I read recently that engineering types say Lines per millimeter (l/mm or lpmm) whereas photographer types say Line Pairs per millimeter (lp/mm or lppmm).
However, when engineering types say lines per millimeter, they usually mean line pairs per millimeter so 60lpmm = 120 lines.
Confused? Well I am because you never know what the quoted numbers actually mean if the don't say lppmm. Do they mean 60lpmm or 60lppmm?
Maybe it is a good idea to ask the manufacturers, too? They must be interested in objective information...well, as long as they are not from China and as long as we don't raise an issue like doping
After that, why not make a permanent link here and publish it on sites like digitaltruth.com?
I'm sure that they have nothing to be ashamed of, and most people accessing this type of information understand that it's only a starting point.
My dream is a database of all films, showing a standardized example, the film exposed and developed according to the manufacturers' manuals, scanned in a standardized way on a high-end drum scanner and showing small crops of the images on a website. To make it really complex, varieties of the setup using other developers are a mustSo, everyone could get a good impression instead of listening to repeated advertising BS... but it's the work of a lifetime.
As much as I am a recovering tech-geek,
the photographic process buffers the granularity of any film and developer combination.
Handled well, there is not much difference between any ISO class of film, certainly not enough to
be reason to choose, for instance, FP4 over Plus X.
The REAL differences are three-fold:
1. Color response. There are subtle differences between FP4 and PLus-X. And a vast difference between them and the pseudo-ortho signature of APX 100. If you are shooting outdoors, FP4 will just about spare you a light yellow filter to record a toned sky. APX 100 is very sensitive to blue, and getting shadow and sky at once is... well, that's why I have so much experience flashing skies ! But for one film that flatteringly records every complexion of our planet, APX 100.
2. Film curve. FP4 and TMY have never-ending straight lines. Plus X does not. Pick your subject and your desired image, then pick the film that does the dirty work FOR you.
3. Availability. If I can't get it, or worse, if I think I can get it but CANNOT, it is no use to me. Even if it grainless 1000 speed film.
Different developer temperatures, right hand vs. left hand twists of rotation, stainless vs. plastic .......
Paul, which blue filter did you use? 47?
As long as they are all using the same standard and technique, the precise definition and terminology doesn't matter. And I do believe that they are. It's old, established science.
Just to confirm, where you say for example, Fuji Across 200 lines per millimeter, thats means 200 line pairs per millimeter. Yes?
Further research is up to you.
Just to confirm, where you say for example, Fuji Across 200 lines per millimeter, thats means 200 line pairs per millimeter. Yes?
This can be very confusing. One of the issues is that there are at least two charts commonly used to test resolution, the PIMA/ISO resolution target, and the USAF 1951 target. The first expresses resolution in line pairs per millimeter (lp/mm, or LPPM), the second in lines per millimeter (l/mm, or LMM). Just understand that numerically lines per millimeter (L/mm) is double line pairs per millimeter (LP/mm). 100 lines per millimeter (l/mm) is 50 line pairs per millimeter (lp/mm).
Kodak uses the term "lines per millimeter" when discussing resolution.
Sandy King
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