On Apr 20, 23:53, John Allain wrote: [ Pete wrote ] under Good question. I can't find any actual figures on Kodak's website. The figure I used is one I saw in a couple of places on the web, and in some old notes (see LP Clerc, Photography: Theory & Practice, sec.349). I used to be really into photography, and about 30 years ago, and I did a 3-year HND course which included a lot of theory. I've seen references to about 1/10th or even 1/20th of that in various places, too. That seems too low, but there could be several reasons for that. Firstly, it used to be the case that only Kodak would process Kodachrome -- one of the reasons professionals used to use it only for special purposes, preferring Ektachrome because it could be processed locally (and therefore quicker, and with "adjustments"). That's no longer the case, but I don't know if Kodak have changed the process (quite likely) or just made it available to other processors. I do know that professionals could get a different service from Kodak than normal users (because I could, via the college I studied at) and that could make a big difference to the results. We used to reckon a 35mm Kodachrome slide roughly comparable to a 6x6cm Ektachrome. Not that Ektachrome's at all poor: want a good colour print? Take an Ektachrome slide and make a Cibachrome print. Except I don't think you can get Cibachrome any more. The low figures I've seen for Kodachrome have been on pages where it's compared to other colour films, and I think they're suspect, because I don't think they're the result of optimal (or even close) conditions. I'd be prepared to believe that 2000 lines/mm is a theoretical figure based on grain size. If so, that won't be the true figure for a real exposure in a real camera, so I'd take it with a pinch of salt. A "good" lens on a 35mm camera typically has a resolving power no better than 150-200 lines/mm (ref LP Clerc again, and MJ Langford, Advanced Photography). -- Pete Peter Turnbull Network Manager University of York