Field

An area in the video; it is one of many still images displayed in sequence to create the impression of movement on the screen. Two areas consist of a video frame.

When fields are viewed on a video monitor, they are "interlaced" such that the contents of one field are used on all odd-numbered lines on the screen and the other field is displayed in even lines.

Converting fields to a still frame image requires a process called deinterlacing, where missing lines are duplicated to reconstruct the information that would be contained in the discarded field. 

However, deinterlaced images do not have the resolution of the full frame, as each field contains only half of the full-frame information.

The Definition of Depth of Field;  it is the clear area in front of and behind the sharpened subject (it can be an object or a person) in a photo or video.

Three things determine depth of field; the first and most important of these is the aperture, the other is the focal length of the lens (mm value) and the distance of the camera to the subject.

As you open the aperture (lower the f-number), the depth of field narrows; The smaller the aperture (the higher the f-number), the wider the depth of field.

After the diaphragm, the most important criterion affecting the depth of field is the focal length. The higher the focal length, the narrower the depth of field, and the lower the focal length, the greater the depth of field.

Also the distance from your camera to the subject (object or person) you are photographing affects the depth of field. The depth of field narrows as you get closer to the subject, and the depth of field expands as you move away from the subject.