Archived posting to the Leica Users Group, 1997/10/26
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]The first Summicron 90mm was introduced in 1958, the second version (one lens element less than the first version) in 1980 alongside with the 75 Summilux. Leica would be ill advised if they would produce two lenses that competed with each other. So a direct comparison between the two (or three if you add the Elmarit 90) should by definition miss a few points. All three lenses perform quite well when stopped down to f.4.0 or smaller.The differences in flavour or character are most noticable at 1,4 to 2,8. A most important difference between the Summicon 90 and the Summilux 75 is the extremely high center sharpness of the Summicron at f/2,0 against the more even definition of the Summilux at the same aperture (f/2,0). Micro contrast and edge definition of the Summilux is also higher. The Summicron on the other hand has that special creamy definition of very small gradation diferences which produce the subtle hue differences the Summicron is famous for. At f/2,8 the Summicron is on the same level as the Summilux at f/2,0 excepting the extreme corners where the Summicron wins (no feat as the depth of field is greater). At 2,8 the differences are only academic. Here however the Elmarit comes in and scores with superior center definition and a coverage of the rest of the image equal to the Summilux/Summicron brothers. Of course these differences are small and only visible when exacting standards of technique and material are available. At f/2,0 the central definition of the Summicron is a bit lower than that of the Elmarit at 2,8. But the micro contrast and MTF values of the Elmarit (plus less air to air surfaces and therefore less reflections) give it the visual edge. Not well known to most people is the fact that a lens with a higher resolution that the human eye can record actually is worse than a lens with a (lower )resolution and (higer) contrast that is optimalized for certain shooting and viewing circomstances. The fact thet Leica has deceided to produce three different lenses in the 75/90 mm class is proof that they understand quite well that no design can cover all assignments to the most exacting standards. The same goes for the Noctilux. If the often heard argument that the need for a f/1,0 is no longer justified because the emulsion quality has gone up, would be true, any f.2.0 or larger aperture could be dumped. Any ISO400 (colour neg) is almost as good as any ISO100(idem). So instead of using a 1,4 any 2,8 would do also. And the new ISO800 materials are quite good too. So why bother about any diffence at full aperture? Shoot at f/4,0 with ISO800 and a;ll will be fine. Why then is Leica putting all effort in high performance high quality lenses when you culd get the same results with a higher film speed and a lower aperture lens. The answer is of course quite predictable. Such relationships only hold to a certain extent. No one can beat a well exposed and well developed ISO100 b&w negative or colour transparancy film when enlarged 15 to 20 times. Here Leica large aperture lenses are very hard to beat because of resolution, micro contrast and rendition of subtle hues, giving almost a 120 film feeling. Also the fingerprint of a highly corrected 1,4 aperture is totally different from an equally well corrected 4.0 aperture (to stay within the Leica stable). Erwin