Archived posting to the Leica Users Group, 2011/03/19
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Its inherent in the classic Sonnar formula. A lot of lenses made with the Sonnar name, like the 150mm Sonnar that was sold for Hasselblad and for the Rollei SLRs, were not really Sonnar designs. The original Sonnar formula, sold for the old Prewar Contax cameras, had the focus shift but it was accepted because it was one of the first good f1.5 lenses..the price you paid for speed. I think the originals were calibrated to be accurate wide open. The ZM version is basically a modern recreation of the original, complete with its flaws. The flaws are a tradeoff for the lens' high sharpness and unique bokeh. Some people claim that is has a more 3-D rendering. I don't know about that, but I do like the look it gives. -- Chris Crawford Fine Art Photography Fort Wayne, Indiana 260-486-2581 http://www.chriscrawfordphoto.com My portfolio http://blog.chriscrawfordphoto.com My latest work! http://www.facebook.com/pages/Christopher-Crawford/48229272798 Become a fan on Facebook On 3/20/11 2:37 AM, "Nathan Wajsman" <photo at frozenlight.eu> wrote: > Thanks for the explanation, Chris. So basically the lens is systematically > defective--I am surprised that a company like Zeiss would bring such a > product > to market. > > Cheers, > Nathan > > Nathan Wajsman > Alicante, Spain > http://www.frozenlight.eu > http://www.greatpix.eu > http://www.nathanfoto.com > PICTURE OF THE WEEK: http://www.fotocycle.dk/paws > Blog: http://www.fotocycle.dk/blog > > YNWA > > > > > > > > On Mar 20, 2011, at 7:27 AM, Chris Crawford wrote: > >> Nathan and Ted, >> >> The Zeiss ZM 50mm f1.5 C-Sonnar is well known to suffer from a pretty >> severe >> focus shift as you stop down. The point of sharpness moves back as you >> stop >> down. >> >> Zeiss originally sold them with the focus cam set so that focus, as seen >> through your camera's rangefinder, was correct when the lens was set at >> f2.8. At smaller apertures, depth of field was enough that the shift >> didn't >> keep the focused subject from being sharp, but at f1.5 and f2 the lens >> would >> front focus (quite a bit at f1.5). >> >> People complained that the lens wasn't sharp at f1.5, which is untrue. It >> IS >> sharp at f1.5, IF the lens is adjusted to be in focus at f1.5, so later >> ones >> were sold by Zeiss set for f1.5. This makes them unusable at smaller >> apertures till you stop down quite a bit, from what I've seen online. >> >> I know with mine, which is set for f2.8, the lens is not usable at f2 or >> f1.5, which does not bother me as I wanted it for portraits and I never do >> portraits wider than f2.8. Some of the people on rangefinderforum claim >> the >> lens is perfectly fine at f1.5 with one set for 2.8, you just have to >> 'lean >> in' a bit to compensate for the front focusing at wider apertures, but I >> hate guessing-games like that. I need stuff that 'just works' so I use it >> at >> the apertures it 'just works' at. F2.8 and below. >> >> To reiterate, the focus shift is real, despite what some of the >> know-it-alls >> online claim. For some reason some people think it makes them look smart >> to >> claim that focus shift in some lens designs is an 'internet delusion', >> despite Zeiss saying that the C-Sonnar does this, and despite the fact >> that >> testing it is not hard and shows the shift to be there. I have tested my >> lens extensively, and the shift is severe at f1.5 and at f2 its enough to >> make the photo still look too soft. This lens is capable of being VERY >> sharp >> when used correctly. I think mine is sharper in the senter at f2.8 than my >> 50mm tabbed Summicron, though the Summicron is a lot sharper in the >> corners >> at that aperture. Stopped down a couple more stops, they're equally good >> across the full frame. >> >> >> -- >> Chris Crawford >> Fine Art Photography >> Fort Wayne, Indiana >> 260-486-2581 >> >> http://www.chriscrawfordphoto.com My portfolio >> >> http://blog.chriscrawfordphoto.com My latest work! >> >> http://www.facebook.com/pages/Christopher-Crawford/48229272798 >> Become a fan on Facebook >> >> >> >> >> >> On 3/20/11 2:03 AM, "tedgrant at shaw.ca" <tedgrant at shaw.ca> wrote: >> >>> Nathan Wajsman ASKED? >>> Subject: Re: [Leica] New portrait of my son added today >>> >>> >>>> Nice portrait, but how do you know that a particular lens is optimized >>>> for >>>> a particular aperture?<<<< >>> >>> Hi Nathan, >>> You beat me to the very question? :-) >>> >>> Hi Chris, >>> How was this setting established? What kind of measurement method did you >>> use? Or who and how was it determined that f.2.8 was the optimum >>> aperture? >>> >>> Thanks, >>> Dr. ted >>> >>> >>> >>>> On Mar 19, 2011, at 5:28 PM, Chris Crawford wrote: >>>> >>>>> http://tinyurl.com/mack30811 >>>>> >>>>> I shot this one a couple weeks ago with the 50mm C-Sonnar. Mine's >>>>> optimized >>>>> for f2.8, which is the aperture I used. >>>>> >>>>> >>>>> -- >>>>> Chris Crawford >>>>> Fine Art Photography >>>>> Fort Wayne, Indiana >>>>> 260-486-2581 >>>>> >>>>> http://www.chriscrawfordphoto.com My portfolio >>>>> >>>>> http://blog.chriscrawfordphoto.com My latest work! >>>>> >>>>> http://www.facebook.com/pages/Christopher-Crawford/48229272798 >>>>> Become a fan on Facebook >>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> Leica Users Group. >>>>> See http://leica-users.org/mailman/listinfo/lug for more information >>>>> >>>> >>>> >>>> _______________________________________________ >>>> Leica Users Group. >>>> See http://leica-users.org/mailman/listinfo/lug for more information >>> >>> >>> _______________________________________________ >>> Leica Users Group. >>> See http://leica-users.org/mailman/listinfo/lug for more information >> >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information >> > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information