View Full Version : Film

31-Oct-2005, 08:56
Anyone read the recent newsletter from defenderphoto.com? The author writes fascinatingly on film and development. I'll try to paraphrase some of it here. He says that 400 speed random grain film does not have more grain than 100 speed film, simply more silver. Therefore that increased grain is primarily due to the use of active developers that dissolve smaller grains thereby leaving only larger grains intact - hence a grainier film.

"Large grain is a product of development action (in a random grain film) whether it's too much agitation, or temperature, or the formula itself - a large grain is always a product of development, not film speed."

His formulated developer uses restrainers and claims to not increase grain size over comparable 100 speed films. This is very interesting to me and I'd like to hear from others on this phenomenon. The PDF newsletter is available through the website.

clay harmon
31-Oct-2005, 09:58
This is nonsense on stilts. There was a discussion on this over on APUG. An ex Eastman Kodak emulsion scientist, along with Bill Troop and others declared this to be complete B.S.

31-Oct-2005, 10:05
What of the claim that traditional film has 'random' grain while T-Grain films have 'constructed' or regular grain?

Donald Qualls
31-Oct-2005, 10:31
"What of the claim that traditional film has 'random' grain while T-Grain films have 'constructed' or regular grain?"

That's reasonable enough, because its at least partly true.

Random grain is what gives modern film much of its latitude -- larger grains are more sensitive, smaller ones less so, so underexposure still produces some density due to development of the larger halide grains. Microfilms have "constructed" grain, though not a tabular type, and are notorious for poor latitude when used in pictorial applications. The "constructed" grain in films like T-Max and Delta, however, is still "constructed" with varying grain sizes, so as to maintain the latitude that is a necessity for common photography.

However, developing only the finer grains makes no sense, because except in the darkest areas, those finer grains are overwhelmed by density created from coarser, more sensitive halide crystals (fine-grain films have a denser coating of the finer halide crystals, so the interstices are smaller); there's simply no way to preferentially develop the finer grains (and won't be until or unless we have nanomechanical developers, tiny machines that can pick and choose where to develop silver and where to leave unreduced halide -- at which point film will lose much of its point because that process will essentially create the image rather than merely developing the image created by the original exposure).

31-Oct-2005, 18:25
Clay, can you direct us to the APUG thread, that forum is a bit mysterious to navigate.
Thanks, Phil.

David A. Goldfarb
31-Oct-2005, 18:30
Probably this thread--

www.apug.org/forums/showthread.php?t=20924 (http://www.apug.org/forums/showthread.php?t=20924)

Jorge Gasteazoro
31-Oct-2005, 18:39
'random' grain while T-Grain films have 'constructed' or regular grain

All films have random grains, IOW the grain distribution is random but is dense enough not to leave patches in the emulsion. The difference is in how the grains are grown. "Normal" film has the silver grain grown under normal conditions. Tabular grain films have grains that are grown under other than normal conditions. I am not an emulsion chemist, but I suspect in this case the put the solution under pressure while the crystals are forming.

clay harmon
1-Nov-2005, 04:59
And, a discussion from the same newsletter;


It is amazing how much people are willing to believe the 'silver quantity versus image quality' myth both for film and for paper. While silver quantity will influence density up to a point, there is a lot more goiing on than just painting it on 'extra thick' to make a really good film or paper. I can prove to anyone who cares about looking at real world data that a film like Tmax400, allegedly one of these awful silver-poor emulsions, can build a higher maximum density than any of these so-called 'old style, silver rich' emulsions such as Berrger 200.

You may hate Kodak and root for the little guy in his garage laboratory, but who do you think has the most PhD's on staff, and has spent the most $$ on research over the years?