Archived posting to the Leica Users Group, 2011/03/19
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]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 >