Archived posting to the Leica Users Group, 2000/03/19
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]The Beals wrote: > LUG'gers, > I can't speak to the original poster's intent, but I understood the > comparison. In fact, it's not a new idea. In an old LHSA Viewfinder > article by Dick Gilcreast, he compares and contrasts the handheld > functionality of a 35mm Summilux to the Noctilux. Mr. Gilcreast suggests, > rightly so, that a camera with a 35mm lens can be shot at lower speed than > the same camera with a 50mm lens. The article suggests that in this > comparison, the available light gathering ability of these lenses are equal > if they are both opened up and shot at their functional handheld speeds (35 > Summilux = 1/15 and Noctilux 1/30). > I would post the URL, but it is since dead after LHSA secured a unique > domain name. > > John Beal II > Redmond, OR John, with all due respect to Mr. Dick Gilcreast, whom I don't know, I dispute the comments he makes, about the light gathering properties of the Noctilux 50 mm f1 lens being the same as the Summilux 35 mm F 1.4 The comment, that at its functional handheld speed, of 1/30 to 1/5 Sec respectively the light gathering is the same. Since the Image of the subject recorded with Noctilux is larger the one recorded with the Summilux, we have to use the lens with the larger focal length as a reference point. (Noctilux) . To bring the image recorded on the film to the same size as the lens with the larger focal length , we have to crop the image of the smaller focal length lens and therefore enlarge it more. This not only enlarges camera shake up to the amount visible by the larger focal length, but due to the greater enlargement required, we loose sharpness and increase grain. If what Mr. Dick Gilcreast said was true, then a 15 mm lens with f4 would have at least the same light gathering properties as the Noctilux. Its handheld speed according to Mr. Dick Gilcreast would be a second or more. We then can go and hope that someone releases a 5 mm lens, with this than we could photograph with 10 seconds or more while walking along. There is no way, of comparing lenses with differing focal length values with regards to speed or camera shake or light gathering properties. A f1 lens will always gather more light then one with a smaller opening. Regards, Horst Schmidt