The resolution power of 355 lines/mm (Advertised number of lines/mm) is the calculated figure obtained when the conversion lens is attached on the perfectly made master lens without any aberration from the designing point of view. In other words, you can read the test pattern of 355 pair (>Advertised number of lines> pair) of black & white lines written in the width of 1mm. With the low resolution power lens it can not be read the lines clearly separated but in vague gray.
Please note that the resolution power often referred to TV, which counts the number of lines of black/white on TV screen, is different from the above resolution power of optical lens.
