Noctilux/Summilux/Summicron Comparison <p> Several weeks ago, I posted the results of a comparison I had done between a Noctilux and a Summicron, and mentioned I wished I had had a Summilux to test at the same time Last week I came across an opportunity on a Summilux and took it. So, for those who are interested, I re-shot the test targets, this time with all three lenses, and offer the results below. The lenses I compared were a fifth version Summicron, which is the last tabbed model with the removable/reversible hood; a current version Summilux, with the built-in lens hood; and a second version Noctilux (Canadian), with the removable hood. The same M6 TTL body was used for all shots, the camera was mounted on a tripod, and the film used was Velvia. Note: The new results for the Noctilux and the Summicron did not vary significantly from the prior comparison, but having the Summilux in the mix required me paying more attention to the subtleties of the differences. Again, these are nothing more than my impressions, and I share them for those who have an interest in this type of discussion. <p> At f1, I rate the sharpness of the Noctilux as "Good" at the center and edges. There is noticeable vignetting of about 2 stops at the extreme corners at f1. <p> At 1.4, the Noctilux center sharpness moves up to "Very Good", while the edges remain "Good". Interestingly, the performance of the Summilux is essentially the same as the Noctilux at this aperture. The vignetting on the Noctilux has been greatly reduced, but is still visible, and is a bit more than that on the Summilux. <p> At f2, the Noctilux and the Summilux remain equal in the center at "VG", and are almost as good as the Summicron which I rate as "VG+". The Summicron is "VG" at the edges, and better than the Summilux which has moved up to "G+" and the Noctilux which remains a "G". There is a slight, and virtually identical amount of vignetting visible in all three lenses. <p> At f2.8, the Noctilux now gets a "VG" for center and edge sharpness. The Summilux and Summicron are essentially equal in the center and have moved up to an "Excellent". The Summilux now gets a "VG" at the edge, but the Summicron has improved as well, and getting an "E", and the Summicron now exhibits its trademark of uniform sharpness corner to corner. There is a trace of vignetting visible in the extreme corners of the Noctilux and the Summicron, but interestingly none was detected in the Summilux. <p> At f4 the lenses continue their performance and all get the same ratings as for f2.8 above. No vignetting was noticed in any of the designs. <p> At f5.6, the Summicron and the Summilux are still "E" in the center, and the Summilux has gained a bit at the edges and is almost, but still not quite equal to the Summicron. The Noctilux has lost a little ground, but is still "VG" at the center and edges. <p> At f8, the smaller aperture has begun to take its toll on the designs, but for some reason to a slightly lesser degree on the Noctilux, so that in essence, all three lenses now rate a "VG" at the center and the edge. <p> At f11, and f16, the smaller apertures continue taking their toll on all three designs, and for all practical purposes, the three lenses perform at essentially the same level, rating "VGs" at the center and edges. <p> Both the Summicron and Summilux are Leica-neutral in colorcast. The Noctilux, on the other hand, runs slightly to the yellow-warm. I learned recently that Leica uses a special UV glass in the Noctilux because its refractive index was ideal for the lens computation, and could also explain the warmer cast. <p> While bokeh on the Summicron is very smooth and pleasing, I found it even (slightly) more so on the Summilux. On the Noctilux, the bokeh has an almost "liquid" smoothness to it that I think imparts that special "look" the Noctilux is known for. <p> So, which one is the best? Tough question. All of these lenses perform at a very high level, and all have their specific strengths. The Summicron is the sharpest corner-to-corner at most working apertures, the Noctilux excels in low light (and high contrast light), and the Summilux is somewhat of a well-sized compromise between the two. For my style of shooting I could probably make a good case for choosing any one of the three. In fact, based on the results of my earlier test comparing the Noctilux and the Summicron, I made a case for keeping both. However, when push came to shove, I almost always grabbed the Summicron over the Noctilux to round out my shooting bag because of its compact size. The only problem was, more than once I found myself looking for an extra stop on the Summicron that wasnt there. So, Ive decided to go with the compromise. Im giving up the corner-to-corner sharpness of the Summicron and the extra stop and "look" of the Noctilux in the interests of having maximum versatility and keeping the weight and complexity - not to mention cost - of my M system to a minimum by choosing one lens - the Summilux.