Archived posting to the Leica Users Group, 1999/05/10
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Actually- all film has silver and is in a sense, B&W. What they have attached to the silver halide is a dye complex. C-41 and E-6 processes use developers that have the ability to 'couple' the colorless dye into a colored analine type, insoluble dye. The silver being fixed, bleached and washed out. These silver halide/dye complex molecules are really large, and there is a need for a relatively thick emulsion, or at least in the older films, before tabulature type grain ( T-grain technology). Kodachrome has/had the dye substrate attached to the silver halide, but the couplers were not in the emulsion but added by a diffusion process when the film was developed. It was a long and costly process in days of yore, requiring a full time chemist to monitor everything. Since the couplers were not in the emulsion, it was thinner and the molecules of Silver halide and dye were smaller and closer together- smaller apparent grain. I have no doubt that with the advent of T-grain films, especially slide films, will see thinner emulsions and smaller apparent grain rivalling Kodachrome. It's just a matter of time. Interestingly enough, the developing agent in Rodinol, paraminophenol, is a 'coupling' developer. When you do Tri-X, the blue color in the spent developer is the yellow light absorbing dye that has been coupled and washed from the film- p-aminophenol couples to anilone dyes and they are water soluble! Try developing an exposed strip of, say Fujicolor, in Rodinal, then wash the film in a tray- they dye image gradually washes away! (Over expose it so the images doesn't wAsh out in the stop and fix bath!) Dan - -----Original Message----- From: Jim Brick <jimbrick@photoaccess.com> To: leica-users@mejac.palo-alto.ca.us <leica-users@mejac.palo-alto.ca.us> Date: Monday, May 10, 1999 5:28 PM Subject: [Leica] RE: Kodachrome Valley >If my feeble 5th sense serves me correctly... > >The last time I checked, Kodachrome was still a B&W film, with real silver >grain, and the color added in the processing. The result is a film with >"real" silver grain. > >Provia is an E6 film, where the color is within the film emulsion. >Processing completely strips away all silver, it having been replaced with >color globules. > >So in reality, Kodachrome will have grain and Provia will have globs. I'm >not sure that they can be scientifically compared. > >Jim GO5 Brick > >>DonjR43198@aol.com wrote: >> >>Has anyone had an opportunity to test the new Fuji Provia Pro RDP III? It >>was reported to have even smaller grain than Kodachrome 25. > >At 04:39 PM 5/10/99 -0400, Alistair wrote: >>Here we go again, I'll try and save us all some time and effort. >> >>Well if the grain's not small enough it's probably because the troglodyte >>gnome who polishes the Kodachrome grain got sick recently and his >>replacement was not up to snuff. >> >>Big Yellow will therefore go bankrupt. >> >>Next. >> >