Archived posting to the Leica Users Group, 2007/01/11
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On Jan 11, 2007, at 8:51 PM, Henning Wulff wrote: >> On Jan 11, 2007, at 6:23 PM, Len wrote: >> >>> Thanks. I have the use of it (Telyt 560/f6.8) for the weekend along >>> with a R8 body. I >>> still find it hard to believe a simple 2 element lens can be that >>> good. >> >> I have a friend, a professor of optical physics, at the University of >> Rochester who insists that the sharpest long focal lenses have the >> fewest elements. The Telyt lens only covers a field of 3.5 degrees on >> a 35mm frame, 4.5 degrees on an M8 frame. > > Hi Larry, > > I think you might have the two angles mixed. :-) > > But it is a very good lens. Due to this, the 560 is actually somewhat > better, or rather of more even performance than the 400. > > The sharpest long focus lenses would be those of limited elements, > such as the 3 element 800/6.3 that used the most appropriate glasses. > The 400 and 560/6.8 Telyts used special, newly developed glasses, but > not that exotic in today's terms. The 800 unfortunately was pretty > much unaffordable. It certainly had better performance than the even > much more expensive and also very complicated 1200/5.6 Canon EF. > >> With that narrow a field you don't need to worry about all the >> aberrations that multiple elements are required to correct. In fact, >> if you used a narrow band pass filter, a single element lens would be >> almost ideal. > > A bit tough on colour photography, which the narrow angle achromat is > very good at otherwise. > Leica seems to be continuing the 'fewer elements' design philosophy. Comparing Nikon and Canon 300mm f/4 lenses with the 280 f/4 APO the APO-Telyt has the fewest elements - and the highest performance. Doug Herr Birdman of Sacramento http://www.wildlightphoto.com