Subrata Sarkar

Crop Sensor vs Full Frame – The truth

A quick look back to old Analogues

In the age of analogue or film cameras, we used film rolls. They needed to be inserted through back side of the camera. There was a dedicated reangle between the shutter and the physical film which used to exposed the film to incoming light.

Let’s get back in time and take a look how the cameras actually look like in those days.

Photo by Immo Wegmann
Photo: Flickr

To the left is a typical analoag camera and film rolls. We need to load the film strip inside the camera for taking photos. To the right, you can see the inside back of the camera with the lid opened. The rectangle in the middle of it is the area where films get exposed. The size of this reactangle used to be 36 mm wide and 24 mm high, which is exactly the same as each film unit. In other words, the expose area and the film both had exact same sizes!

What does “FULL” mean

In digital era, cameras having sensor of size equal to 36 mm x 24 mm, are FULL FRAME cameras. Camera manufactureres are still using this good old size as the reference point for building full-frame sensors. Think the sensor in a digital camera as individual film unit of a film strip of the analogue system.

And What does “CROP” mean

A sensor having size less than a full-frame, is known a crop sensor. Unlike FULL-FRAME sensors, CROP sensors do not utilize the entire 36×24 sq. mm. area. In fact, they use a certain area of it. This “certain area” is called the Crop Factor. What basically CROP sensors do is center-crop the scene (image) and produce a larger object. The following illustration helps to understand what exactly happens inside a full-frame sensor and crop sensor (often called APS-C sensor) camera body.

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