Full frame vs crop sensor is often the deciding factor for photographers looking to buy new gear.
But do you know why this sensor size debate is so heated?
I’m here to set the record straight and let you know what crop and full-frame sensors are and what they do. And how you can take better pictures with both.
[ExpertPhotography is supported by readers. Product links on ExpertPhotography are referral links. If you use one of these and buy something we make a little bit of money. Need more info? See how it all works here.]
What Is a Sensor?
Your sensor is what records the scene you are photographing. An image sensor or imaging sensor detects light waves and turns the recorded information into an image.
The resolution of your camera is directly influenced by the quality of your sensor. A more expensive and bigger sensor is going to have a higher resolution or megapixel count.
In film photography, the sensor is effectively the film type and speed that you choose. With digital photography, this electronic device decides everything.
It is an important choice when it comes to buying a DSLR, mirrorless system, four thirds or point and shoot camera. Each has its own size and resolution.
When buying one of these camera systems, you want to decide whether you can afford a full-frame sensor or not.
They can be very expensive, but depending on what you photograph and do with your images, you may need one. A bigger sensor means better image quality.
If you are photographing to share on social media, you can get away with an APS-C camera or a smaller sensor.
If you are shooting large-scale commercial projects for large companies or even professional wedding photography, you need a full-frame DSLR with a larger sensor.
The full frame sensor is based on film photography. The size of a 35 mm frame in film photography is 36 mm × 24 mm. Any digital sensor of this size is regarded as full frame.
Since 1909, the 35mm film format has been the standard. When you look at lenses or camera systems, you may hear the term ’35mm equivalent’.
This is just another way of saying full-frame.
If you own a full frame sensor camera system, you don’t need to think about much. A camera such as the Canon EOS 5D Mark IV when paired with a 50 mm ‘nifty fifty’ lens will give you a 46° field of view.
A crop sensor camera system will treat the lens in a different way. It won’t give you the same depth of field or effective focal length.
If a full-frame sensor is 36mm x 24mm, then a crop sensor is smaller. Each manufacturer has a different crop factor or naming system.
The crop sensor was developed as full-frame sensors were incredibly expensive to produce.
By making crop sensors, camera manufacturers could create cheaper, accessible sensors for photographers who didn’t have a professional budget.
Canon has a crop sensor with a factor of 1.6x, Nikon’s crop factor is 1.5x. There is also the Micro four-thirds system, used by Olympus and Panasonic, which uses a crop factor of 2x.
How the Crop Factor Is Calculated
The math to find out the crop factor is simple. If you know the physical size of the sensor, you calculate the diagonal using the Pythagorean Theorem (a² + b² = c²)
Then, you divide the number by the diagonal of the crop sensor. Here is an example on finding out the crop factor of the Canon sensor:
- 35mm / Full-frame diagonal: 36² + 24² = 1872², so the diagonal is 43.27mm
- Crop sensor Canon diagonal: 22.2² + 14.8² = 711.88², so the diagonal is 26.68mm
- Crop Factor: 43.27 / 26.68 = 1.62
Crop Sensor Disadvantages
A cheaper sensor is, unfortunately in some ways, an inferior sensor. There are disadvantages to using a crop sensor.
For one, as the scene is cropped, your lenses work in a different way. A camera such as the Canon 7D Mark II is a crop sensor, meaning it is 1.6x smaller than full-frame or 35mm.
What this means is that your lens is affected by a factor of 1.6x. A 50mm lens on a crop sensor Canon camera (50mm x 1.6) means you are using the equivalent of an 80mm lens.
Standing and photographing a scene with a full-frame camera, and then a crop sensor Canon camera will be noticeably different. Your scene with the crop sensor is smaller by a factor of 1.6.
To get the same view using a crop sensor Canon camera, you will need to use a wider lens or step back. To get a 50mm focal length and 46° field of view, you will need to use a 31mm lens.
In some cases, you will not be able to step back and widen your view. This is why it is very important to know if you have or plan on buying a crop sensor camera.
Crop Sensor Advantages
Don’t get me wrong, there are advantages in owning or using a crop sensor vs full frame camera. The first would be the price. When I shopped around for my first professional DSLR camera, I had two choices.
Either go for the Canon 5D Mark II or the Canon 7D. They were incredibly similar, being released only 1 year apart. The big difference was the 5D Mark II was double the price.
On a plus note, I also found the Tokina lens series DX, which compensates for the crop sensor. This means when I buy a 12mm-28mm lens, it doesn’t have the 1.6x increase.
The second reason is that it increases your lenses focal length. Yes, this was a disadvantage, but consider the advantages.
Having a lens with a multiplication factor of 1.5/1.6 means you can get closer to your subject. You don’t have to physically get closer, as in many cases, you might not be able to.
Photographing the moon with a 300mm lens on a full-frame camera body will give you a focal length of 300mm. If you photograph using a crop sensor, your 300mm lens is actually 480mm.
This means you are 1.6x closer to your subject. This is without having to buy an expensive super-telephoto lens, such as the Canon EF 400mm f/5.6L or a teleconverter.
This also works for up-close subjects. Macro photography is a great field of photography that a crop sensor can help immensely.
If you have a 100mm macro lens, by using a crop sensor, you effectively have a 160mm lens. This gets you so much closer to the insects or flower you are photographing, all at no extra cost.
There is no easy way to decide if a crop sensor for full-frame camera is for you. It will depend on a few things; namely your budget and your cameras’ use.
If you need a full-frame sensor, as you are photographing marketing campaigns, there is no way around it. That is not to say you can’t take amazing, billboard bound images with a crop sensor.
If you are photographing objects very far away, a crop sensor camera gets you closer to them without any extra cost. No need to buy extra lenses or equipment.
I have a crop sensor and photograph street, documentary and portrait photography. These are areas where I had a large space for mobility, moving backward and forwards as I saw fit.
Having an array of lenses means that no matter what you are capturing, it is still possible.
Think of it this way; if your gear kit includes a wide-angle lens, a standard lens, and a telephoto lens, you just need to re-imagine the focal lengths.
Instead of 16mm-24mm, 50mm and 70mm-200mm lenses, you can find 11mm-16mm, 35mm and 50mm-100mm lenses to cover the same focal length.
This works, unless you already have many lenses, and change from a full-frame to crop body or vice versa. I don’t find this to be such a big problem, and you may not either.
Yet, if you need to get closer to your subjects, I would go for a crop sensor camera for the cheapest solution.
Looking for more information about sensors? Check out our new post about equivalence in photography next!