I believe that the assertion that if a print is viewed from far enough away, resolution doesn't matter is commonly used to oversimplify or simply dodge thinking about print requirements. Further, who has the right to someone else what the correct viewing distance is to his own prints?! Taking the argument to the extreme, if you stand a mile from a print, the print resolution will indeed not matter.
Originally Posted by pen s
Its simple to quantify print resolution requirements, just using geometry. This is a simple experiment I have done: print a pattern of line pairs/mm up on a sheet of paper, alongside a smooth grey tone, and walk away from it. At the point the texture of the line pairs disappears, the two pictures will start to appear the same. Measure this distance. From here you can calculate the given number of line pairs a print requires for a given viewing distance, for you. You might pick a pattern with a frequency of 1.0 lp/mm. If the viewing distance at which this appears to become a smooth tone without texture is 4m, and one views prints at 50cm, then you have a print resolution requirement of 8lp/mm.
Yeah, and the additional irony is that I also use a Bronica ETRSi!
Originally Posted by wblynch
I mention print sizes as I think they are easier to interpret than raw lp/mm on the negative. When I shoot a batch test of lenses, I am in fact just calculating the resolution they are capable of laying down on a negative (this is a convolution of developer, agitation, tripod, focus accuracy etc etc). Its important to shoot a batch as then the relative performance can be seen easily and as resolution testing is a bit subjective in that the limit of the resolution is determined by the definition of acceptable minimum visible resolution. This is inherently dependent on the operator, or "nut behind the camera". By doing several lenses at once, it ensures some consistency though, and I can end up with a relative measurement. Whole thing takes about half an hour, I note it down in a book where I have previous results, and when I get a spare minute once the film is developed, check it out under the enlarger using a 25x scope and good enlarging lens.
I think the first thing I need to do is retest the lens, with a F Zuiko 50/1.8 and a Zuiko MC Japan 50/1.8 for comparison. Will post back in case anyone ends up reading this thread and finding it vaguely interesting to know the difference between the various incarnations of the slower Zuiko 50's.