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The Sensor

Lesson 3 from: The Photography Starter Kit for Beginners

John Greengo

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Lesson Info

3. The Sensor

Summary (Generated from Transcript)

The topic of this lesson is the sensor in a camera and how its size affects image quality and camera size.


  1. What is the sensor in a camera?

    The sensor is the light gathering device in a camera that records the light.

  2. How does the size of the sensor affect image quality?

    Generally speaking, the bigger the sensor, the better the image quality and the more light it can gather.

  3. What are the trade-offs of having a bigger sensor?

    A bigger sensor requires a bigger camera, which means bigger lenses, more money, and more weight.

  4. What are some common sizes of sensors in cameras?

    Common sizes include Full Frame, APS-C, Four Thirds, and 1".

  5. How do different sensor sizes affect lenses?

    Different sensor sizes require different lenses since they have different image requirements.

  6. Why is it difficult to have a common language when discussing sensor sizes?

    The naming conventions for different sensor sizes are illogical and can be hard to understand.

  7. How does a Crop Frame sensor affect the image compared to a Full Frame sensor?

    A Crop Frame sensor crops the image, resulting in a narrower field of view compared to a Full Frame sensor.

  8. What are the advantages of using a Crop Frame sensor?

    Crop Frame sensors can provide a natural boost in focal length, making them preferable for telephoto photography.

  9. Should I upgrade to a Full Frame sensor?

    Upgrading to a Full Frame sensor has significant costs, including the need for larger and more expensive lenses.

  10. What should I consider when choosing a camera?

    Consider factors such as hand size, comfort, and the number and size of lenses you need.

Next Lesson: ISO

Lesson Info

The Sensor

Let's talk about the sensor in the camera. So the sensor is obviously the light gathering device that records the light. And the first thing to note, for those of you who might be new to photography, is that there are lots of cameras and there are lots of different sizes of sensors that might be in these cameras. And there's a trade-off here. The bigger the sensor, generally speaking, the better the image quality, the more light that it's gathering, but it's also a bigger camera, which requires bigger lenses, which means more money and more weight. And so, finding that compromise, we've mentioned this before, compromise in the balance of finding what's right. And so what's right for you may be completely different than what's right for somebody else. Somebody else might say, oh, you need this. Well, do you need that, or do they need that? And so you gotta be clear as to what your needs are as a photographer. So let's take a look at some of the options in here. Even though a lot of peop...

le aren't shooting film anymore, it's still based on film because of the history and legacy of photography. We shot film for many, many years, and 35 millimeter film was, let's call it the Goldilocks film. It's just the right size. It was small enough that we can make a camera, hang it around our neck and trot around Europe for weeks on end, and it was big enough that we can make a poster-sized enlargement from it, so it was just the right match. And they, of course, made cameras that were bigger and smaller to address different needs. And so, when we made the change from film to digital, most of the serious photographers just wanted a digital, full-frame camera that used all their same lenses, and that was really nice, but it's kind of expensive. And so they started making sensors that were smaller in size where they could produce them for less money and so that you could have cameras that were affordable, and regular people could buy. And so, different manufacturers went different routes with different size sensors. Now, one of my biggest complaints in photography is that I'm not the king of photography and I don't make all the rules, and the titles and names of sensors is the most illogical, stupid thing you may ever encounter in your life. So we start with Full Frame, which refers to film and old technology. APS-C, which also refers to an old film that practically nobody shoots anymore. Four Thirds deals with an aspect ratio. 1", now we have numbers measuring inches, and then we have these fractions, which are really very hard to understand. I'm sorry. And that's all I can do is apologize. It's not what I wish. I think it's a lot easier if we were to measure these the same way we do our computer and TV screens, just diagonally, and you figure it out. So something in your phone is gonna be about six millimeters in size, and I think most of you know how big six millimeters is. That's pretty small there. Full Frame sensor is gonna be 43 millimeters from corner to corner. Once again, the larger the sensor size, the more light that it can bring in. Now, when it comes to interchangeable lens cameras, they tend to kinda concentrate on the larger size sensors because that's gonna give you a better image quality. The Full Frame sensor is very popular now. It's become more affordable. They've streamlined some of the production cost. I really don't feel comfortable saying that a $3,000 camera is cheap, but at least it's not $20,000, where it was many, many years ago. And so there's a lot of manufacturers that make Full Frame cameras. That's where a lot of the professionals who have cameras like them, because it's just a very efficient place to be for many reasons. The most popular place for many consumer cameras is in something known as a Crop Frame camera. A 1.5x Crop Frame camera. Now, what's 1.5x about it? It's smaller. Shouldn't it be something smaller? Well, it's the relationship between 43 and 28 millimeters. And so, in order to get from one to the other, there's a crop factor of 1.5x. And this is where I would say the majority of students in my classes, this is where they are with the types of cameras that they have. Canon, they went slightly different. They're at 1.6x. It's not really that big a deal. It's just slightly different. And then for people who really do like smaller cameras and smaller lenses, there's a system called the Four Third system, which uses a smaller sized sensor. And as you might guess, this is a compromise. Image quality is not quite as good as the larger size sensors, but the lens size and the camera size gets to be quite small and for somebody who really prizes low weight, small, compact system, it's a nice system on there. Now, the problem is that when we listen to instructors, when we read a blog article about photography, we need to have a common language so that we can all understand that we're talking about, and it's kinda hard to keep saying, well, if you have this, it means this, and if you have this, it means this. And so, what happens is because most photographers who are pretty serious; the ones that are making the videos, the ones that are writing the articles and writing the books, most of them use Full Frame. That's the system that a lot of people talk about, but that's definitely not the most popular system. So it's not a democracy that we're working in here. Alright? So let's talk about some of these differences here. We're gonna look at a Full Frame sensor, and you can imagine an image coming in and being on that sensor, okay? Now what would happen if we use a Crop Frame camera but the lens in our position, everything else stays the same? So let's go ahead and put on a 1.6x Crop factor here with a smaller size sensor. Now, you might notice a slight difference in the image. Alright, we've pointed it in the same area. Kinda similar but doesn't have as much space off to the side and so this is the effect of a Crop Frame sensor if you use exactly the same lens, alright? And so this is why they have designed different lenses for the different camera systems out there, depending on what type of sensor that it has in there. Now, this is Full Frame image was taken with a Full Frame camera. In fact, it was taken with a 16 millimeter lens. 16 to 35 at 16. If you said, well, I like that image, but I don't have a Full Frame camera; how do I get that image? Well, this is where you figure out the Crop Factor in there. You can get that with a 10 millimeter lens. A 10 to 22 millimeter lens, and I hate to throw some math on you, but we gotta do a little math in photography. And so 10 times the crop factor of that system is the equivalent of the 16 over there. So something that we talk a lot about in photography these days is equivalence. And so, one person is shooting Full Frame, somebody else is shooting in a Crop Frame, but something is equivalent. They're different numbers, but they equal the same result, essentially. And so, in this particular case, in my mind, it kinda looks bad for the Crop Frame. Because you don't get as much from side-to-side, and you gotta go out and buy a special lens. Well, let's explore this from a different perspective, meaning telephoto. We were using our Full Frame. We have our subject. And what would happen if the photographer next to us was using a Crop Frame camera to take the same photo? Well, their pixels are gonna be more focused on our primary subject in this photograph. We don't need all this extra area on the outside. So for people who shoot telephoto, the Crop Frame is kinda this natural boost to get you a little bit longer lens. Sports photographers, bird photographers, wildlife, action, all of those photographers kinda like these Crop Frame cameras 'cause they're able to reach out a little bit further. So if you wanted to take a shot like this, you could do it maybe with a 300 millimeter lens. And so here's some of the stats on what that lens is, and that's something that's obtainable, I think, by many photographers out there. But as we go through the sensor size, I know some of you are gonna be thinking, well, the pros are mostly shooting Full Frame. Maybe I should get more serious and get a Full Frame sensor. We all have this tendency to wanna upgrade our system. And you can do that. You can certainly upgrade. Let's look at this case, what it would take to upgrade our system> Now, if we wanted to capture that closer up image with a Full Frame camera, we're gonna need a different lens. We're gonna need a bigger lens than we had over here 'cause we have a bigger sensor. Let's figure this out. We started with the 300 millimeter lens. It's got a 1.6x crop factor, which means we now need roughly a 500 millimeter lens, which they do make. It is twice the lens, three times the weight and seven times the price, okay? Upgrading has significant costs to it. You know, when you get into a bigger house, you got more roof, you got more carpet, you got more gardening you gotta do. More insurance, more paint. Everything is more when you upgrade. And so, there is this constant battle back and forth in the world of photography of Full Frame is better, but it's more expensive, and it's bigger, and it's heavier, and it's a matter of what's right for you. And the camera sizes, I have a Full Frame SLR right here. I have a Full Frame Mirrorless, and then I have a Crop Frame Mirrorless. Which is kind of interesting is that, if you compare the Full Frame Mirrorless and the Crop Frame Mirrorless, well, they're about the same size. In fact, the Crop Frame is a little bit bigger. I put a little bit bigger grip on here because I wanna have a nice grip on the camera as well. When it comes to finding the right camera, one thing is kind of pretty definitive, and that's your hand size. What feels comfortable in your hand? And doesn't matter how big or small the sensor gets. This is what most photographers are comfortable handholding and working with. And so you wanna get a camera that's comfortable in the hands and then the next factor is figuring out how many lenses you need, and how big that package is gonna get. And so, when figuring out the perfect camera, don't look for the best camera, 'cause that does not exist. You wanna find one that fits your needs that you like to work with, and that's gonna be the best choice for you. So, once again, be aware that there's lots of different cameras, lots of different sensors, and yes, the image quality does get a little bit better when you get up to the higher sensor sizes. But for most people, take your phone as an example how good is your phone at basic, simple picture-taking when it comes to image quality? And it's using a tiny little sensor. And so, you can get very good image quality off of a very small sensor. If you're pushing the limits of your photography in some way or another, that's when a larger sensor may come in handy. I'm just wondering, I mean, we all have cameras at home. How would we figure out what our sensor is? It's probably best just to do an Internet search on your camera and sensor size. It's usually listed in the instruction manual, and I'm sure you've read and memorized the entire instruction manual from beginning to end. It's usually listed at the tail end. It's not listed on the cameras, but it's one of those things that, once you're into cameras, it becomes a very important thing even though it's not listed directly on the camera anywhere. So yeah, just type in your camera's name and sensor size, and it will probably pop up with the right answer right away.

Class Materials

Bonus Materials with Purchase

Photography Starter Kit Outline

Ratings and Reviews

Kanoelani Patenaude

I am a pro photographer in my dreams, where I know the in's and out's of my camera; however, reality proved differently, as real life would tell you, I was a deer caught in headlights just looking at my new 7D Mark II. I am a photographer enthusiast without the skills, but a lot of love for the moments one, or the profession/hobby of it can capture. I mostly shoot my husband, friends, and community surfers in the lineup, and of course, my children, who rarely sit still. Thus, I switched from Nikon to Canon, venturing on the 7D Mark II for the grand reviews of how stellar of camera it is for action shots (surfing, and kids, this was a no brainer). That said, and overwhelmed with the way beyond my skill set, but noted desire and aspiration to grow, I made the purchase, and sought help rather quickly as I wanted to feel confident with what I was utilizing to capture the best memories possible. I came into this John's courses knowing the "on/off" button, and "auto" shoot mode. I came out of the course feeling like the pro in my dreams, and ready to shoot manual. John's teaching style is on point, and his detailed visuals are a huge plus. My first shots post this photography kit course, I thought were great for my first educated shoot, and shockingly, I even received and email from one of the sponsors of the surfers I captured, asking if they could use my image for their sites and publications. Not bad for a newbie. Though, my intent was never a business purpose, I did not know if I should charge a small fee, or give it for free. I don't mind free as it's not my business, yet I don't want to ruin it for any professional photographers in town doing the same thing that are charging. Perhaps another course to help me with that. I highly recommend courses by John Greengo! Thank you so much, John!


I'm not sure my first review posted. But I LOVE this class! John Greengo is a great, engaging teacher who is really adept at representing the concepts visually and excellent at explaining them verbally. I love how he goes through examples with photographs he has taken. Even though I only have a Nikon Coolpix digital camera, it does have Manual, Shutter priority, and Aperture priority modes. Through his class I've gotten a really good sense of how to balance ISO, aperture, and shutter speed. It's a great overview for me especially since I am new to photography, I can play around with some of these settings, and I have a greater understanding of what I might need in a higher level camera in the future. Money well spend! (For $29, this is an absolute steal). John Greengo is an awesome teacher and I hope to take more of his classes in the future!

Megan Wagner

John is extremely articulate and is a great teacher with lots of visual aids and metaphors to help understand photography. I have been doing photography for a few years now and this class was a tremendous help in boosting my knowledge and refreshing my memory in multiple aspects of photography. The graphics that John uses are helpful and he even goes through images and asks which settings would be best to use and will go through the why. He makes things easy to understand and is very clear about the information he provides. I am so glad I took this course and I would highly recommend it even to an experienced photographer. Thank you John Greengo!

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