Crop Sensor vs Full-Frame: Everything You Need to Know

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Crop Sensor vs Full-Frame: Everything You Need to Know

Have you heard the terms “crop sensor” or “full-frame”?  Are you feeling a little in the dark about what they mean?  Don’t worry – photography has its own jargon.  Before you know it, you’ll be throwing out photography lingo like no one’s business.  But for now, let’s talk about crop sensors and full sensors and which one might be right for you.

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I remember when I first started learning about the fancy digital camera I had.  My husband purchased it for me when I had my last child almost 12 years ago.  It was a lovely camera, a Canon Digital Rebel XTi, my first digital DSLR, and boy, was I excited to use it!  Of course, in those days, I only knew how to turn it on, load the memory card, put the camera in Auto mode, and push the shutter.  I certainly had no idea what the sensor was and what it meant for my photos!

My old faithful Canon Rebel – a GREAT beginner camera model – Crop Sensor

Before Crop or Full

The first thing I had to learn was to get my camera off of auto mode and into one of the manual modes.  If you need some instructions, click here for Your Ultimate Guide to Shooting in Manual Mode.  You won’t be sorry – it will completely change the way you take photos!

Time to Upgrade!

Eventually, after lots of practice, I mastered shooting in manual mode and began really using that camera to its full extent.  It wasn’t long before I was ready to upgrade from my Canon Rebel into something with more features.  As soon as I started researching new cameras, I started getting the question, “Do you want a crop sensor or full-frame?”  Yikes!  What the heck does that mean, and how am I supposed to know what I want!?  Lots of studying later, I figured out the difference.  Now I’d like to share all of that research with you.  Here is your primer on the two kinds of camera bodies most commonly available and which one is right for you.

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What’s a Sensor Anyway?

The first thing you need to know is what purpose the sensor serves in the camera.  Before digital was the hot new thing, we used film to capture an image inside the camera.  With the advent of digital photography, film was replaced with a digital sensor that captures our image and turns it into a digital file.

The sensor is located at the back of the inside of the camera body.  The light comes in through the lens glass, passes through the aperture blades, then through the shutter and onto the sensor, where the sensor records your image.

Diagram of the inside of a camera

You can imagine that since the sensor captures the image, it is one of the most important factors to consider when upgrading your camera body.  Unlike lenses, which can be popped off and changed, the sensor lives inside the camera body and cannot be switched out.

Size Does Matter…

Now that you understand the purpose of the sensor, let’s talk about the sizes.  There are several different sensor sizes, but the most common two are Crop and Full.  The three major camera companies, Canon, Nikon, and Sony, carry both of these styles.

A full-frame sensor captures an image in the size equal to that which was captured on 35mm film.  As you might infer from its name, a crop sensor is smaller than a full sensor.  It has been “cropped down” from the size of the larger, full sensor.  They share the same aspect ratio of 3:2, but a crop sensor is smaller than full; therefore, it only captures a portion of a full sensor’s view.

lighthouse with crop and full sizes overlaid across the image

You can see by the numbers above that crop sensors come in several different sizes.  Before purchasing a crop sensor, do your homework and find out the crop factor for the camera you’re looking at.

Crop? Full? What does it mean for Me?

It’s great to know where the sensor is and that there are different sizes, but all this great information only helps if you know how it will affect your photos.  The first thing you need to be aware of is how the crop factor affects your lens’s focal length.  Simply put, a crop sensor camera will feel like it is zoomed in closer than a full-frame camera.  In fact, it is not zoomed in, but because the smaller sensor only captures a portion of what you’re seeing, it feels like it is.

Here’s an example.  Imagine that you are taking a photo of the scene below with a crop sensor, in my case, a Canon 70D, which is the APS-C.  You will see this view:

Waterfall scene taken with crop sensor camera

Take the lens off and put it on a full-frame camera, in my case a Canon EOS R Mirrorless, and you will see this view:

Waterfall scene taken with a full-frame camera

Can you see how this gives you the illusion of a closer zoom?  It’s actually not zooming any closer but rather cropping off the scene’s edges due to the smaller sensor.

Because of this crop factor, lenses will perform differently on a crop sensor than a full-frame.  For example, when you use a 50mm prime lens, you will have the illusion of a tighter zoom.  Instead of a 50mm focal length as the lens suggests, the crop factor gives it the appearance of a 75-85mm focal length.

Now for the Math Part

If you haven’t figured it out by now, I will break it to you as gently as possible.  Photography often requires some math.  Don’t worry – it’s not difficult when you know what formula to use, and lucky for you, I’m gonna give it to you right now!

When you need to know your lens’s actual focal distance, here’s what you need to know.  On a full-frame, it will be equal to the focal length of the lens.  Simple, right?  A 50mm lens has a 50mm focal length.  For the crop sensor, refer to the graphic above and multiply according to your sensor’s size.  When shooting on a Canon, multiply the 50mm lens by 1.6, which results in an 80mm focal length.  For perspective, this means to get equal focal distance on the two cameras, you would need to shoot 50mm on a crop sensor and 80mm on a full-frame.

Why should you care about focal distance?  Because it makes all the difference when it comes to depth of field and bokeh.  If you’re using that full-frame camera with your nifty-fifty, then you’ll get a shallower depth of field (more bokeh) than on the crop sensor.  Shallower depth of field is traditionally celebrated for portraits or macro work but less desirable in landscape or architectural shots.

If you’re considering an upgrade, then you’ll want to consider this, knowing that your lenses will behave differently from crop to full.

Some info about Pixels and how they work

Since crop sensors are smaller than full-frame sensors, they usually have fewer pixels, aka a lower resolution.  However, it becomes a little easier to understand how the pixels work affect resolution if we compare apples to apples.  Let’s say that the two cameras you are deciding between have the same number of pixels (resolution).

Since crop sensors are smaller than full-frame sensors, they usually have fewer pixels, aka a lower resolution.  However, it becomes a little easier to understand how the pixels work affect resolution if we compare apples to apples.  Let’s say that the two cameras you are deciding between have the same number of pixels (resolution).

Dynamic Range

When a full-frame camera has the same pixel count as a crop-sensor model, the full-frame will give you a bit of a more extensive dynamic range than the crop.  What is dynamic range?  Wikipedia defines it this way:  “the ratio between the largest and smallest values that a certain quantity can assume.”  Click HERE for a great article that explains dynamic range in detail.   The flipside of a higher dynamic range is that the crop sensor may allow you to see more details because the same number of pixels are capturing a smaller view.

Low Light

Again – assuming the full-frame and crop sensor cameras have the same number of pixels, a crop sensor will produce a bit more noise in low-light situations than a full-frame model.  Why?  Because even though the pixel count may be the same, the sensor in a full-frame is larger. Therefore the photoreceptors/pixels are also larger and collect more light.  More light means less grain.  If you find yourself shooting in low-light situations regularly, you might be ready to skip the crop sensor and go straight for full-frame.  With full-frame, you can raise your ISO higher and still capture less-grainy images.

File Size

This one is simple.  More pixels equals a bigger file size.  This is important if you are going to print large images.  Anything sized 8 x 10 or smaller will print just fine with any entry-level crop sensor DSLR camera model.  If you plan to print something wall-size to hang over the fireplace, then you may want to consider a full-frame.  Just remember – the bigger the file, the more space you’ll need to store the files on your hard drive.

Summing It AlI Up

When I’m researching, I love to make lists, so here is the list of pros and cons I made when I was shopping for that first upgrade.

Crop Sensor Summary

  • Lower Price
  • Less expensive lens options
  • Smaller Size, so less bulky and lighter
  • Further reach with lenses (great for sports, action, wildlife shots)
  • Smaller file size takes up less storage space on your hard drive

Full-Frame Summary

  • Better Low Light Performance
  • Broader Dynamic Range (better variety of colors and tones)
  • Shallower Depth of Field (more bokeh at a closer range).
  • Wider angle of view (great for landscape and architecture).
  • More expensive lenses. Some crop sensor lenses will work on full-frame cameras, but most will yield a reduced quality image.  The price of upgrading to full-frame lenses can be restrictive.

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So What is Your Opinion?

Many pro photographers will steer you toward a full-frame camera and tell you it’s better.  However, with today’s technology, you will achieve gorgeous photos just fine with a crop sensor.  Don’t feel pressured to purchase a full-frame if you’re not ready or if you don’t have the budget for it yet.

I chose to upgrade in steps, meaning I decided only to spend what was necessary to get the features I knew I would need.  Much of my early photography was related to my family and kids in sports, vacations, etc.  It just didn’t make sense for me to spend the extra money to get a full-frame with so many features I didn’t even know how to use when I was a hobbyist.  After all, it is far more critical to understand how to use the camera you have than to have a full-frame sensor.

I finally upgraded not long ago to a full-frame.  I have been shooting professionally for a couple of years now and find myself doing plenty of event photography in low-light situations where the full-frame outperforms my crop sensor.  Besides, I was outgrowing the number of extra features my crop-sensor camera had available.  Had I skipped the mid-grade camera body and gone straight to full-frame, I would have been overwhelmed at the many features I didn’t understand.

As a bonus, by upgrading in steps, I now have a second camera body on hand for my professional shoots.  I like to keep a wide lens on one body and a close lens on the other and shoot with both.  In the end, the most critical point is to know what you like to shoot, ask questions of a trusted photographer, and be confident in your decision either way.

I would love to know how I can improve this blog for my readers. Would you mind taking this short anonymous survey to share your thoughts?

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2 thoughts on “Crop Sensor vs Full-Frame: Everything You Need to Know”

  1. That’s a fairly well balanced article. I would point out a few things that you could consider. With Canon/Nikon/Sony the crop sensor lens selection is pathetic, you have to go up to full frame lenses often to get more lenses beyond the slow kit lenses. This add a lot of weight and expense, often prices and weight that may be two or more times greater.

    There are other crop sensors with a full line of very good lenses, in particular Micro Four Thirds (MFT) from Olympus and Panasonic, and APS-C from Fuji. Going this route allows you to get high quality gear at a much lower price. I would also add here that these three companies introduced almost all the technology that the big three are finally implementing. But, the little guys have been moving even further. I shoot Olympus cameras, and they are far, far more advanced technically then anything from Sony, Nikon and especially Canon.

    Moral of the story, going bigger isn’t always better, especially if you are on a limited budget or weight is an issue.

    • I agree that going bigger isn’t always better, Bob! You have added some great points to consider here. I shot with an Olympus for a weekend not long ago and was quite impressed. I wasn’t ready to make the change from my Canon, however, and I love the options Canon offers me about as much as you probably love your Olympus! I love that there are so many options out there, don’t you?


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