aps-c vs full-frame

01 The crop Factor

Digital SLRS have either a full-frame sensor – so-called because it matches the size of 35mm film – or an APS-C format sensor, which is slightly smaller (36 x 24mm vs 23.6 x 15.7mm). Aps-c-based DSLRS, such as the EOS 750D, 7D Mk II and 80D, are also known as crop-sensor cameras. This is because the APS-C sensor only captures the centre portion of the frame seen by the lens, just as if the full-frame image had been cropped afterwards. In terms of the amount that is cropped, Canon DSLRS zoom to 1.6x.

02 FULL-FRAME TERMINOLOGY

Canon crop-sensor lenses are known as EF-S, and full-frame as EF. EF-S lenses can’t be mounted on Canon DSLR full-frame bodies because the image would be vignetted too much – the edges of the camera sensor would be obscured by the lens itself. Full-frame Canon DSLRS include the EOS 6D, 5D Mk IV and 1D X Mk II.

03 changing VIEWPOINTS

Focal length numbers can be confusing, especially when you factor in the sensor size. Place a 50mm lens on a full-frame camera and the angle of view will be a traditional 50mm view – a spread of around 40 degrees. But put the same 50mm lens on a DSLR with an Aps-c-sized sensor, and the angle of view will tighten to around 26 degrees; that’s equivalent to a 80mm focal length on a full-frame body.

04 sensors and DEPTH of FIELD

As well as the angle of view, sensor size also has a bearing on depth of field. The larger the sensor size, the less depth of field. This is why cameras with small sensors, such as smartphones, find it harder to produce a shallow depth of field, and perform poorly in low light. It’s also why large-format 5x4 cameras need apertures that reduce to f/64 for front-to-back sharpness.