A crop factor will effect the field of view of your lens. In the video below I show an example of the difference in distance from the subject to the camera using the Rokinon 35mm T1.5 Cine Lens for Canon VDLSR on 3 cameras with different sized sensors. For the Full Frame camera I’m using the Canon 5D Mark III, for the APS-C camera I’m using the Canon T4i and for my Micro Four Thirds camera I’m using the Panasonic Lumix DMC-GH3.
A full frame sensor will give you a full 35mm image, similar to that of film. The Canon 5D Mark III is a full frame camera and with it we see a full frame field of view. The Canon T4i has a smaller sensor, therefore, the same image, using the same focal length on the same lens, is cropped. The T4i has an APS-C sensor with a crop factor of 1.6. The Panasonic GH3 is a Micro Four Thirds system with an even smaller sensor and a crop factor of about 2. This means that with the same lens, at a fixed distance from the subject, the field of view will look different depending on whether your camera is a Full Frame, APS-C or Micro Four Thirds.
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