Well, not this source. To me, a line is a construction with the background necessary for it to exist as a line. A black line only exists on it's accompanying white background. A white line only exists on it's accompanying black background. Generally, when folks talk about lines, They are talking about the marks made on top of a background. When looking at resolution mathematically in order to determine resolution, one talks about how close one can bring one airy disk to another and still discern that there are actually two airy disks and not one oblong image.
When a diffraction grating is used, one does not refer to the space between the grating lines, they are understood to exist. One only refers to the number of lines (scores or whatever) per unit measure. Of course there may be some in photography prefer to use conventions or references different from other folks who need to refer to resolution, such as astronomers, radar engineers, etc. and desire to view white and black space as separate lines. You can understand why other folks in other disciplines don't. It is easy to determine what is actually being measured. Get an Air Force resolution measurement target, count the number of lines per mm on a specific part of the target. Do the geometry per the target use instructions to determine the number of lines per mm at the film plane. Regards, Bob... -------------------------------------------- "Do not suppose that abuses are eliminated by destroying the object which is abused. Men can go wrong with wine and women. Shall we then prohibit and abolish women?" -Martin Luther From: "Mark Roberts" <[EMAIL PROTECTED]> > "Bob Blakely" <[EMAIL PROTECTED]> wrote: > > >The wording, line pairs per mm, implies two black lines and two white lines > >in as much as "pairs" is plural and also because there are many more than > >two lines in the target. This would mean that line pairs per mm would be > >half of lines per mm. > > Hmm. At least one source I've seen regarded one black line and one white > line as a "pair".
