Correct. 'Lines per Millimetre' is the way Kodak described the resolution of their plates. Those we used for high resolution work resolved about 1200 lines per millimetre. The Holographic plates were much better and more expensive. Now that I've thought about this a little our Kern Switars may have done about 450 lpm.
But in ordinary 35mm photographic applications 50-60 lines per millimetre on the film is great ... and good enough for nice big prints; which will not show more than about a tenth of this anyway. But contrast is more important than resolution and without wanting to start a whole new ball rolling, very high resolution pictures with low contrast are terrible. In transmission light microscopy one needs some of each and for that a very carefully adjusted light source, according to 'K�hler's' principle, is required. But for high resolution one needs high resolution film. I think T-Max 100 should resolve about a hundred lpm with care and proper processing. And it has a range of about 8 stops which makes it, and Technical Pan, Kodak's best offerings for B&W photomicrography on 35mm. Don _______________ Dr E D F Williams http://personal.inet.fi/cool/don.williams Author's Web Site and Photo Gallery Updated: July 31, 2003 ----- Original Message ----- From: "John Francis" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, September 15, 2003 8:31 PM Subject: Re: Lens resolution > > > > One black line and one white line is a "PAIR" > > of lines to me. Why would you need 4 lines > > to make up a pair? > > You don't. It's line *pairs* per mm if you count both the black > and the white line. If you only count the black lines (treating > the white as just the background) you get lines per mm. > > In other words: > > 100 line *pairs* per mmm is 100 black lines and 100 white lines. > > 100 lines per mm is 100 black lines (on a white background), or > alternatively 100 white lines (on a black background). > > They all describe the same resolution pattern. The terminology > using line pairs is technically more correct, but the other usage > is widespread and is a closer analogue to the measurements used in > diffraction gratings, which generally talk about rulings per mm. >
