Archived posting to the Leica Users Group, 1998/02/09
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> I have heard it said that with the exception of the special purpose films > like Kodachrome 25 - no ASA 200 or more film can resolve (lines/mm) > as much as the average (not special purpose) lens can. > > Does anyone have any hard facts on this? I am speaking of resolution > not contrast or edge sharpness or aberation correction - just ordinary > lines per millimeter. If no facts are available, then opinions will suffice. > > Marvin Moss This is a very difficult question. First some facts from the sheets. 1:1000 contrast 1: 1,6 contrast Fuji Superia 200 125 l/mm 50 l/mm Fuji Superia 100 125 63 Fuji Superia Reala 125 63 Fuji Superia 800 100 50 Fuji Velvia 160 80 Fuji Astia 135 55 Kodak tech Pan 320 125 Agfa APX 25 200 Agfa APX 100 150 Kodak TMax 100 200 63 Kodak Ektar 25 200 These figures in itself are meaningless. If we look at the Velvia these 160l/mm are recorded with a contrast factor of 30%, which is very low. If we go for a 100% contrast (no image degardation) the same film can handle only 40l/mm. The recent add by Zeiss in PopPhoto claims a resolution of 300 l/mm for its MacroPlanar 2,8/60. This claim I find on the high side. Leica lenses easily handle 150 - 250 l/mm (areal resolution!!!!). But that is not the question. Looked at the MTF curves the important figure is the contrast transfer at 80 l/mm. Most lenses have really trouble getting this relatively low value on the film with a good contrast. So here you have it; on the face value most modern films will 'handle' around 125 - 150 l/mm. Most lenses can on one count easily top these figures and chalk up values of 150 and 300 l/m, depending on the measurement method. This comparison gives the plus to lenses. But lenses also are really in trouble to get 80 l/mm. In this comaprison the film easily wins. If you go for high contrast transfer for both system components (film and lens); the film can handle 40 to 80 l/mm and the lens can handle 20 to 40 lines (or to be a bit tolerant 80 l/mm). In this comparison both components are about equal. The best lenses just outperform most films and the best films just outperform most lenses. Are we lucky that with Leica lenses we can have the best of both worlds. Erwin