The Wild Photographer

All About Camera Sensors: Understand them and Improve your Photography

• Episode 84

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In this episode of The Wild Photographer, Court takes a deep dive into one of the most important but often misunderstood parts of your camera: the digital sensor.

While camera sensors can sound technical at first, understanding how they work has a very real impact on the photos you make in the field. From ISO and noise to dynamic range, RAW files, megapixels, sensor size, rolling shutter, and even sensor dust, this episode breaks down the core concepts with practical advice in a photographer-friendly way.

Court explains the sensor as a light-gathering tool—the digital equivalent of film—and uses the helpful analogy of tiny “light buckets” to explain exposure, blown highlights, low-light performance, and why getting more real light to your sensor is often the key to better image quality.

Whether you’re photographing a jaguar at dusk, a polar bear on snow, birds in flight, or a sunrise landscape, understanding your sensor helps you make better decisions in the field. This episode is all about turning the technical side of photography into practical knowledge you can actually use.

Expect to Learn:

  • What a digital camera sensor actually does
  • The difference between photosites and pixels
  • Why high ISO creates noise—and why ISO is not the enemy
  • How sensor size affects low-light performance and dynamic range
  • When more megapixels help, and when they can create trade-offs
  • Why protecting highlights matters so much in digital photography
  • How RAW files preserve more of what your sensor captures
  • How cameras interpret color
  • Why a properly exposed high ISO image can beat an underexposed low ISO image
  • What ISO invariance and dual gain sensors mean in practical terms
  • When to use mechanical vs. electronic shutter
  • How rolling shutter can affect wildlife and action photography
  • What BSI and stacked sensors mean for modern camera performance
  • Why phone cameras are impressive—but still different from larger-sensor cameras
  • How to prevent and manage sensor dust in the field

Key Takeaways:

Your camera sensor is not just a spec on a camera brochure. It is the heart of your digital camera and the thing that determines how your camera receives light. Once you understand how your sensor works, you can expose more intentionally, choose ISO more confidently, protect important highlights, shoot RAW when quality matters, and make better creative decisions in the field.

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Court (00:00)
Hey friends, welcome back to the Wild Photographer Podcast. I'm your host, Court Whelan and today we're talking about one of those topics that sounds pretty technical at first, But I promise you it has a very real impact on your photos you make in the field because you're gonna understand your camera a lot better. Today we're talking about how sensors work in digital cameras.

And I know right off the bat that might seem like we're headed into a robust physics lecture,

But stick with me here, because understanding your sensor, even at the very basic level, helps explain so many things that photographers bump into every single time they go out with a camera. It explains why high ISO creates noise. It explains why bigger sensors

generally perform better in low light. It explains why RAW files are so powerful. It explains why highlights can get blown out and never come back, never be rescued in Photoshop Lightroom Camera RAW.

It explains why some cameras are better for wildlife action, some are better for landscapes, some are better for video, and why your phone can do pretty miraculous things, but still isn't quite the same thing as a big fancy camera with a big old fancy lens and a big sensor.

And maybe most importantly, the information in this episode will help you make better decisions in the field.

Because that's the goal of this episode. This is not engineering for engineering's sake. This is not how to win a trivia night with your camera store. Although honestly, if there is a camera store trivia night somewhere, I'm totally in. That sounds delightful and really exciting. The goal today is to help you understand what is happening inside your camera at the moment you press the shutter button. So that when you're photographing, let's say, a jaguar at dusk or a polar bear on snow or a landscape at sunrise, you have a better sense of what your camera can do, what it cannot.

And where you as the photographer really need to step in and make conscious, intentional decisions.

Before we get into the show, I want to thank ArtHelper.com. ArtHelper's mission is to create a brighter future for human artists in the world of pretty much infinite AI content. We see the direction this is all going. ArtHelper is no longer just a powerful tool set designed to assist artists in the distribution and promo of their work. It's now a professional networking community for creators of human-made art. It's a really energizing real-time feed of artwork, discussions, critique, and art world news.

It's also a global human artist directory that art buyers can trust with curated galleries of real, again, human-made art. Most importantly, it's absolutely free to join, so go to www.arthelper.com and check out their amazing art communities as well as their robust set of tools for photographers. All right. Well thanks ArtHelper and let's get into the show.

Okay, first things first, what actually is a digital camera sensor? Well, at the simplest level, the sensor is the digital equivalent of film. Back in film days, light came through the lens and landed on a strip of chemically treated film. That light caused a chemical reaction, and that reaction eventually became the photo. In the world of digital cameras, it's similar but different. Light comes through the lens and lands on the sensor. And instead of causing a chemical reaction, that light is just converted into electrical signal. That's really the heart of it.

Light comes in, the sensor measures it, the camera turned that measurement into an image. Now, of course, there's a lot more going on because of course there always is, and especially with these little computers that are in cameras these days. doing pretty ridiculous things in a fraction of a second.

But at its core, the sensor is just a light measuring device. I want to underline that point. It is a light measuring device. So when you hear me or anyone talk about how photography is really all about the light, well, there you go. Your sensor is the thing capturing it and it's capturing light. You could be in a beautiful scene overlooking the Grand Canyon, but if it's pitch black without any stars, without any moonlight, with nada, you don't get anything. So you are capturing how light plays.

is emitted, is reflected, and ultimately perceived by the sensor. And I actually think that's a really helpful way to think about photography in general. Your camera is not seeing the world the way you see it. It is measuring light. So you yourself to become a better photographer have to get more versed in seeing and recognizing beautiful light. So your camera can ultimately measure it.

It doesn't know that you're looking at a gorgeous lion It doesn't know that you've waited three days for this one moment and it's doing some incredible behavior.

It doesn't know that the sky is really, really pretty, or the background is distracting, or that the catch light in the animal's eye is perfect. It it doesn't look at things that way. It's just measuring light. So it just knows how much light is hitting each tiny little photocyte on the sensor.

and I'm using that word very intentionally, photocyte. That's photo-s-I-T-E.

Cause this is where we need to separate two terms that often get pretty blended together, pixels and photosytes. A photosight is the little light catching area on the sensor itself. It's like the physical bucket

that basically gathers that light. A pixel is what you eventually see in the final image. So similar but distinct differences.

Those terms can be often used interchangeably and in everyday camera talk, that's a-okay. Like sometimes we just need to get the point across. We say a 45 megapixel sensor, and we mean that the camera produces an image with about 45 million pixels. But technically, the sensor is made up of millions of these little light-gathering wells, and each one is measuring light. So here's the metaphor I want you to keep in your head for the rest of the episode. Imagine your sensor is a giant grid of tiny rain buckets. I know. Stay with me here.

Each bucket is that photosight. And instead of collecting rain, each bucket is collecting light. Light is the water. Light is the thing filling up these buckets, these photosytes. When you press that shutter button, the camera opens the exposure and light starts falling into those buckets. The bright part of the scene fills a bucket very quickly, the dark part of the scene fills a bucket slowly. And when the exposure is done and over, the camera looks at all those buckets and says, okay, this bucket got a lot of light, this bucket got very little.

This bucket got somewhere in between, you know, we're thinking you know, a little Goldilocks scenario here going on just just the right amount of light and so on and so on. The map of light levels becomes the foundation of your photo.

Now, this little rain bucket analogy explains quite a bit of photography. Let's let's start with exposure. When we talk about exposure, we're talking about how much light reaches the sensor. Aperture controls how wide that opening is. oftentimes I'll make a similar analogy with like a water spigot. You know, if you have a big opening like a fire hose, it's gonna let in a lot of light really quickly. Aperture is that that diameter, it's how big the opening to your sensor is through the lens. In fact, if you

Look at a lens, you can start to see how this little iris ring opens and closes as you go from say F4 to F22. The bigger the number, the smaller that aperture opening, and vice versa. Then you have shutter speed. This is the second part of what we often refer to as the golden triangle. So aperture number one, shutter speed controls how long that opening is available.

Then ISO controls how the camera handles the signal after the light has been collected. And this is where things get really, really interesting because ISO is probably the most misunderstood part of this golden triangle or exposure triangle. ISO does not make your sensor more sensitive to light in the way we often kind of casually say it does. The phrase is useful and it gets the point across, and I I do say it too, because it's a very quick, easy way to explain it. But technically, when you increase your ISO,

You're mostly amplifying the signal that the sensor captured. So if your sensor collected a small amount of light because you're photographing in, let's say, dim conditions, sunrise, sunset, dawn, dusk, raising the ISO brightens that signal, but it also brightens the imperfections in that signal. And that's when we kind of get into this idea of noise. Think of it like audio. If you record someone speaking very quietly in a room and then you crank the volume way up.

Yes, the voice gets louder, but so does everything else. The the hiss, the air conditioning, the fan, the hum, all that background noise, that weird little electronic buzz you may not even perceive with your own ears and didn't even notice at first at that lower volume level, that gets exacerbated. So it's the same thing with optics and with the sensor. If the signal is strong, meaning you collected lots of real, honest to goodness light, the image looks clean.

If a signal is weak and you amplify it digitally via ISO quite a bit, the image starts to look noisy or grainy. We kind of use those two terms very interchangeably. It does look like grain is on top of the photo. That's it's a noisy photo as we call it in in the biz. This is why low ISO generally gives you the cleanest files. Not because ISO 100 is is magical for any reason, but because ISO 100 usually means you had enough light to begin with.

And the sensor get a really nice, strong, clear signal. Think of it like being in a padded room with a really pro-level microphone to keep that analogy going. and this is one of the biggest takeaways, a very practical one of the whole episode. If you want cleaner files, collect more actual light wherever you go.

that might mean using a wider aperture, like an F2.8 instead of a 5.6. Remember that quadruples the amount of light if you look at the aperture charts.

it might mean using a slower shutter speed if the subject allows for it. It might mean using a tripod for landscapes. It might be just truly waiting for better light. it might mean moving your subject if you have control over that, like especially with people photography, into better light. But the key is this, ISO is is not your enemy. I think it as a this a magical unicorn silver bullet kind of thing. I use high ISO all the time, and I will shoot at ISO of 3200, 6400,

twelve thousand eight hundred and sometimes even higher if the scene absolutely requires it. But the reason high ISO can look rough is because the sensor simply didn't receive that much light in the first place. So the fix is not always ramp up your ISO or get a better camera that can handle high ISOs better. Sometimes the fix is just truly

Figuring out how you the photographer can get more light into the sensor.

Okay, so let's talk now about probably a question that might be percolating in your mind: sensor size. You heard me talk about a camera that can handle ISO better. You've heard terms like full frame, crop frame, APS C, micro four-thirds, medium format, which is a big old one, a one-inch sensor, and of course you have your your phone sensors.

So what does sensor size actually do as it pertains to the quality of your image? Well, simply put, a bigger sensor gives you more physical area to collect light. That's a good thing. Remember that rain bucket analogy. If you have a bigger backyard with more buckets, you can put out bigger buckets or more buckets or maybe even both. And if the buckets are bigger, they can collect more light before they fill up.

So that helps with a few things. First, bigger sensors generally have plain and simple, better low light performance. That's why I personally stick with a full frame sensor because I'm often in challenging lighting conditions. If you're a studio photographer and you have flashes and lights, not as big of an issue. Although I think pro-level studio photographers probably also go for full frame sensors for other reasons. But ultimately, bigger sensors do have better low light performance. And that's probably their single best, biggest advantage.

But second, bigger sensors generally have a better dynamic range as well. third, bigger sensors also give you more flexibility in editing.

fourth, bigger sensors usually make it easier to get a shallower depth of field, especially when paired with the right lenses. Now, there are asterisks all over this. Camera technology is changing fast. There are crop frame cameras that are phenomenal. Don't think that a micro four-thirds is making for a

demonstrably worse photo. Like I've I've shot with OM systems that are micro four thirds and they're phenomenal. There's a lot of camera tech that goes into the behind the scenes, how it processes all that. But you can have amazing wildlife and nature photography with any of these things. and there are also phones doing computational magic that would have seemed kind of like wizardry not too long ago. But at the end of the day,

physics is still physics. A larger sensor has more surface area to collect light.

And collecting light is the whole game here. This is why full frame cameras tend to do better at these high ISOs versus smaller sensor cameras. It's not that the smaller sensors are bad, it's just that the sensor is working with less real estate.

Remember fewer buckets. Now, does that mean everybody needs a full frame camera to be a decent photographer? No, absolutely not. And I want to be very, very clear about that because it's really easy for gear conversations to kind of drift into bigger and more equals better, and you must upgrade immediately or indefinitely. And that's not where I'm going with this. Smaller sensors also have advantages. Let's talk about those. They're they're lighter, they're less expensive, the lenses are smaller.

And they give you more reach for wildlife because of that crop factor. Remember, if you have a crop frame sensor, you may not know it, but they all have some sort of multiplier such that if you have a 200 millimeter lens on, let's say, a Nikon crop frame sensor, you get a 1.4 times on that 200 millimeter, which means you get a 280 millimeter lens. Same thing with a 1.6 crop factor for Canon, et cetera, et cetera. so yeah, if you're traveling, if you're hiking.

If you're going out on things like kayaks or into rainforests in the Arctic, if you're anywhere where size and weight matters, a smaller system might be truly the right choice. But if you're often shooting in very low light, pushing the high ISO, finding that you're getting noisy and grainy photos no matter what you do, if you are also planning to edit heavily, if you're printing big or trying to get just a super clean pro-level photo, then yes, sensor size definitely matters.

It's not everything, but it does matter.

Now let's go on a a little bit of a level deeper here and talk about megapixels. Megapixels do get marketed like crazy. They're they're always one of the

first numbers people see when they're shopping for cameras, like on the camera promo, in the email, on the website. You know, you've got all sorts of different ones. I'm not gonna list every variation, but they could be 24, 33, 45 megapixels. And there are even cameras out there nowadays that are not your $20,000 version, but kind of like

pro Sumer levels like within reach for many of us at 61 megapixels. So it seems kind of like more is better. but that's that's a big assumption. Sometimes it's yes, sometimes it's no.

megapixels are basically the resolution of your image. More megapixels means more detail. It also means more ability to crop. That's a huge benefit. And also the ability to print larger. For wildlife photography this can be a really really big thing especially if you're shooting on smaller lenses.

More budget telephotos or even the big primes. If you're photographing a bird and you can't physically get closer to it, or you shouldn't get physically closer to it, because of ethics, or maybe it's safety with polar bears or grizzly bears, having more megapixels gives you cropping flexibility later. And I absolutely love that. It's something that I use religiously. for landscapes, more megapixels are great as well. It can give you extraordinary detail and you can print off really, really big, like

I printed off a landscape photo recently that was 48 inches by 72 inches, that's four feet by six feet, and I can get right up to it and it just looks great. But remember, there is always a trade-off with all things in life. if you put more and more megapixels in the same sensor size, each individual photo site may become smaller,

And smaller light buckets collect less light. So we see this this discord, this this metaphorical contrast here. now modern sensors are so good that this is not as dramatic as it used to be. Engineers are doing amazing things with sensor size. it has to do with noise reduction and backside illumination and stacked sensors, something we'll talk about here in a bit, and all sorts of other really cool stuff. But conceptually, this matters. A 61 megapixel full-frame sensor may give you.

Huge cropping power and great detail, but it can also be less forgiving for things like camera shake. it maybe lens softness, exacerbating some imperfections in the lens. missed focus will look even more pronounced and just general technique flaws. A 24 megapixel, on the other hand, full frame sensor, may not crop as much, but it might be excellent in low light and produce smaller files that are much easier to work with. So you might be wondering.

know some of these camera manufacturers come out with their flagship camera you know it's it's like the six seven thousand dollar camera and it comes with a twenty four megapixel sensor and you're wondering why in the heck would they not put sixty one megapixels? The the tech is out there it's possible. Well these are some of the reasons. So the practical takeaway is this you choose megapixels based on how you shoot. If you photograph wildlife and crop a lot more megapixels can be really helpful. I find it to be so if you photograph landscapes and print large

More megapixels can be very helpful. But if you mostly share online photograph travel, you just want smaller files. Remember the bigger files take more memory, more processing speed on a computer. I'll never forget, you know, as I've upgraded cameras over the years, I'll get a camera, you know, every three or four years, a camera body, and I find, my gosh, now I have to get a better computer. So it's it's a real thing when we talk about file size.

But as well, if you value low light performance and speed, you may not need that big megapixel monster. There's real data and real science that says it might not be as good as those smaller megapixel sensors. And I say that as someone who absolutely understands the allure of megapixels. Like cropping is wonderful. Cropping is like having a bit of a forgiveness in your back pocket. It's it's not free. It comes with file size, storage, processing, and really perfecting techniques,

But it's a big decision to make when you're thinking and shopping for a camera because a lot of what you're buying is the sensor.

Now let's talk about dynamic range Because this is one of the most important sensor concepts for actually taking better photos. Dynamic range is essentially the sensor's ability to capture detail in both very bright areas and very dark areas in the same photo. and I will say that our eyes, this goes back to what I was saying before that

The camera doesn't see the way our eyes see. Our eyes are extremely good at dynamic range. Like we see lights in the shadows, and we can adjust our eyes and our pupils to manage excessively bright conditions. Like I don't need to tell you, you walk outside on a bright day and you you feel that happening. but cameras work a little bit differently. So think of a sunrise landscape. You've got a a super bright sky and a relatively dark foreground, or maybe it's a polar bear on snow with shadows in the fur or increases in the snow.

Might be a gorilla in a dark forest with little beams of sunlight blasting through the canopy. Dynamic range is the camera's ability to hold detail across the entire range of tones. Okay, so it it's more data, it's better data. a sensor with high dynamic range can preserve more highlight detail and more shadow detail at the same time. Okay, so high dynamic range is a good thing.

A sensor with lower dynamic range might force you to make a choice. You either expose to the sky and lose that foreground, or you expose to the foreground and blow out the sky. The sky is just too bright. And so here's the really important part. When a highlight is truly blown out, like if you look at the histogram and your little graph is all the way to one side, it's completely gone. You will never be able to get color, texture, anything up there. You know, the the highlights might be the top of the mountain. It's not gonna be there in your photo with

all the magical photoshopping you can possibly do.

If those light buckets overflow, there's no information left to recover, simply put. The camera just knows and really just thinks this is pure white. It doesn't know if pure white was a cloud or polar bear face, a waterfall. It's just white.

So that's why you'll often hear photographers say protect your highlights, like expose for the highlights. That means when you are in front of that landscape scene, you meter or you expose for the really bright stuff, knowing you can oftentimes rescue the light in shadows. You can boost the light there. You really can't rescue highlights. So it's really good advice. It's a good takeaway, but this isn't always, always the case. There are times to intentionally blow highlights for a very high-key look. You've heard me talk about this before. I I love the

the high key look where things are very bright. This is great for magazine photography. it's even really great for social media photography. People have

often said and there are legit studies on this that, you know, overly bright photos do really well on Facebook and Instagram and probably TikTok too. Like it just it captures the attention a little bit faster. So it's not like a a hard and fast rule, but if you do care about the detail in a very bright area, you need to protect it in your camera.

So again, this is where your histogram and even highlight alert features, sometimes called blinkies, just colloquially, they become so, so useful. The LCD screen, it can lie to you. It can be wrong. You know, the LCD screen is backlit, it's adjusting for bright conditions or dark conditions. Never take what is in the LCD screen as the gospel because it can misrepresent what those bright and dark spots really look like depending on how you're looking at your LCD screen. Again, bright sun, dark shade, at night, all these situations.

But the histogram, if you wish to embark on this slightly complex mission, it gives you a way better sense of what the sensor actually captured. the chart on a histogram is like data. If everything is smashed against the right side, you may be blowing out your highlights. If everything, meaning like the graph is smashed against the left side, you may be really overly darkening your shadows.

And again, this is not about chasing a perfect histogram all the time. there really is no perfect histogram. Like this is art. It's your interpretation of things. a photo of a polar bear in snow when we're talking about the histogram should look very, very different versus a photo of a dark gorilla in dense, dimly lit rainforest. It's gonna be skewed to one end or the other. We're not always going for the bell curve.

But the histogram does tell you what's happening to the data. And let's be honest, digital photography is about data. So that sounds kind of unartistic and unromantic, but it's very, very true. You are making art with data. Let's just call it what it is.

Now let's talk about RAW files because this is where the sensor conversation becomes very, very practical. When you shoot in raw, you are saving much more of the sensor's original information. I'm gonna say that again. Shooting in RAW saves much more of the sensor's original information. When you shoot in JPEG, the camera processes the image for you and it just throws away a lot of information to create a smaller, more compressed, finished, frankly,

better out of the camera file. It's gonna look better, but the RAW has the data. So this doesn't mean that JPEG is bad. JPEGs are convenient. I will sometimes shoot on RAW plus JPEG. So I have something really quick and processed and smaller that I can email or text or post on social. They do look good right out of the camera. Like I said, they're easy to share.

and so for casual shooting, they're totally fine.

But if you want maximum flexibility, especially in nature photography, wildlife, landscapes, things with like difficult situations, especially high contrast scenes or dimly lit scenes, raw is the way to go. Raw gives you more room to adjust exposure, recover highlights, you can lift shadows, like brighten them, you can change your white balance, refine color, and process the image really in your own artistic style.

And this connects directly to the sensor. The sensor captured a bunch of information. Ra keeps much more of that information available. JPEG says, Cool, we made some decisions for you. Hope you like them. Ra says, here's the good stuff. You figure it out and tell me what you want me to do with it. And for me, that's really incredibly valuable, especially with white balance. This is something I talk about a lot. I like choosing white balance in the field because it affects how I see the scene and how I think creatively.

But if you shoot in raw, you actually have enormous flexibility to adjust white balance later, Like near perfect flexibility. That's because the sensor itself is not really seeing a warm or a cool scene the way we think about it. It's measuring light through color filters, and the camera or software later interprets that into the colors we see.

Which brings us to one of the coolest parts of the sensor. A little bit nerdy, but this is color. So how does a camera sensor see color? Well, before I get into that,

I want to take a quick break and thank one of the sponsors of the show, MPB. Maybe your style's evolving, maybe a lens just isn't pulling its weight anymore, Or maybe you've got your eye on something fancy and new. Whatever it is, that upgrade cycle is a real thing, and this is where MPB comes in. MPB is hands down one of the easiest ways I've found to buy, sell, or trade camera gear.

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You get a super fast quote, you ship it off with free insured shipping, and once they check it out, you get paid directly. No back and forth, no awkward meetups, no guesswork. So whether you're upgrading your kit, simplifying what you bring with you on a day-to-day or on a trip-to-trip basis, or maybe just needing some cash for an upcoming adventure, MPB is absolutely worth checking out. Buy, sell, or trade with MPB and keep doing what you love. All right, let's get back into it.

so yes, how does a camera see color? So this is pretty wild, but most digital cameras do not have full color pixels in the way you might imagine. Instead, each photo site is filtered to measure primarily red, green, or blue light. Okay, red, green, or blue. The most common arrangement is called a Bayer filter pattern.

It's usually a grid of red, green, green, and blue. Notice there are two greens there. That's because human vision is especially sensitive to green, and green plays a big role in perceived brightness and detail. It's also the reason why if you are photographing landscape or nature and you oversaturate something, the greens are the first to be like obviously messed up. So the sensor captures a mosaic of red, green, and blue information.

Then your camera raw processing software basically estimates full color information for each pixel based on the surrounding pixels. I know this is getting nerdy, this is getting deep, but it's important. And somehow

out of all that, we get a beautiful, accurate color photograph, which is pretty bonkers. I mean, truly, it's it's kind of a wild thing when you think about it. You point a camera at, let's say, a toucan in Costa Rica, photons bounce off this tropical bird, pass through a lens, go through an aperture, hit a sensor through microscopic color filters, become electrical signals, get converted into numbers, interpreted by software,

and suddenly you're looking at a beautiful image of a bird you just saw with pretty darn accurate colors. That is amazing. But it also explains a few practical things. First, color is interpreted, it is not just captured in a pure sense. your camera profile, white balance, picture style, and raw processor all affect the final color.

Second, different cameras can render color differently, even if the exposure is similar. You've probably heard people say, I love Sony for the colors, or I love Canon for the colors. Leica's colors are just so great. That's that's a real thing.

shooting in raw gives you much more control over that color interpretation after the photo is taken.

But remember, raw gives you that flexibility, but it's it's not infinite. You know, I mentioned the green thing, oranges have the same thing. So remember, you you can't fully rescue absolutely everything, but it does give you a pretty big leg up.

Okay, now let's go back to that topic of noise or grain. Noise is one of those things that photographers like myself kind of obsess over, and and I, you know, I totally get it.

Nobody wants a great shot of a great sighting ruined by this sandpaper-like texture over the photo. But noise is also a bit misunderstood. At a very basic level, noise is just a random variation in the signal. It's the sensor and electronics saying, Well, we're pretty sure this is the right level, but there's some uncertainty here. So it's kind of

let's say maybe a bit of a a guesswork error situation. and there are different types of noise, but for practical purposes we can think of it in a few different buckets here as well. There's photon noise, which comes from the random nature of light itself. There's read noise, which comes from the electronics reading the signal off the sensor. Then there's thermal noise, which can increase with heat and long exposures.

then there's the noise we notice when we brighten dark images or use high ISO. The important field lesson and takeaway in all this is that noise is most visible when the signal is weak. This is why shadows get noisy first. that's why underexposed photos get noisy when you brighten them later. that's why a high ISO image can look surprisingly clean if it was well exposed, while a low ISO image can actually look pretty rough if it was severely underexposed.

And simply rescued and brightened in editing. So this is a huge, huge point. ISO number alone does not determine image quality. Exposure quality matters a lot. A properly exposed ISO 6400 photo, which is a pretty high ISO by most standards, can actually look better. Remember, when it's properly exposed, this can look better than an underexposed ISO 800 photo of that same thing that you then had to brighten by two or three stops in Lightroom.

So when I'm in the field, I'm not just thinking how do I keep ISO low at all costs? I'm thinking how do I get enough light to the sensor for the photo that I need, or pretty darn close. Sometimes that means accepting high ISO because I need the shutter speed, but if I'm photographing a moving animal at dusk, I would rather have a sharp, properly exposed, high ISO photo than a blurry low ISO photo. Noise can be improved. Blur is usually forever. Like you're kind of stuck with that. You yes, there are Topaz sharpening programs, but

Once something's blurred, you've kinda lost a shot.

This is another big takeaway I want to give you, is that noise can be improved, but blur cannot. Now, of course, denoise software is getting extremely good. Lightroom, Camera Raw, Topaz, all these tools can rescue files in ways that honestly feel like a bit of a a mild miracle, but don't let denoise become an excuse for sloppy exposure, truly,

get the best file you can in camera, then use the software to polish it. You know, you're not going into Lightroom, Camera Raw with a wrecking ball. You're going into it with a small little rock chisel. And in that order truly matters. Always prioritize getting the exposure right in camera

And then use software to fine tune it.

Okay, so I want to go a little bit deeper here and talk about ISO invariance and dual gain sensors. And I promise I'm not gonna go too deep in the weeds here because it can get pretty complicated very quickly. But this is one of those advanced topics that can really help you understand your camera better, which translates to getting more and better photos.

So modern sensors are known to be quote unquote close to ISO invariant over certain ranges. What that means is that in some cases, brightening the image later in raw processing can produce a similar result to actually raising your ISO in camera. So the basic gist here is that with some cameras, shooting at ISO, let's say 800 and brightening later may look very similar to shooting at ISO 3200 in camera, at least within certain limits.

Now I'm not recommending that everybody go out and intentionally underexpose everything. Please do not do that and then blame me when you you can't rescue your files properly.

The the practical lesson here is is quite a bit more subtle. It means that your camera's sensor and processing pipeline, let's call it, have certain ISO ranges where performance changes.

so the basic gist is that ISO isn't quite linear in the sense that the higher ISO is always going to be worse.

There are actually ISO ranges where performance changes. Some cameras have what's called dual gain architecture in them, where the sensor effectively switches to a cleaner readout mode at a certain ISO.

You may have heard people say things like, My camera actually gets cleaner at ISO 800 versus a lower ISO.

Or you might hear them say, There is a second native ISO. That's this is what we're talking about here. For most photographers, the key takeaway is that it is probably worth learning your specific camera and what those ISO ranges are. And I'll tell you, there are so many makes and models out there, and they're all a little bit different.

But you can quickly go on YouTube, you can go on Google, and you can figure this out. You don't have to be obsessive about it. You don't need to spend a month photographing gray cards in various lighting conditions unless you truly want to. but it's worth knowing where your camera performs best. How high can you push ISO and still feel good about that file and photo?

what ISO does noise start bothering you? How much can you lift the shadows before the image falls apart?

does your camera have an actual dual gain point? These things are often selling points, but they may be buried because they are pretty technical. So this is especially helpful if you photograph wildlife at dawn or dusk. Similarly with night skies, things like Aurora could be indoor scenes like great travel photos in lodges and camps, or really anything where you're constantly thinking about low light.

I will tell you, I've done these tests over the years. Fortunately, it's been mostly field-based. Just getting back from so many expeditions, I can see, yeah, when I'm in a dimly lit rainforest, as soon as I go over ISO 3200, I start to notice it. As soon as I go over 6400, other people start to notice it. Or if I go to 12,800 but I get the exposure right, I can denoise it and it can be a really, really great photo. so doing some experimentation.

Doing some work, doing some research really is a huge, huge thing.

So let's talk about shutter types, because this is where sensors really get important for wildlife and action photography. Most digital cameras today give you some version of a mechanical shutter and an electronic shutter. A mechanical shutter physically opens and closes to expose the sensor,

Whereas an electronic shutter actually turns your sensor's exposure on and off electronically. Electronic shutters can be absolutely amazing. They are silent, they allow for super fast frame rates. Like that's how we're able to get these 30 frames, 60 frames, even 120 frames a second that we see out there. can also reduce mechanical wear. You don't have moving parts. Oftentimes camera bodies are sort of rated

Just like how a car's mileage or a boat's motor time might be an indication of of life left in it.

People that really know what they're looking for when they're buying used cameras will ask what the shutter count is. And that mechanical shutter will basically give you an odometer of how many times it's moved. And yeah, these things, they do fail. Now, not anytime soon. Like you can have a camera easily, 10 years. We're talking about hundreds and hundreds of thousands of shutter clicks before these things start to go. But nevertheless, electronic is great because you don't have those moving parts

So I truly love electronic shutters. I shoot on them most of the time. I love the silent nature of them. I love that I'm not click, click, click when we're seeing a rare special wildlife sighting. Maybe someone around me is taking video and I don't want to be that guy that has the loud shutter. It can be great for quiet cultural ceremonies or really just anywhere and any time where shuttered noise is disruptive, which I I think it can be in almost every scenario. But there is a catch.

So most CMOS sensors, that's what we have a lot today in digital cameras, they actually read the image line by line from top to bottom. So remember the sensor's capturing light, it's capturing the data, but it's not doing one big catch-all all at the same time. It has to go in sequential order and usually from top to bottom. This happens very, very quickly, but it's not perfectly instant. So if your subject is moving fast or if you pan really quickly, this is very, very common with like bird wings or

helicopter rotors. the top of the frame and the bottom of the frame are not captured at exactly the same moment. And this can cause distortion. Vertical lines like the straight lines of a helicopter blade can be a little bit warpy.

Vertical lines can lean, fast moving wings can look pretty distorted and warped.

And this is rolling shutter. Mechanical shutters reduce this in many situations because of how they expose the frame, although they do have their own limitations. So global shutters solve this by capturing the entire frame all at once. This is hugely valuable for fast action because it avoids that rolling shutter distortion. And we see this in some of the flagship cameras from the major manufacturers. Nikon just came out with one, Sony just came out with one. Pretty sure Canon has one or they will be coming out with one.

But global shutter technology has historically come with their own trade-offs, often in dynamic range or low light performance, although that is improving markedly.

So, what do you do with this information? Well, here's the practical advice: if you're photographing relatively still wildlife or landscapes or just general nature, electronic shutter can be absolutely great. If you're photographing super fast action, birds in flight, running animals, you are panning your camera really fast, things like wing beats or anywhere in anything where distortion really matters. Like, I don't know if anybody out there is gonna be doing

Helicopter or prop plane photo shoots, but this this is what we're talking about. test your camera. See how electronic shutter performs in those scenarios. A great way to do so at home and indoors is a ceiling fan. if you notice a weird warping from your ceiling fan, you might want to switch to a mechanical shutter

Or electronic first curtain if your camera offers it.

And if you're using a silent shutter for wildlife, which I do use a lot, just remember that silence is not always automatically better in all cases. It it might be ethically better, morally, you might just enjoy your time more. It might be the right thing to do. And I think in many cases it is, but it can give you that rolling shutter. In addition, a lot of photographers will keep their click on even with electronic shutter, just to know that they're getting the photos. Cause it is kind of weird when you're in front of this amazing wildlife scene and you're firing off.

20, 30, 40, 50 photos and you can't really tell if the photos are taking. Like maybe a little box shows up, maybe the screen goes black for a brief instant, but having that little noise that maybe is so low that only you can hear it can be a helpful thing.

Now let's talk about stacked sensors and backside illuminated sensors because you'll see these terms in a lot of camera marketing and even reviews. A backside illuminated sensor or a BSI sensor for short is designed so that more light can actually reach the photodiodes, the light sensitive parts of the sensor. In older frontside designs, some of the wiring and circuitry could actually get in the way of incoming light.

So BSI moves things around to basically improve light gathering efficiency. The practical benefit is usually better low light performance, better efficiency and cleaner files.

A stacked sensor goes another step by layering the sensor components.

often allowing much faster readout speeds. And that can basically translate to faster burst rates, like more frames per second. It can translate to better autofocus abilities and calculations, maybe better video performance. And once again reducing that rolling shutter.

This is one reason some high-end mirrorless cameras are so dang good for wildlife and sports. They're not just fast because the processor is fast. They're fast because the sensor itself can be read very quickly. And it's kind of weird to differentiate between the two, but it's just important to know that there are so many components going on in the inside of these things, all related to the sensor, that high-end cameras, it's it's not just the megapixel count. There's a lot of stuff going on there.

So when you're comparing cameras out there, especially for wildlife, don't just look at megapixels. Look at the sensor design. Look at the readout speed. Look at rolling shutter performance if that's something that you're concerned about. definitely look at autofocus performance. Look at the buffer depth, like how many photos can you take and transfer your to your memory card per unit time. And just get reviews from folks from pros out there, like how does a whole system work together?

because even though this whole episode is about the camera's sensor and it's a huge part of the camera, it's not only about the sensor. It's not just a sensor with a plastic or metal box around it.

It's a sensor plus the processor, plus the autofocus system, plus the ergonomics and all sorts of other things. It does all matter.

Okay, so let's bring this back around to actual photography decisions. How does understanding sensors help you take better photos? Well, number one is expose with intention. The sensor is collecting light. Give it enough light whenever possible. Don't blindly underexpose everything just to protect highlights, but also don't blow important highlights either. If there's a lot of texture and color and really interesting stuff going on in that bright sky, you might want to expose for the sky.

Also, use your histogram. Use those blinkies as we call them. Sometimes they might be called zebra stripes in your camera. Learn how your camera meters or chooses exposure.

Also protect those important highlights. If the sky is blown out and you care about the sky, that data may be gone forever. And that beautiful photo you thought you had just may not actually materialize. This is the same thing with snow, white feathers, waterfalls, where there's a lot of turbulent water, clouds, even bright soil and sand, reflections. This is especially important for wildlife and bright environments.

All of these can actually trick your metering capabilities in your camera. So this is why I often say when you're photographing, let's go back to the polar bear example, white bears and white snow, if you keep your exposure on dead even at that zero point, you might find that the whole image looks very, very gray. You actually need to overexpose in this scenarios, even though the camera doesn't think you should, you need to because you need to preserve that brightness in the scene that is inherent before you in real life.

in the camera. These challenging all the way to one end of the spectrum lighting schemes mean that you usually need to compensate and tell your camera what to do versus relying on it to make the right decision in the moment.

Another key takeaway is don't fear high ISO. You do need to understand it, but don't fear it. High ISO is not inherently evil. It's a tool, it's it's amazing, it's a silver bullet unicorn situation. If you need a faster shutter speed to freeze movement, use the ISO you need. a sharp, noisy photo beats a clean, blurry photo just about all the time.

But if you can get more actual light to the sensor by opening aperture or slowing your shutter, using a tripod or just simply waiting for better light, do that.

Next up, shoot raw when quality matters. RAW gives you access to more of what the sensor captured, which is unequivocally a good thing. Yes, they are bigger file sizes. You will have to edit them and export them on the computer.

But it's such a powerful tool. If you if you ever want to edit, recover, refine, and make the photo kind of artistically your own, raw is the file format that gives you the most control, simply put.

Another key takeaway, choose your sensor size of your camera based on your real honest-to-goodness needs. Full frame is great, crop sensors are great, micro four-thirds can be great, phones are incredible for what they are, but the right sensor is the one that fits your photographic style, your vision, your artistic interpretation, your travel style, your budget, let's be honest, your weight tolerance, and just frankly your goals.

For maximizing low light capabilities, getting a great dynamic range, and really improving image quality, bigger sensors usually have a clear edge. If you're looking for extra reach or portability or just practicality in the field, smaller systems, i.e. crop frames or micro four thirds, can be absolutely amazing and really shine.

takeaway number six, know your camera's limits, especially with ISO before that once-in-lifetime moment out in the field. You don't want to be learning your high ISO limit after you've gotten back from Brazil photographing Jaguars. You don't wanna figure out that rolling shutter became a problem when you're photographing diving kingfishers in the Amazon.

You don't want to learn about or find your processing or buffer limit after you've taken the photos of the cheetah running on the savannas of Africa. You want to do it ahead of time. So test your camera at home.

Photograph a fan inside with electronic shutter and mechanical shutter and see what the difference might be. It's not totally glamorous work. It may not be super fun compared to photographing wildlife out in the field, but it does and it will pay off.

Now I want to talk about the sensors in phones for just a second because phone photography is becoming, you know, so impressive, and I use mine a lot. and it's sensor-related in a very interesting way. Phone sensors are very tiny compared to most dedicated proper cameras, like teeny tiny.

And tiny sensors you would think would struggle with low light because of everything we've been talking about, maybe struggle with shallow depth of field and even dynamic range. But phones use computational photography to overcome a lot of those limitations. They take multiple exposures and blend them without you even knowing. They reduce noise automatically very, very quickly. They brighten the shadows, they protect the highlights. They can even simulate background blur with things like portraiture mode. They automatically sharpen things

using software. Heck, they recognize faces. They do fancy high dynamic range photography if you tell it to. And honestly, they they are amazing. for travel photography, phones are really, really extraordinary tools. But there is a difference between computationally creating a look and optically capturing it with a larger sensor and lens.

A full frame camera with a 7200 f2.8 is gathering real light through a large piece of high quality glass onto a large expensive sensor. That creates real background compression, real shadow depth, real optical rendering, and really a very, very robust file by comparison to then edit it. A phone might simulate a lot of that, and sometimes it does it very well, but it's not the same tool and it doesn't work the same way.

So I don't think of phones as bad cameras. I just think of them as different cameras for different purposes. They are brilliant for convenience, storytelling, you know, behind the scenes kind of stuff. You can switch to video very easily. But when I want maximum control and taking a photo that I'm probably gonna print out and put in my wall, if I need really great low light capabilities, because I'm really reaching there in the dimly lit rainforests of the Amazon or Borneo, or I'm just

capturing some really epic wildlife stuff with reach, I I definitely still want a dedicated camera with that bigger sensor.

So this is something you may have been thinking about at the start of the episode, and this is sensors and dust. Because if we're talking about sensors, we have to talk about sensor dust and keeping sensors clean. If you've ever seen little dark spots in the sky of your landscape photos, especially at those bigger F numbers like F11 or F16, that might be dust on your sensor. it's not usually dust in the lens because that would actually just be blurred out.

but if you see those pinpointed dots, yeah, you might have to clean your sensor. mirrorless cameras can be vulnerable to this because when you take the lens off, the sensor is often like right there and it's fully exposed to whatever might be in the atmosphere. So that's why, you know, when you are changing your lenses, really, really protect that camera sensor. It might be putting your hand in front of it if you're gonna be a couple seconds.

I like to change lenses with the camera actually facing down so that way dust isn't settling from the atmosphere like just via gravity onto the sensor. I also just really try to avoid changing lenses in dust, rain, wind, in safari vehicles or on beaches, anywhere that feels like there could be sand or dust in the atmosphere, that's a lot of places.

Just be extra, extra cautious.

Some other practical tips is use your camera's sensor cleaning mode. you can actually tell it to clean your sensor, and I believe it just sends a little vibration through the sensor and it just kind of knocks off any of that

gently affixed dust.

You can also clean your sensor. I don't generally clean them on trips, but I do so when I get back home, usually usually like once every few trips or once a year. But you do need to be very careful with wet cleaning. I've said several times in this podcast that I do recommend people just take the plunge, watch some YouTube videos, see how it's done. but if you're not comfortable with it, you can absolutely have it professionally cleaned. And unless you're in the field 200 days a year, you should be good having it cleaned once a year.

It'll knock you back fifty or sixty bucks, but hey, you're supporting your local camera store, so that's great.

Also, don't panic if there's dust on your sensor. It's it's not like gonna erode the sensor or be a massively bad thing. It's probably not gonna damage it or scratch it. It's gonna show up in your photos and you may have to spot edit a lot of photos to solve that problem there. But just know that dust happens. it can be removed in editing, but really good field habits are the key thing here for preventing it in the first place.

So here's my final takeaway. Your your sensor is indeed the heart of your digital camera, but it's not magic. It is a light gathering tool. but also your sensor is not just a spec on a camera brochure. It's it's the thing that truly determines how your camera receives the world, receives the light, receives the image that you ultimately are making. And when you understand how it perceives the world, you become better at translating what you see.

what you're feeling in that moment and what you want the final photograph to really say. And that's the goal.

We're not going for perfect files. We're not going for perfect histograms. we're not going for noise-free images at any and all costs. The goal here is, of course, better photographs, more intentional photographs, photographs that do justice to the moment right in front of you. So the next time you're out there, whether you're photographing wildlife, landscapes, travel, or just playing around with your camera in your backyard doing some tests, think about those little light buckets. Think about how much light they're collecting, whether they're overflowing, whether they're completely dry and empty.

Think about what your ISO is really doing.

and then make those creative decisions. Because once you understand the sensor, you're not just pressing buttons. You're really working in tandem with the camera. And that's where photography can get, frankly, really, really fun. Well, once again, folks, I hope this was helpful. I hope I made sensors a little bit less mysterious and a little bit more practical and friendly. Friendly sensors. If you enjoyed this episode, one of the best ways to support the podcast is leaving a rating or review on whatever podcast platform you're listening on. You can leave up to a five star review, hint hint.

And if you have questions or ideas for future episodes, or want to check out my editing series and additional photo tutorials, bop on over to my YouTube channel, leave a comment on one of my videos, and I'll see you over there. Thanks as always for listening, folks, and thanks for being part of a really fun wild photographer community and looking forward to talking to you next time.


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Court Whelan

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