Depth of field is the amount of front-to-back sharpness in a photo and it variesapertures (f/2.8, f/4). All things being equal, smaller sensor formats (APS-C and Micro Four Thirds) produce more depth of field than full-frame and medium-format. Focal length plays a part, too: shorter lenses give more depth of field than longer lenses. That’s the practical truth, but if you kept the subject the same size in the frame as you changed from focal length to focal length, then the depth of field is the same. This is shown in the images above, which were taken at different focal lengths, changing the camera-to-subject distance to keep the subject the same size.
