Full Frame Sensor Vs Crop Frame Sensor

Full Frame Sensor Vs Crop Frame Sensor

If you’re just getting into the world of cameras and lenses, the term “crop factor” and phrases like “this is a 35mm equivalent lens” might still confuse you. Now you don’t have to worry because you are at the right place. Just grab a cup of coffee and follow along with my article. I always try to make tutorials such a way that photography enthusiast can understand easily, so many of the terms and explanations are over-simplified.

How many of you think ““My camera sucks [at this point I assume that you have consumer level camera with kit lens] ,my camera is not able to produce image quality like a pro camera and I need to upgrade.” Don’t be shy, raise your hand. Mine’s up too. I think everyone comes to this point at some time.a

Here I would like to mentioned u that ,it is not the camera but the photographer who makes the difference. But still in order to produce pro quality there are few technicalities involve which I will going to discuss in this article. Another factor which controls the quality of image is ‘lens’, this topic is beyond the scope of this article. I will discuss it on another day.

Sensor Size :

There are mainly two types of camera available in terms of their sensor size. They are Full Frame Sensor (35 mm) camera and Crop Sensor camera.

Full Frame Sensor ( 35mm ) :

Full-frame sensor camera(Canon 5D,Nikon D800 or similar type) have image sensors that are the same size as 35mm film. Full Frame Sensor(35mm) camera also termed as Full body camera. And it is become the standard format for DSLR camera sensor. This types of sensors are typically found in high end DSLR. Now ,why 35 mm? it’s purely due to historical reasons – 35mm was the dominant size for film cameras and cinematography. As for why film cameras ended up with 35mm. It’s certainly not the largest sensor available – a number of companies (Hasselblad, Phase One, Pentax) make “medium format” sensors which are larger than 35mm sensors.

Crop Sensor / APS-C :

When anyone starts digital photography they starts with consumer level camera (canon 700D,Nikon D3300 or similar type).This types of camera has ‘Crop Sensor’. Crop Sensor means its sensor size is smaller than Full Frame Sensor (35 mm) camera. Crop sensor camera also termed as Crop body camera.

What is Crop factor :

Crop factor describes the size difference between a 35mm film frame and your camera’s sensor. For example, if your camera has a crop factor of 2x, it means that a 35mm film frame is twice as large as your camera’s sensor.

Here is a list of current cameras that have different crop factors:

1.5x Crop Factor: Nikon DX (D3300, D5500, D7100 etc.)
1.6x Crop Factor: Canon ( 70D, 7D etc.)

look at the below image to understand the above topics clearly.

How lens capture image:

Let’s see how lens capture an image. Lens is circular. When you attach a lens on your camera body, light enters the lens and forms a circular image, but the image sensor is rectangular, so some of that light is not captured for recording (plz see jagged lines in the image below).

For perfect comparison, let’s attach 50 mm lens on both Full body and Crop body. Now keep your camera at the same distance and position from the subject and capture. You will clearly see that 50mm lens gave us a significantly larger field of view (the area we capture) on our Full body camera where as field of view is much narrower in Crop body camera. On a less expansive DSLR, the sensor is usually smaller and it captures less of the light entering the lens. Essentially, the image is being cropped.

Now fasten your seat belt, we are going to understand the two most important concepts.

Effective Focal Length (Crop factor and Focal Length)
Effective F-Number (Crop Factor and Depth of Field)

Effective Focal Length (Crop factor and Focal Length) :

When you use same lens (in this case it is 50 mm) on both Full body and Crop body. Crop body images appears as if they are zoomed. Means, 50mm lens on a crop-sensor acts like a 75mm lens (on a 1.5x crop sensor, Nikon) or 80mm lens (on a 1.6x crop sensor, Canon).

So, when the differences between full-frame and crop-sensor cameras are discussed, there is an inevitable question about whether the crop sensor multiplies the focal length ( see the image below ).

The answer is “NO”. Because, Crop factors make lenses appear more powerful because the angle of view is reduced. When you fit a 50mm lens onto a camera on a Crop sensor, it’s still a 50mm lens. What has changed is the format of the sensor, which covers a smaller field of view and makes the lens behave like a longer lens.

Now, the obvious question is ” how do we compare Full body and Crop body in terms of lenses?” To understand the relation more clearly the term “Equivalent 35mm focal length /Effective focal length” has introduced. A simple multiplication can easily solve the relation.

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Effective focal length = True Focal length * Crop factor

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“Sensor Size” changes the ‘Equivalent Focal Length’ — not the ‘True Focal Length’ of the lens.

Effective F-Number (Crop Factor and Depth of Field) :

When you use same lens (in this case it is 70 mm), same composition and same Aperture (in this case f/2.8) on both Full Body and Crop Body. Full Body camera will give u much shallower Depth of Field than Crop Body camera. Means defocus area will appear much blurry in Full Body camera. So you might think that Full Body camera is perfect for creamy buttery background (see the image below)

But it is not true. ‘Depth of Field’ never changes with Crop Factor. Means background will blur equally in both Full Body and Crop Body when u use same Focal Length and Aperture. Plz don’t be angry, I know you will ask me ” how can you say such stupid thing? In the above image it clearly shows that Full frame sensor gives much blurry background”.

Ok Ok. Cool down. Let me explain. Though we have maintain same Focal Length and Aperture (f/2.8 in this case), but one important thing we have ignored in the above comparison that is “subject to camera distance”. We all know ‘Depth of Field’ depends on “subject to camera distance”. If move away from the subject ‘Depth of Field’ will increase. So, in the above image, when we shot with Crop Body we have to move away from the subject to maintain the same composition , which definitely in tern affected the ‘Depth of Field’ of Crop sensor image.

To understand relation between Full Body and Crop Body in terms of Depth of Field , the term “Effective F-Number” has introduced. Keep in mind when you do this comparison you have to take consideration of same composition and same f-Number.

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Effective F-Number = Actual F-Number * Crop factor

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“Sensor Size” changes the ‘Effective F-Number’ — not the ‘True F-Number’ of the lens.

Sensor Size and ISO :

If we capture same image with three cameras of different sensor sizes. The ISO, aperture, and shutter speed were exactly the same for all three. You can see, the smaller the sensor size, the noisier the image looks, because smaller sensors receive less total light. Small sensor has a smaller number of pixels, which can affect the overall quality of an image when shooting in low light – it will be less sharp, and digital noise will be more noticeable (see the image below)

Now the obvious question is Crop Factor is Good or Bad?

Frankly speaking it is very difficult question to answer but from my experience I can say, when u shoot indoors or inside a car. You might run out of space . In this scenario, if u use same lens on both body. Full body will give u wider field of view. Unless you buy wide angle lenses made for APS-C sensors. I don’t want to give the impression that full frame cameras are always better. First off, they are expensive, usually a lot more expensive than APS-C based cameras. It’s also important to note that Crop Factor can sometimes help, rather than hinder your shooting. If you’re trying to get a closer shot of your subject but physically can’t move closer, the crop factor will act as a sort of focal length multiplier. For instance, an 85mm lens on an APS-C based camera (with a 1.6 crop factor) will give a field of view of 136mm.

If you would like to know my personal opinion. I would say, “forget everything ‘depth of field’, ‘ISO’, ‘f-Number’. The most important thing I always consider before purchasing camera and camera equipment is ‘price’. Because it is not easy, at least for me, to invest hard earn money at first place. It took almost 6 years for me to upgrade from Crop Body to Full Body. So when u start your photography professionally or as a hobbyist, Crop Body camera is good in my opinion but if you can afford to purchase Full Body then there is no two ways to think.

I hope this article will help you to understand crop factor . Now you are a step ahead from your friends. Impress your friends and strangers alike with your vast crop factor knowledge.

Full Frame Sensor Vs Crop Frame Sensor