Archived posting to the Leica Users Group, 1998/04/26
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On Fri, 24 Apr 1998, Dan Post wrote: > I hope this doesn't start a flame war, but the recent discussion of > Modulation Transfer Function, aside from the concommitant copyright > discussion has me a bit confused. > In Neblette's book on photography, he holds that the MTF is a 'system' > measurement and includes not just the camera and lens, but the film, and > processing, at the very least. This would mean that for each film/developer > combination, there would be a different MTF chart, even with the same lens > and camera combination. I got the impression that the MTF was of limited use > for judging a camera/lens. It rather gave a generalized idea of the > performance, that taken with other data, the MTF is merely a component of a > method for evaluating optical systems. One can create a MTF chart for just a lens ( use an arial image ) and one can create an MTF chart for film ( use contact printing ). > I could see that if the tester standardized his film and development, say > with Hurter and Driffield's formulas for sensitometric evaluation, and > tested many camera and lens combinations, that you could make judgements for > that 'population' of cameras, at that particular time, and for under that > particular film andeveloper combination. > If one goes on to make prints, then MTF data should include testing the > camera/lens combinations with the particular enlarger lens/paper/development > data... I can understand the concept of multivariant analysis, but it seems > that pretty soon, you end up picking the fly spots out of the pepper, and > really not getting anywhere. > I can tell you that when I started to use a Leica, I had to hustle to get a > lens on my enlarger that could do justice to the negatives. I use Vivitar > VHE lenses- they were the best I could get, and I am sure that if I got a > Leitz lens, I could even see more improvement! > Do they now use lasers for MTF? What is the process today? Is it able to be > standardized so that a lab on one continent can reproduce the results of a > lab elsewhere? Duncan