I assume you are talking about Kodak Publication #5 "Kodak Professional Black-and-White Films", it is definitely a definitive work. The publication went through many upgrades with the edition released in the 80's and 90's. Although I prefer the early #2 edition, there were improvements and modernization in the information over the earlier editions of the 60's and 70's. Also the price jumped from below $3 to $10.95 "The Graphic representation of a typical photographic tone reproduction" among other diagrams really clarifies the relationship between scene, lens, film, and print. Some factors that are harmful to photographic reproduction become apparent with gross negative overexposure, they can difficult to print because of the high density levels, also graininess increases, and sharpness decreases. Kodak stated "three stops of over exposure should be considered the practical limit". In the later editions Kodak deleted this statement. I think what is wonderful about Black and white photography is the fact that one can exploit the possibilities of the extreme latitude in exposure, the wide range of films, development possibilities, choice of papers, the possibility of manipulation during printing, and post treatments to produce some really great images, or some real dogs. Who knows some dogs are mans best friend. Jonathan Ayers [mail1@xxxxxxxxxxxxxxxxx] -----Original Message----- From: pure-silver-bounce@xxxxxxxxxxxxx [mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Richard Knoppow Sent: Saturday, March 22, 2008 4:29 PM To: pure-silver@xxxxxxxxxxxxx Subject: [pure-silver] Re: Kodak vs Ilford ----- Original Message ----- From: "mail1" <mail1@xxxxxxxxxxxxxxxxx> To: <pure-silver@xxxxxxxxxxxxx> Sent: Friday, March 21, 2008 10:26 PM Subject: [pure-silver] Re: Kodak vs Ilford > Richard, Your comments on film curves verses film types is > excellent. > > Thank you:-) I didn't talk about the shoulder because most modern films don't really have a shoulder until they reach impractical densities. Most B&W films have an enormous overexposure latitude, six to 10 stops in many cases. This is not the _range_ of the film but the amount the exposure can be increased from the ISO exposure and still have good tone rendition. I suppose I should define a shoulder. Just as the film has a low contrast area for very low exposures (the toe) it also looses contrast for very high exposures. At some point the film reaches its maximum density and will just go no further. The theory books will show an area of reversal for extremely high exposures but modern films do not seem to ever reach this point. As the highest densities are reached the contrast is reduced and this part of the curve is called the shoulder. A shoulder can also be produced by the developer. Some developers just are not active enough to develop the highest possible densities on the film. If you look at the data sheets for Kodak films which show development in the Versamat automatic processor you will find the higher densities shoulder off at noticably lower densities than when developed in something like T-Max or even D-76. It is possible to generate an artificial shoulder by using what is called a "compensating" developer. These are highly diluted or otherwise designed to have too low an activity to reach the highest densities. Also, development without agitation will result in local exhaustion. In the dense areas the developer reaction products build up slowing down development. In normal processing the agitation removes these reaction products and allows fresh developer to penetrate the emulsion. Not all developers are equally sucessful in stagnant development because some reaction products actually accelerate development rather than restraining it. A developer containing Metol as the sole development agent will exhibit compensation and also edge effects because the reaction products of Metol are restrainers. Rodinal, which is related to Metol behaves the same way. The reaction products of hydroquinone, OTOH, are accelerators and a hydroquinone developer will not show the same sort of effects from low agitation as one having only metol in it. Printing negatives with very high density highlights is a problem. If the image is not too complex the exposure of different areas can be adjusted by burning and dodging. To do this well (so that its not obvious on the final image) is not too easy and requires a lot of practice. Local contrast can also be reduced by the use of contrast masks. These can be made with a contrast higher than the negative so that they result in a non-linear final curve. Contrast masks used to be common in color printing especially with Cibachrome. They are not too difficult to do for B&W. Similar effects can be gotten from electronic image editing programs like Photoshop but many are not aware that they can be generated photographically albeit with more work. A last word on film curves: I think the best explanation of their effect is in the older Kodak film databooks. I have no idea where to find these other than camera swap meets or dealers specializing in this kind of thing. Its possible some library systems may have them. The edition is not important because the same text was reprinted with the film data sheets tipped in. Its the text you want so having obsolete data sheets is of no consequence. --- Richard Knoppow Los Angeles, CA, USA dickburk@xxxxxxxxxxxxx ============================================================================ ================================= To unsubscribe from this list, go to www.freelists.org and logon to your account (the same e-mail address and password you set-up when you subscribed,) and unsubscribe from there. No virus found in this incoming message. Checked by AVG. Version: 7.5.519 / Virus Database: 269.21.8/1338 - Release Date: 3/21/2008 5:52 PM No virus found in this outgoing message. Checked by AVG. 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