Archived posting to the Leica Users Group, 1998/04/06
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]>inplying that the 10 lp curve may actually be more important. I guess what Dan,Erwin: The 10lpm line in modulation transfer function corresponds to 20 lines per mm in tv terminology. For a 35 mm slide this would translate to 720x480 total high contrast lines. While these are better than the current broadcast standards; they are clearrly inferior to the proposed HDTV standards. Depending on the aperture, a topnotch 35 mm format photographic lens should have a high modulation transfer function from center to edge at 20-40lpm. The Zeiss literature on Hasselblad lenses shows for the 100mm f3.5 Planar T* at f8 an essentialy flat MTF of 90, 80, and 60% at 10,20. and 40 lpm. respectively. Unquestionqbly, it is a spectacular "normal" lens in MF. Consequently, in any high performance lens in the 35mm format, one would like to have at least 60% MTF (without center to edge undulations) at 40lpm. Allowing for the difference in film size, for a projected slide in 35mm to approach Hasselblad qualitity, one would need a MTF of about 80% at 40lpm. I am sure that some Leica lenses meet this severe standard at, say, f5.6. regards, Andrew Jordan