andrew_b7

<p>Ditto that Glen, thanks very much Bill C for an official reference, so glad to have it cleared up. <br />Very much appreciated input thanks everyone!</p>

<p>Thanks for the responses Alan and Glen.<br> Having looked at quite a few data sheets for various films now, it seems that l/mm is the standard. Agfa, Fuji and Kodak all specify resolving power as lines/mm. And looking at old Modern Photography lens tests, their results are given in lines/mm as well, but I have seen results given as lp/mm, and always thought that lp/mm was the standard (one black one white)...<br /><br />Is lp/mm still relevant if it's not used by the film manufacturers? <br />And is l/mm in fact the same unit as lp/mm, or should any data specified as lp/mm be doubled to make it l/mm? Does a white line actually count as a line or just as negative space? <br /><br />Thanks again</p>

<p>Hi, I've been looking through posts and online and was just hoping for clarification on the difference between line pairs and lines per mm. <br />I have read that traditionally resolving power was measured as lp/mm, but the specs on current films (Kodak and Fuji) are given as l/mm. <br> I understand that a line pair is a pair of one light and one dark line, why are they sometimes counted as pairs and sometimes as lines? I read somewhere (but I can't validate the source) that l/mm was actually just counting the dark lines, as to be able to distinguish a dark line there obviously has to be a light line either side. In which case lp/mm and l/mm would be the same number. (i.e. 50 pairs of lines or 50 dark lines). </p> <p>Specs for T-MAX 100<br> 63 lines/mm (TOC 1.6:1)<br> 200 lines/mm (TOC 1000:1)</p> <p>So at 1000:1 is that 100 line pairs/mm ? <br> <br />Thanks I'd appreciate any help clarifying this I am getting more confused the more I read. </p>