to focus that light toward a specific
Speaker 1: point within the camera. It moves through the aperture, which
Speaker 1: is the opening behind the lens that allows light to
Speaker 1: pass through. There's a shutter that's there behind the aperture
Speaker 1: which actually directs the light up towards the view finder.
Speaker 1: For the old style cameras, you know, the ones that
Speaker 1: don't have the you know, you're not looking at a
Speaker 1: screen on the back, you're looking actually through a view finder. Well,
Speaker 1: that light gets directed up by a mirror and that's
Speaker 1: essentially attached to the shutter that makes the light go
Speaker 1: up inside the camera. Then it hits a prism which
Speaker 1: inverts the light. Because you may not know this, but
Speaker 1: the light the image that's coming in. That's saying the
Speaker 1: sensor is actually upside down from our perspective. Gasp. So
Speaker 1: if you didn't have that prism there, the subject you're
Speaker 1: looking at would be upside down. It would be like
Speaker 1: everything you're making photos of was in Australia. That unless
Speaker 1: you're Australian, in which case it's all in Detroit. So
Speaker 1: that's the that's the way. If you're wondering why there's
Speaker 1: all these giant car factories in Australia, it's not. It's
Speaker 1: just because you didn't have that prism in there, right, Um, Okay,
Speaker 1: that's a terrible joke, but no, the prism does invert
Speaker 1: the light, so otherwise again upside down. So when you
Speaker 1: press the button to capture an image, the shutter, the shutter,
Speaker 1: the shutter release exactly, the shutter, the shutter moves out
Speaker 1: of the way and instead of the light hitting that
Speaker 1: mirror and going up to the prism and inverting, the
Speaker 1: light hits either film in a film camera or an
Speaker 1: image sensor in a digital camera. So really the shutter
Speaker 1: just moves out of the way and then the light
Speaker 1: hits the sensor and then you're good to go. It's
Speaker 1: a little different with the digital cameras that are out
Speaker 1: right now, but that's in general how the process works basics. Yeah, now,
Speaker 1: and with cameras now, light maybe hitting the sensor constantly,
Speaker 1: and the shutter itself is not a physical shutter. It's
Speaker 1: just the way that the sensory captures data. And we'll
Speaker 1: talk about that when we get to that point. There
Speaker 1: are two different major types of shutters that we can
Speaker 1: talk about. So that's the general process. Now, with film,
Speaker 1: it's a chemical process. Light hits the film and then
Speaker 1: some chemical reactions take place, and that's what allows you
Speaker 1: to capture an image. Right. With image sensors, it's not chemical,
Speaker 1: it's electrical. Right, you're converting light energy into an electronic signal. Yes,
Speaker 1: and then you're gonna want to store to some medium. Yes, uh,
Speaker 1: you know, typically some kind of flash memory device, depending
Speaker 1: on on what kind of camera you have. You know,
Speaker 1: there were some I think that that stored on CD,
Speaker 1: so you know, your mileage may vary, but in general,
Speaker 1: some sort of flash device on onto day's cameras. Yeah.
Speaker 1: The old digital camcorders could record on on different kinds
Speaker 1: of media and so, and digital camcorders are working under
Speaker 1: the same general principles as digital still cameras, with some
Speaker 1: you know, other differences, but we'll talk about that. Like
Speaker 1: I said, so, now we get into the differences between
Speaker 1: the two major types of sensors, the charge coupled device
Speaker 1: and the complementary metal oxide semiconductor. So we're just gonna
Speaker 1: go do cc D and CMOS from here on out,
Speaker 1: I think, otherwise I'm just going to have tongue twisters
Speaker 1: for the rest of the podcast. Yes, well, I just
Speaker 1: wanted to make sure that people knew what it what
Speaker 1: it stood for, obviously very important. So in in a
Speaker 1: c c D sensor, every single pixel now, pixel, remember,
Speaker 1: is a point of light. An image is made up
Speaker 1: of pixels, millions of pixels. That's where the megapixel comes from. Right,
Speaker 1: So a twelve megapixel camera is going to take twelve
Speaker 1: mega pixels worth of pixels and within the dimensions of
Speaker 1: that image, whereas an eight megapixel camera will use fewer
Speaker 1: pixels for that same size. Right. But and that's where
Speaker 1: our idea about resolution comes in. Sometimes you hear people
Speaker 1: talk about a low resolution image, it may be that
Speaker 1: it's got fewer pixels in that image so that you
Speaker 1: can actually start seeing if if the pixels are large
Speaker 1: enough and few enough, you can start seeing the borders
Speaker 1: from one pixel to the next. It's not very smooth,
Speaker 1: it's almost jagged. Well, yeah, I mean that this is
Speaker 1: the benefit of having a high megapixel camera. If you
Speaker 1: shoot it high quality, then you are capturing more more
Speaker 1: pixels for a specific region of the image, and you
Speaker 1: can you can render that photo in a larger format.
Speaker 1: Um because when you shrink, when you when you compress
Speaker 1: the size of photo and reduce it in size um,
Speaker 1: the compute it or is able to you know, throw
Speaker 1: out unnecessary information and that the image still is pretty
Speaker 1: good looking. When you try to increase the size, the
Speaker 1: computer has to sort of guess on you know, pixel
Speaker 1: by pixel basis. Well, I mean, this color is sort
Speaker 1: of a brown color. It looks like I could throw
Speaker 1: something else in here similar. And that's why when you
Speaker 1: increase the size of a photo, a digital photo, that
Speaker 1: it starts to look kind of jaggedy and rough because
Speaker 1: the computer is having to guess at what that information is.
Speaker 1: So if you take a ten megapixel photo and shrink
Speaker 1: it down, it's it's gonna look pretty good. But if
Speaker 1: you try to take a two megapixel photo and blow
Speaker 1: it up, it's not gonna be so pretty. Yeah, if
Speaker 1: you think about it like a puzzle, Let's say that
Speaker 1: you have a puzzle that has four pieces to it, well,
Speaker 1: then you're gonna be able to see the division of
Speaker 1: those those four pieces very clearly. If it has four
Speaker 1: million pieces, then it's each of those pieces are individually
Speaker 1: much tinier than those four giant ones. That's the air
Speaker 1: issue is that the larger you blow something up, if
Speaker 1: it's if it doesn't have enough mega pixels in it,
Speaker 1: not megapixels, but enough pixels, then you're gonna start to notice.
Speaker 1: But that being said, the general digital cameras that are
Speaker 1: out there for the consumer market and the general way
Speaker 1: the consumers use digital cameras, megapixels really don't matter because
Speaker 1: most of us are not blowing images up to poster size.
Speaker 1: Most of us are using them for online photo albums.
Speaker 1: We might print a few out, but usually eight by
Speaker 1: ten tends to be about the largest because most people
Speaker 1: don't have printers capable of printing at a larger size,
Speaker 1: and when you take it to somebody to have it printed,
Speaker 1: it's kind of expensive, so a poster. Most of us
Speaker 1: don't do that, so most of us don't need to
Speaker 1: worry about megapixels at this point. Professional photographers, it's a
Speaker 1: different story. So cc D sensor, each of those pixels
Speaker 1: has a charge. The photons that are coming in and
Speaker 1: hitting that image sensor are being transferred from from a
Speaker 1: light energy from photons into electrons. Now UH, they have
Speaker 1: UH there's an output node with a c c D
Speaker 1: sensor where that is converted into voltage. It's buffered and
Speaker 1: then sent to a different part of the camera so
Speaker 1: that it will become an analog signal. So a CCD
Speaker 1: sensor it's a very it's a very UH specific device
Speaker 1: that doesn't it doesn't have a lot of other functionality
Speaker 1: to it apart from the fact that it's taking in
Speaker 1: light and converting it into voltage. UH. Now the pixel
Speaker 1: is completely devoted to capturing light and it has a
Speaker 1: very uniform output. So the that's that's sort of where
Speaker 1: the the idea of CCD being high quality came from. UH.
Speaker 1: It was very good at capturing the true essence of
Speaker 1: whatever it is you're pointing your camera at. You don't
Speaker 1: have to have a you don't have to worry about
Speaker 1: low lighting effects that kind of stuff, or having uh
Speaker 1: an image turn out too grainy if the light is
Speaker 1: too low, which can happen with CMOS images, particularly from
Speaker 1: a few years ago. It's a depending on where you
Speaker 1: know where the manufacturer for your camera got the c
Speaker 1: m O S sensor. Uh, you might not have as
Speaker 1: big an issue taking low lighting uh images. But if
Speaker 1: you've ever used a digital camera in a know, either
Speaker 1: a dark or just a dem environment, and you look
Speaker 1: at me like, this just doesn't look good. Now, when
Speaker 1: I take a photo outside in the middle of the daytime,
Speaker 1: it looks gorgeous, beautiful colors, very very distinct. Um. That's
Speaker 1: part of the problem is that the CMOS sensor captures
Speaker 1: it in a different way. In that case, every single
Speaker 1: pixel has its own charge to voltage conversion. The c
Speaker 1: c D, it's doing all of the pixels at once.
Speaker 1: In CMOS, it's doing each pixel individually. And then the
Speaker 1: sensor itself has other elements added to it that the
Speaker 1: c c D sensor does not have. Remember we said
Speaker 1: c c D kind of offloads the information once it's
Speaker 1: been converted into electrical impulses to other chips, right, Well,
Speaker 1: those elements are actually on a CMO S sensor. So
Speaker 1: it's got amplifiers, it's got digitization circuits, so it's actually
Speaker 1: converting the electricity into bits. On the sensor itself, it's
Speaker 1: got noise reduction capabilities, and so that means that it
Speaker 1: actually speeds up the process and it decreases the amount
Speaker 1: of space you need within a camera because all of
Speaker 1: those elements are found on a single chip as opposed
Speaker 1: to having dedicated chips for these these specific functions. Unfortunately,
Speaker 1: also reduces the amount of space it has for image
Speaker 1: capture because all that stuff is on the same chip. Yes,
Speaker 1: so that that you know, that's a downside, yes, so
Speaker 1: you that was one of the arguments again early on,
Speaker 1: was that c c D cameras could take sharper photos
Speaker 1: than CMOS cameras, and that you know, it's almost there
Speaker 1: was also an expense issue, right, c c D image
Speaker 1: sensors tend to be more expensive than CMOS ones CMOS.
Speaker 1: The process of manufacturer got so efficient that the price
Speaker 1: started to come down, and that that's why those are
Speaker 1: the sort of image sensors that you find in things
Speaker 1: like smartphones. You know, smartphones that have cameras tend to
Speaker 1: have CMOS sensors in them. They take up less space,
Speaker 1: they put out less heat, they take less energy to
Speaker 1: run um and they're very fast. So those are all
Speaker 1: the qualities that people who are having a who wants
Speaker 1: something in a nice slim form factor or if that's
Speaker 1: what's important to them. So yeah, C C D S
Speaker 1: image sensor might take a sharper quality photo in certain situations,
Speaker 1: but it's also going to require a larger form factor,
Speaker 1: and it does take more energy to run, and that
Speaker 1: that energy is going to also mean more heat. Yes,
Speaker 1: as we know, as electricity runs through a circuit, one
Speaker 1: of the by products is heat. We haven't figured out
Speaker 1: a way to get around that yet. It's just one
Speaker 1: of those one of those realities that it's uh um. Basically,
Speaker 1: it's inefficient enough where some of the energy is being
Speaker 1: converted to heat energy instead of you know what it
Speaker 1: is intended for. Right, Chris and I have a little
Speaker 1: bit more to say about image sensors, but before we
Speaker 1: get to that, let's take a quick break to thank
Speaker 1: our sponsor. So, so now we've got down to the
Speaker 1: the idea of these two different image sensors capturing uh
Speaker 1: information in different ways um, and the fact that over
Speaker 1: time both both types of sensors have developed to the
Speaker 1: point where the differences between the two, apart from the
Speaker 1: fundamental difference about how they collect information, have started to
Speaker 1: to diminish. Right, So that you can find some professional
Speaker 1: cameras out there now that you CMOS image sensors, whereas
Speaker 1: you know, a few years ago that was really unheard of.
Speaker 1: And you can also find some consumer cameras, especially in
Speaker 1: the cam Quorter realm, that are using cc D image sensors,
Speaker 1: which again for a while you just didn't hear about
Speaker 1: because c c D cameras were so expensive. It was
Speaker 1: pretty much reserved for professionals, you know, just consumers just
Speaker 1: didn't necessarily have the money to drop on something like
Speaker 1: that unless they were you know, one per centers. So yeah,
Speaker 1: it's it's it's it's still a developing thing and we're
Speaker 1: still seeing that kind of level out. But that and
Speaker 1: the two technologies do still exist. They coexist, so it's
Speaker 1: not like one has been abandoned on top of in
Speaker 1: favor of the other, although that tends to there there's
Speaker 1: usually someone predicting that every few years. Well sure, sure,
Speaker 1: um yeah. A lot of the research that I did
Speaker 1: for the podcast was from Teleedne Dolsa, which makes which
Speaker 1: makes both types of sensors, and they had some really interesting,
Speaker 1: uh comparative white papers and other information. If you're interested
Speaker 1: in getting into the depths of it, it got some
Speaker 1: of it got fairly complicated. UM. But basically they they
Speaker 1: had one paper they said that they're, uh that image
Speaker 1: sensors can be measured on basically eight different characteristics UM.
Speaker 1: And these were responsivity, you know, basically how responsive that
Speaker 1: the sensor is. Uh, it's dynamic range, uniformity, shuttering, UM, speed, windowing,
Speaker 1: and anti blooming UM. And you know, again this is
Speaker 1: kind of you know complex, but the the uh, it's
Speaker 1: kind of funny because the way that the image sensor
Speaker 1: captures information. UM. You know, depending on the type that
Speaker 1: you're talking about, they're not really uh, it's really application specific.
Speaker 1: UM some of them. Some of them really don't have
Speaker 1: that much difference over the others. Like, for example, UM,
Speaker 1: CMOS chips are known to be a little bit more responsive. UM.
Speaker 1: But c c D s are have an advantage in
Speaker 1: dynamic range. But basically they didn't say, you know, the
Speaker 1: this one chip is better than the others. They said,
Speaker 1: it has more to do with the manufacturing capability and
Speaker 1: whether the chip has done right and is used in
Speaker 1: their correct setting than it does UM, you know, for
Speaker 1: a particular type of technology. Right, and you were mentioned
Speaker 1: mentioning the fact that there are different shutters. In general,
Speaker 1: a CMOS image sensor uses a rolling shutter. Uh, there's
Speaker 1: nothing saying that it couldn't use the same sort of
Speaker 1: shutter that SEC the image sensor does, which is a
Speaker 1: global shutter. There's nothing saying that it couldn't. It's just
Speaker 1: that all the camcorders I looked at specifically, because this
Speaker 1: really plays more into video than than uh, still photography.
Speaker 1: Although there's some crossover between the two. Um it said
Speaker 1: that you could have a CMOS with a global shutter,
Speaker 1: it's just that you don't find those. So what's the
Speaker 1: between the global shutter and a rolling shutter? Well, a
Speaker 1: rolling shutter to me. And when I the first I
Speaker 1: read about this, the first thing I thought about was
Speaker 1: a copier or a scanner where the image sensor you
Speaker 1: put the document on the on the screen, you close
Speaker 1: the UM the top of the lid, and you tell
Speaker 1: it to go ahead and make a copy or make
Speaker 1: a scan of it, and the image sensor travels down
Speaker 1: the length of the document from the top to the
Speaker 1: bottom or what exactly, and and it is going you
Speaker 1: know from UM it's starting at a specific point and
Speaker 1: capturing the entire document as it travels the length of
Speaker 1: it and uh, you know, because it's going essentially line
Speaker 1: by line. If you think about that in pixel terms,
Speaker 1: is taking a row of pixels and then another row
Speaker 1: of pixels and then a nighte you know, as it
Speaker 1: goes down. Right, Yeah, I was thinking of it sort
Speaker 1: of the way television works. Yes, where it'll it'll you
Speaker 1: have a line by line from the top to the bottom.
Speaker 1: Um will ignore the interpalation part, otherwise we have to
Speaker 1: get really complicated. But anyway, the image is painted essentially
Speaker 1: on your screen from the top to the bottom at
Speaker 1: a rate that's so fast that your eye does not
Speaker 1: detect that. It looks like it's all simultaneously projected to you,
Speaker 1: but it's actually done line by line from the top
Speaker 1: of the screen to the bottom of the screen. Same
Speaker 1: thing with a rolling shutter. So when you take a
Speaker 1: photo or you're using a camcorder, let's stick with cam quorters.
Speaker 1: So if you're using a camcorder that has a rolling
Speaker 1: shutter type of image sensor talking cmos, uh, the the
Speaker 1: images being recorded from the top to the bottom over
Speaker 1: and over and over again. Okay, so uh with a
Speaker 1: c c D camera, it's a global shutter which means
Speaker 1: that it's capturing all that data all at once, Yes,
Speaker 1: sort of like film would. Yeah, so it's not it's
Speaker 1: not um you know, it's not something that's gonna be scrolling.
Speaker 1: It's all one image. So this means that the two
Speaker 1: different types of image sensors are also prone to two
Speaker 1: different kinds of flaws that can happen when you're using them. Well,
Speaker 1: of course, I mean that's that's like any other types
Speaker 1: of technology. Not everything is suited for every use, right,
Speaker 1: So let's say that let's i'll talk about the different
Speaker 1: flaws that you can find. C c D essentially has
Speaker 1: one type of flaw that you can encounter, which is
Speaker 1: called the smear effect. So smearing is let's say that
Speaker 1: you've got a a you're taking an image of something
Speaker 1: that has a bright light in it. Um Smearing is
Speaker 1: this effect where you sort of see the light. You'll
Speaker 1: see like a projection of light above and below it
Speaker 1: or you know it's that's that's why it's called smear.
Speaker 1: It's it's been extended beyond just a source of light itself.
Speaker 1: It's kind of like a halo effect, though usually it's
Speaker 1: more of at least in the samples. I've looked at.
Speaker 1: It's more of a vertical thing where it looks like
Speaker 1: it's almost like a ray of light that goes straight
Speaker 1: up and down the the the screen from the source.
Speaker 1: So that's one of the things that c c D
Speaker 1: image sensors can fall victim to, but not CMOS. And
Speaker 1: it's all because that global shutter exposes that image, the
Speaker 1: whole image simultaneously, and it's all gathering that light, and
Speaker 1: once the predetermined shutter speed for that global shutter has elapsed,
Speaker 1: it stops gathering light, turns that that entire exposure into
Speaker 1: an electronic image, and then starts again. And the rolling
Speaker 1: shutter just doesn't have that same effects, so the smear
Speaker 1: does not happen with that, and it's you know, it's
Speaker 1: very noticeable. If you see the the effects of this,
Speaker 1: you'd think, oh, well, that's unfortunate that there's this weird
Speaker 1: shaft of light right there in the middle of the frame. Well,
Speaker 1: that's that's it for the c c D. Okay, that's
Speaker 1: the that's the one flaw that's c c D image
Speaker 1: sensors can can fall victim to. But there's the one
Speaker 1: known thing that people complain, the one thing that people
Speaker 1: complain about. There are three three different ones for cmos.
Speaker 1: The first is called skew. Okay, So you've got this
Speaker 1: rolling shutter and it's going from top to bottom as
Speaker 1: it's recording images. Now, this utter is going off u
Speaker 1: multiple times per second. But let's say that you are
Speaker 1: panning the camera very very quickly from one side to another,
Speaker 1: so you're changing the view. Well, you're having a rolling
Speaker 1: shutter and you're panning the camera. This can cause the
Speaker 1: idea of skew. We have just a bit more information
Speaker 1: to cover in this classic episode of tech stuff, but
Speaker 1: before we get to that, let's take another quick break
Speaker 1: to thank our sponsor. So let's say that you have
Speaker 1: something that's uh, that's significant, a big thing that's in
Speaker 1: the frame of the photo, maybe maybe like a tower.
Speaker 1: All right, So you've got a tower in the frame
Speaker 1: of your image, and you quickly pan from left to right. Well,
Speaker 1: as you're panning, that shutter is rolling, and if your
Speaker 1: pan is fast enough, then the shutter is actually going
Speaker 1: to start building an image where the pixels at the
Speaker 1: top of the image are further on one side than
Speaker 1: the pixels that are at the bottom of that image.
Speaker 1: Because it's not capturing all that data simultaneously. The outcome
Speaker 1: of that is that you get a skewed image when
Speaker 1: the output image itself is skewed. So that tower, which
Speaker 1: might be perfectly straight when you look at it, when
Speaker 1: you start looking back at the video and you're playing
Speaker 1: it back really slowly, it suddenly looks like it's leaning
Speaker 1: or it's diagonal. It's like that, you know, it's suddenly
Speaker 1: not it's not true anymore. Now I understand what's wrong
Speaker 1: with all those vacation pictures I took. Yeah, exactly, that's
Speaker 1: the that's it. You know, it's no, it's not at all.
Speaker 1: But anyway, that's that effect is because of that rolling shutter,
Speaker 1: you know. And again a global shutter would not have
Speaker 1: that problem because it's taking all that image, you know,
Speaker 1: it's taking all the information all at once. The rolling
Speaker 1: shutter is taking it bit by you know, line by line.
Speaker 1: And again it's only if you're panning very quickly, because
Speaker 1: it's this is going so many times per second that
Speaker 1: if you're doing a nice slowe hand, it's it's not noticeable. Also,
Speaker 1: you're more likely to prevent the kind of nausea that's
Speaker 1: associated with the quick panning of Yeah, we'll get to
Speaker 1: the human advantage to that too. Next is the wobble. Yes,
Speaker 1: so you don't have this problem. No. This is wobble
Speaker 1: is when you get sort of a weird, stretchy or
Speaker 1: rubbery look to stuff that's going on in the video.
Speaker 1: And it tends to happen with handheld footage, right because
Speaker 1: you're when you're holding the camera, you don't have that
Speaker 1: steady base that you would if you're using a tripod.
Speaker 1: So let's say like a found footage film sure becoming
Speaker 1: more and more popular these days, So something like all
Speaker 1: onlines of Blair Witch or clover Field or or one
Speaker 1: of those movies or or or vhs made by friends
Speaker 1: of mine. Check it out. It's us. It just premiered
Speaker 1: over at Sundance. Um, that's a shout out to my
Speaker 1: buddies anyway, So same sort of thing. It's it's because
Speaker 1: of that rolling shutter. The information is being captured line
Speaker 1: by line. If your camera is not steady then and
Speaker 1: if it's moving around quite a bit and at a
Speaker 1: fairly fast pace, then it's the The images are not
Speaker 1: going to be uh, they're not gonna be clear. They're
Speaker 1: gonna end up having this wobbly, stretchy look. So let's
Speaker 1: say you're panning uh down, so you've got you you
Speaker 1: maybe you've got your looking at the top of that
Speaker 1: tower and you start panning down very very quickly to say,
Speaker 1: simulate a fall. So uh, we're panting down very very quickly.
Speaker 1: That rolling shutter is going up from the top to
Speaker 1: the bottom very quickly. As you are going down, the
Speaker 1: shutter is going to uh. If you're matching the shutter
Speaker 1: speed or getting close to the shutter speed, it's going
Speaker 1: to make that building stretch out, it's gonna look very odd. Um.
Speaker 1: And so that's another one of those issues. And again
Speaker 1: the global shutter doesn't have that problem because it's not
Speaker 1: it's not capturing information the same way. Uh. And then
Speaker 1: finally there's partial exposure. Partial exposure happens when light is
Speaker 1: hitting the shutter or the the image sensor at a
Speaker 1: very particular moment and and the light is hitting it
Speaker 1: just fast enough so that when the rolling shutter starts,
Speaker 1: the light's not there. But before the rolling shutter has finished,
Speaker 1: it's it's a journey across the image sensor. The light
Speaker 1: has coming gone, which means that part of your image
Speaker 1: is going to be much brighter than the rest of
Speaker 1: your image. So if you think about your image as
Speaker 1: h let's say you're taking a picture of, say a poster,
Speaker 1: all right, you gotta you're looking at a poster and
Speaker 1: there's a flash that goes off as you are taking
Speaker 1: your image, and the flash is moving at a speed
Speaker 1: is a very quick, flat moving it's moving on speed
Speaker 1: that's faster than the rolling shutter is when you actually
Speaker 1: look at that picture, when you're looking at the poster
Speaker 1: in the back, it's gonna look like there's this one
Speaker 1: band of the poster that's much more brightly lit than
Speaker 1: the rest of the poster, and that's going to be
Speaker 1: the moment when that flash hit the image sensor as
Speaker 1: the rolling shutter was going down the sensor. So this
Speaker 1: is another issue you have to work with your lighting
Speaker 1: in order to avoid it. And uh you know it
Speaker 1: can if you're using a flash that's a longer based flash,
Speaker 1: you don't have to worry as much. This is why
Speaker 1: partially why anyway part of it because it's most of
Speaker 1: the the smartphone flashes or l e D s, But
Speaker 1: it's also part of why if you ever take a
Speaker 1: photo with a smartphone that uses an LED flash. It
Speaker 1: tends to last a while. It's because if it didn't,
Speaker 1: then your all your images would come out with this
Speaker 1: weird banding issue. And you don't want bands in your
Speaker 1: in your pictures unless you're at a concert. I'll be
Speaker 1: taking some tonight. Awesome, I'm gonna go see. Day might
Speaker 1: be giants and that's a shoutout. Today might be giants.
Speaker 1: Everyone's getting shout outs today. It's free plug day on
Speaker 1: tech stuff. Well, you know a lot of stuff on
Speaker 1: tech stuff requires a plug. Yes, it's true. Not everything
Speaker 1: is better reoperated. So, yeah, the c c D is
Speaker 1: only prone to the smear issue, whereas CMOS has those
Speaker 1: other three. If you have a decent camera, you shouldn't
Speaker 1: have you know, in our are taking precautions. You just
Speaker 1: have to worry about it, exactly. Yeah, if you if
Speaker 1: you know what you're doing, you can get around these problems.
Speaker 1: It's just that these are the ones that are the
Speaker 1: cameras are prone to based upon the technology they use.
Speaker 1: So it's not that every single image you're gonna take,
Speaker 1: or even even like a significant percentage of the images
Speaker 1: you'll take, will have problems associated with these issues that
Speaker 1: I've talked about, but some of them might and the
Speaker 1: reason why they they have those is because of the
Speaker 1: technology itself. And again, you know, you just little basic
Speaker 1: tricks that you can do, you know, just for example,
Speaker 1: using a tripod whenever you can helps a lot, it'll
Speaker 1: it'll really remove a lot of this. Also, you know,
Speaker 1: most of most people aren't running around and jerking the
Speaker 1: camera left and right so fast that these are really
Speaker 1: coming into play. Uh And if you're using Instagram, really
Speaker 1: you've made your image look so crappy already you don't
Speaker 1: need to worry about these effects. That's that's just a
Speaker 1: joke mostly. Alright, My wife uses Instagram a lot. What
Speaker 1: a lovely old tiny photo of the Space Shuttle. I'm
Speaker 1: so glad anyway, Uh so, yeah, I mean, so, which
Speaker 1: which is better? Really kind of it really does depend
Speaker 1: on what kind of photography you're going to be doing. Um,
Speaker 1: you know, probably the biggest difference is whether you're doing
Speaker 1: still photography or or video. And most of the time
Speaker 1: when you're shopping for cameras, the type of sensor that's
Speaker 1: and it is not necessarily the easiest information for you
Speaker 1: to find out, although it does pay to to look
Speaker 1: into that if you can and and actually do some
Speaker 1: research on the sensor itself, because, like we said, the
Speaker 1: sensor and the lens of the camera is going to
Speaker 1: have a lot more to do with the quality of
Speaker 1: the images that you get using that camera than how
Speaker 1: many megapixels it has. So even if you go out
Speaker 1: there and you buy a twelve megapixel camera and your
Speaker 1: buddy has an eight megapixel camera, your buddy's images maybe
Speaker 1: may look sharper and more vibrant than yours. Again, not
Speaker 1: to do with the megapixels. It's more about the lens
Speaker 1: and the sensory And of course, if you're you're planning
Speaker 1: on dropping a lot of coin on a new camera,
Speaker 1: probably would be a good idea if you read some
Speaker 1: reviews from professionals to give you an idea of what
Speaker 1: you expect to see. If if other people are using
Speaker 1: it the same way, you will be um to get
Speaker 1: to really get an idea of how you know whether
Speaker 1: it's going to suit your needs, and that's the most
Speaker 1: important thing. Very good, Yes, good advice from Mr Bled
Speaker 1: And that wraps up another classic episode. Hope you guys
Speaker 1: enjoyed it. If you have any suggestions for future episodes
Speaker 1: of tech Stuff, why not, right in The email address
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