Full Frame vs APS-C: What is the Difference?

This is a guide covering Full Frame vs APS-C.

This whole debate about full frame vs APS-C has been raging since prehistoric ages. Well, not exactly prehistoric but since the dawn of APS-C cameras.

The argument became a hot topic when digital cameras came into existence because when digital SLRs came about APS-C cameras were the beneficiary as the smaller sensors were inexpensive to make.

This discussion aims to find out whether this discussion about full frame vs APS-C is still valid in 2021. They both have their advantages and disadvantages.

The kind of sensor that you should invest in will depend on a lot of parameters.

Let’s discuss all of those and while we do that, we shall also burst some myths around one being better than the other.

Ok, so grab a cup of coffee, and let’s get started.

Sensor Size

The biggest point of difference between an APS-C sensor and a full-frame sensor is the size of the sensor.

If you take a 20 MP APS-C sensor and compare that with a 20 MP full frame sensor because the full frame sensor is bigger and also the individual pixels or light receptors are larger, they can capture a lot of light compared to the light receptors on the APS-C sensor.

Full Frame vs APS-C

Low light performance

There are several advantages of that (the ability to capture an additional amount of light) but the biggest advantage is better low light performance.

Or that’s what people who shoot with full frame cameras will tell you. That is not entirely true these days.

Sensor technologies have evolved in the last ten years or so and one of the benefits is improved low light performance with smaller sensors even when those are packed with a lot of light receptors.

So, if you compare a full frame camera from five years ago with an APS-C camera that was launched in the last year or so, there is a good chance that the APS-C camera will outperform the full frame.

It is pertinent to mention low light performance is no longer just about sensor size. A lot of other factors also come into the equation.

Sensor architecture, whether it is a BSI design if it is a stacked design, and whether it incorporates a dual-gain technology all determine low-light shooting capabilities.

Full Frame vs APS-C

Crop factor

Sensor size also has a bearing on another parameter and that is the crop factor. To define the crop factor, we can state that it is the ratio of the dimensions of the sensor size when compared to a full-frame camera.

In layman’s terms, because of its smaller size, the smaller APS-C sensor utilizes only a portion of the image that comes through a lens.

What it means is that when you mount a lens on an APS-C Nikon camera, the smaller sensor will not use the whole image it will only use a portion of it.

When you look at the image shot with the APS-C camera it will appear as if you had used a longer lens. The image will appear zoomed in.

This is why technical details of lenses that are possible to be mounted on crop cameras (APS-C cameras) include ‘Effective Focal Length’.

There are two major crop factors one is the 1.5x which is the Nikon APS-C camera format and the other is the 1.6x which is the Canon APS-C format.

Crop factor and its effect on image quality

The crop factor has an unexpected advantage in terms of how it positively affects image quality.

Really? How is that? Well, a lot of the cheaper full frame lenses are not the sharpest at their edges.

The center of the lens is a different question though. This is why when you use a crop sensor camera with a full frame lens you use the sharpest bit and leave out the fuzzy part.

That automatically improves image quality.

Full Frame vs APS-C

Crop factor and effect on Field of View

Notice there are two terms associated with a lens when you read the specifications. One is the Angle of View (AoV) and the other is the Field of View.

These two terms are often used interchangeably though they are not to be confused as one.

AoV is the extent of the scene that you capture with your lens. It is what the lens can see. A wide-angle lens will have a wider angle of view (thus the name) and a telephoto lens will have a shorter angle of view.

On the other hand, FoV denotes the slice of the scene that a particular sensor and lens combination can capture.

That means both sensor size and the focal length in use have a bearing on the FoV.

In other words, the Crop Factor affects the Field of View (FoV).

Depth of field

Depth of field (DoF) denotes the extent of the scene that is acceptably sharp.

Sometimes it is also referred to as the distance between the closest and the farthest objects in a frame that is acceptably sharp. Depth of field is affected by the size of the sensor. I’ll explain why.

I have already mentioned how sensor size and crop factor will affect the FoV. With the same lens, a full frame camera will capture a wider portion of the scene.

That means it will offer a wider FoV than what is possible with an APS-C camera.

With the aperture remaining the same, the APS-C camera’s crop factor will produce a tighter image with a smaller FoV and with it a larger DoF.

So almost everything will be in focus behind the subject.

On the other hand, a full frame camera will produce an image with a shallower depth of field.

If you want to replicate the image shot with an APS-C camera on a full frame camera you will have to move closer. As you do so your FoV becomes narrower and the DoF becomes shallower.

I know at this point you might be thinking if it is a good idea to shoot portraits with a full frame body.

That is a good idea and a lot of photographers do prefer to use a full frame body for shooting portraits because it is easier to create that shallow DoF.

But on the other hand, it does not mean that everyone shoots landscapes and architecture and interiors (or for that matter street photos) with an APS-C camera.

That may be easier to do but is not always the rule. A full frame camera will find itself useful in all the above genres just as much will an APS-C camera.

Full Frame vs APS-C

Focal length and sensor size

A typical myth is that sensor size changes the focal length of a lens. That is not true.

There are better chances of finding the Yeti if you try rather than trying to establish that focal lengths changes when you switch to a crop body.

Focal length is a physical attribute. It means the distance between the optical center of a lens and the sensor at the back of the camera when the camera is aimed at infinity.

Focal length as a physical attribute will never change regardless of the size of the sensor behind.

What changes, however, is that when you mount a lens on a crop body, the sensor utilizes a smaller portion of the image coming through the lens.

The effect of that is that the image appears zoomed-in or that a lens with a longer focal length has been used.

That is why when a lens is used on a crop camera the ‘Effective’ focal length is also mentioned.

You can easily figure out the effective focal length by multiplying the crop factor with the actual focal length.

For a 50mm lens, the effective focal length on a Nikon APS-C camera is 50 x 1.5 = 75mm. That on a Canon APS-C camera is 50 x 1.6 = 80mm.

Full Frame vs APS-C

Large prints

Full frame cameras have the real estate to pack in an incredible amount of sensors or light receptors.

APS-C cameras also pack in a lot of sensors but they tend to get too cluttered and that often creates issues of noise.

Despite sensor technologies improving quite a lot in the last decade, people still prefer full frame cameras when it comes to choosing a higher resolution camera.

They argue that full frame cameras make better images. They say that these cameras have better dynamic range and so on.

None of that is true. Even if you need to print large or shoot images for a publication, an APS-C camera is just as capable of shooting those as do a full frame camera.

Full Frame vs APS-C

Cost advantage

It is costs less to manufacture APS-C sensors and that is a big reason why cameras with APS-C sensors are inexpensive.

If you are an amateur or somebody looking for an entry-level camera an APS-C camera sounds like a better bet compared to a full frame.

A lot of people these days shoot only for Instagram and for that kind of photography even a mobile phone is good enough.

So, you can save a few hundred bucks by not buying a full frame camera. you can even use that money to buy some good lenses.

Full Frame vs APS-C

Final Remarks

As you have just seen it is not about full frame vs APS-C cameras. None has a clear advantage. Even if there is it is actually very small.

A professional photographer can shoot with an APS-C camera and get stunning results much the same way he or she can with a full frame camera.

Notwithstanding, the general trend is to invest in an APS-C camera when someone is just starting out and then gradually move on to a full frame camera.

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