قوة التحديد .. كتاب أسس التصوير الضوئي

Resolution or Resolving Power

The power of definition is defined as the ability to transfer close points or fine lines in the body so that they appear completely defined in the image, and each of them is completely separate from the other. The strength of determination is measured by the number of lines per millimeter that are recorded on the sensitive layer when photographing a test board that has identical lines, each at a distance equal to the width of the line itself. If we denote the thickness of the line with the symbol x, the following equation would be a means to measure the strength of determination.::

The limiting power = 1 over 2x and is denoted as the limiting power (R.P).

As an explanation for this, we assume that a picture of a test plate has contiguous black lines, Figure (175), and the width of each of them is equal to the distance between each line and what follows it. Measure the number of lines per millimeter in the negative. If the thickness of each line is equal to one millimeter, this means that the number of lines per millimeter = 50 lines, i.e. the determination strength is considered equal (50 lines per millimeter).

It is usually symbolized by the following (QT / 1/50 mm)

If the lines of the test board did not appear completely separated from each other, but appeared connected for considerations that we will mention later on, then we cannot decide that there is a defining power.