What the crop? Full frame and crop sensors explained.

  • Example photo of full frame vs crop sensor crop by Jessica Nelson

As with many photographers, I started my interest in digital photography with a smaller and less expensive camera.

I wanted to dabble without spending a ton of money. So in 2007 I bought the Canon 30D.

I knew this camera was a crop sensor, or APS-C, when I bought it and I learned how to adjust the focal lengths of my lenses to make it work for me.

Let’s start with the basics, what is the sensor?

On a film camera, it is the film that collects the light that comes through the camera’s lens to form an image.  In a digital camera, it is the sensor that collects the light that comes through the lens and converts it into electrical signals that are sent to the memory card.  In short, the sensor is the digital camera’s version of film.

What does full frame mean?

A full frame camera has a sensor that’s the same size as a frame of traditional 35mm film.  It measures 36x24mm and is referred to as 1.0x.

What does crop sensor mean?

A crop sensor is literally that- a cropped, or smaller version, of the full sized (35mm) sensor.  Cameras can have a crop factor of 1.3x, 1.5x, or 1.6x.

My Canon 30D has a crop factor of 1.6x which means that it is 5/8th or 62.5% the size of a full frame sensor.

What this means is that my Canon 30D will produce an image with a field of view that is 5/8ths the size of what full frame camera’s field of view will produce. Why do you need to know what your crop factor is? (More on that in a moment.)

You can see the difference between the 30D crop sensor and 5d mark II full frame.

Example photo of full frame vs crop sensor crop by Jessica Nelson

By changing the field of view, a crop sensor changes the effective focal length of your lens and makes it act like a longer lens. But how do you know what the effective focal length of your lens is? This is where knowing what your crop factor is, comes into play.

In order to determine what the focal length of your lens is, on a crop factor camera, use the Focal Length Multiplier: multiply the focal length by the crop factor to get the 35mm, or full frame, equivalent. Here are some examples of this comparison (using a crop factor of 1.6x):

  1. The 28mm lens would act as a 45mm lens (28 x 1.6 = 44.8)
  2. The 50mm lens would act as a 80mm lens (50 x 1.6 = 80)
  3. The 100mm lens would act as a 160mm lens (100 x 1.6 = 160)

There are lots of really great cameras on the market today that have a crop sensor such as the Canon 70D, 7D and the Rebel line (Nikon sells them as well but since I shoot Canon I am only listing those). In addition to having a lower price tag, a potential benefit to shooting with a crop sensor, if you are wanting to do long distance shooting, is that your lens will now have a longer focal length.  (What you previously would have needed a 200mm lens to shoot with a full frame camera, you now only need a focal length of 125mm.)

Eventually, I did update my camera to a full frame but only because I was looking for a camera that handed low light better than my 30D. I needed more ISO Range.

To show the difference between the two cameras I am including some examples using the same three focal lengths.

Before I show the examples I am including a shot of my setup that I took with my iPhone. I decided to shoot these in my little studio with my fabulous model Veronica. I used the exact same settings on each camera (1/125, ISO 100, f/5) and on the tripod at the exact same distance that I marked with a sticky note just in case I moved it. You can see both my cameras, the 5D is on the tripod with my Tokina 16-28 and the 30D is on the floor with my 50mm and my 100mm. Also, please excuse the very boring center comp, I thought it would be easier to replicate everything that way.

lighting and shooting set up of full frame vs crop sensor comparison by Jessica Nelson

Example photos:

You can see that both of these cameras are good for full body photos with a wide angle lens. Further down you’ll see how the 5D (full frame) is a decent length for a headshot where the 30D (crop sensor) is more of an extreme close up. This would be a difficult length in a small studio space like mine except if I was shooting a face closeup or a macro.

Comparison of different lenses on a crop sensor and full frame cameras

The conclusion here is that both types of cameras are good ones for different reasons. I still use my 30D when I want to go birding with my 70-200 and my 5D is amazing for handling low light and taking wide landscape images using a short focal length lens. It all depends on what you want to shoot and what your budget is.


About the Author:

Getting her start in a darkroom as a kid, Jessica Nelson is a serious hobbyist who lives in Maryland with her supportive husband, three camera-tired kids and an energetic rat terrier. She is often seen, camera in hand, chasing her kids around the house to capture their every moment. When they don’t cooperate, she is known to take her passion outside to shoot the beautiful nature that surrounds her, since they can’t protest.


  1. jennifer n. Jan 23 2015 at 10:59 am - Reply

    this is an incredible tutorial jessica!! thank you so much for going over the differences so well…i finally understand now <3

  2. Iris Jan 23 2015 at 11:30 pm - Reply

    Great tutorial 🙂 – I made the mistake to rent a full-frame camera over the holidays. I wanted to play with it and see if it really has a better noise reduction than my cropped-sensor camera. Big mistake, now I can’t get the full-frame camera out of my head! Oh well, hopefully by the end of this year I have enough money to buy the full-frame.

    • Phil Feb 19 2015 at 3:22 am - Reply

      Jay, it has a lot to do with crop factor. Without getting into it with too much detail: pixels are more loosely packed on a bigger full frame sensor so they produce less heat therefore less noise at the same ISO level as with crop factor sensor.

  3. Kerry Feb 11 2015 at 9:15 am - Reply

    Great read! Still dreaming of a full frame camera… but happy with my Nikon D5100. It has been a great beginner camera. I’m glad to actually see the difference in a photo between the two. (Also dreaming about winning the Dream Giveaway!!! Fingers are still crossed!)

  4. Patricia Borgstede Feb 17 2015 at 8:51 am - Reply

    thank you so much for this! I keep hearing about the whole crop sensor issue and have read a few articles but I just didn’t quite get it until now! Thanks!

  5. John Nov 01 2015 at 9:15 am - Reply

    Thank you for this through guide!

  6. Diana Elle Blog Jul 26 2016 at 10:42 am - Reply

    thanks for the tutorial I currently have the canon 30d and need to find the best lens for taking “normal” looking pictures

  7. Donna Wayne Feb 15 2017 at 6:38 am - Reply

    Very nice, thanks! The only cropping I knew so far is like this http://www.paintshoppro.com/en/pages/photo-crop/ while editing but now I learned something more, thanks for the lesson!

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