Archived posting to the Leica Users Group, 1998/01/28
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]After reading all of the following, are Marc & I vindicated? or are we in even more trouble? Erwin... HELP! Even more confused, Jim ############# 4 ################# At 10:15 AM 1/29/98 -0500, Ken wrote: >I realize that this thread is mostly about wide angles, but Leitz made a >very good explanation of why curvature is not a problem and in fact may be >usefull in their explanation of the 400 f6.8 Telyt when it was introduced. > >They explained that the edges actually focus closer than the center, thus >allowing the foreground of a picture to be in focus when it may not have >been if the field were flatter. I have found this to be useful when using >this lens. > >I haven't applied this to wide angles, but I don't see why it could not be >exploited for these lenses also. > >kw > ############# 3 ################## >>I will politely suggest that I think both Jim and Marc and many others >>are holding to a widely held concept of field of curvature that is a >>bunch of bunk. My understanding of field of curvature is that is the >>primary cause of why resolution drops off sharply or not so sharply in >>the corners when a lens is wide open. Stopping down the lens improves >>resolution in the corners because it is correcting that curvature. A >>lens with a high field of curvature will do a poor job at rendering >>flat objects unless stopped down, it will also do a poor job of >>rendering objects in 3-d since many of the individual objects you are >>photographing are relatively flat but at different distances. It's >>depth of field that allows us to shoot 3-D subjects with sharpness, NOT >>CURVATURE OF FIELD! A lens with high curvature of field will >>certainly not improve sharpness at near distances in the corners and at >>infinity in the center. >> >>Duane Birkey >> ########### 1 #################### >>>>>Fortunately, from my perspective, the newer Leica lenses seem to be >>>>addressing >>>>>the curvature of field issue. >>>> >>>>There are folks who LIKE wide-angle lenses to have marked curvature >>of >>>>field due to the nature of wide-angle photography: quite often, the >>>>picture has close-in sides and far-away centers, so curvature allows >>a >>>>picture crisp and sharp from corner to corner. >>>> >>>>Marc >>>> >> ########## 2 ######################### >>>I, for one, subscribe to this (what Marc just described). So what do >>other >>>people use wide angle lenses for? >> >>>Jim >>