Archived posting to the Leica Users Group, 2001/02/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]- ----- Original Message ----- From: "Mark Rabiner" <mark@rabiner.cncoffice.com> To: <leica-users@mejac.palo-alto.ca.us> Sent: Friday, February 09, 2001 4:30 AM Subject: Re: [Leica] Re: DOF > Rob Heyman wrote: > > > > It would only be noticeable if the viewing distance did not change. The > > accepted viewing distance for a print is 1.5 times the diagonal. This allows > > the human eye to see the entire image without "scanning". If we apply this > > to an 10x8 the viewing distance is just under 13". To view a 60"x40" from > > the same neg we should stand at around 80". In both cases our eye will see > > the same amount of detail and the same amount of grain. DOF or even > > apparent DOF does not change. > from a practical point of view a normal lens on a 35mm camera is one inch: > so you've got a 30 inch viewing distance ????????????????Mark, I think you have misunderstood. I am referring the the diagonal of the PRINT, not the diagonal of the negative, and it doesn't matter whether we are using a normal lens or a telephoto, to see the entire PRINT comfortably you need to view it from a distance of 1.5 times the diagonal of the PRINT. This means that any fault you cannot see on a 10x8 print viewed from about 13", you will not see on a 60x40 print at 80". Of course if we use larger format there will be differences in grain or quality of the image, but I am talking about different PRINT sizes from the same NEGATIVE. >with a 30x40 > IN 4x5 a 210 is an 8 inch lens which is normal > so your viewing distance from that 7.5 enlargement is 60 inches (8 x 7.5) > seems like you've got twice the viewing distance to witness half of the problem! > > mark rabiner >