eric_duncan Posted January 29, 2003 Share Posted January 29, 2003 I fell in love with photography as the result of working as a scientist, developing black & white electron micrographs of my work, from an old Hitachi transmission electron microscope. Now my science doesn't take me into the darkroom, but I still enjoy when my two professional interests come together. Searching some scientific papers, I came across some relating to very clever--and very recent-- fundamental silver halide R&D from Kodak. The technology they call "Two-Electron Sensitization" allows films to double their light sensitivity without a loss of grain, by reducing not one but two silver ions per photon striking the film. For over a hundred years, it was one photon, one Ag reduction. Now, suddenly, it's two for one! A fundamental improvement in film technology. And this coming when impressive digital cameras like the DCS 14n are on the scene to lure pros from film. As long as film continues to advance and attract new interest even as digital battles it for market share, photography will be richer for the competition between the technologies. Is anyone aware of Kodak products on the market, or coming soon, which will exploit this new technology? Portra 400UC? It does promise the same fineness of grain as 160VC, but at ISO 400. Could two-electron sensitization be the way this is achieved? Link to comment Share on other sites More sharing options...
kevin_hundsnurscher Posted January 29, 2003 Share Posted January 29, 2003 Looking at the Kodak tech docs, it would appear to be so:<br><br> <table> <tr> <td vAlign="top"> <p><strong>Print Grain Index for�</strong><br> 160NC Film<br> <span style="background-color: #FFFF00">160VC Film</span><br> 400NC Film<br> 400VC Film<br> <span style="background-color: #FFFF00">400UC Film</span><br> 800 Film</p> </td> <td vAlign="bottom" align="middle"> <p>Less than 25<br> <span style="background-color: #FFFF00">28</span><br> 32<br> 36<br> <span style="background-color: #FFFF00">28</span><br> 38</p> </td> <td vAlign="bottom" align="middle"> <p>36<br> <span style="background-color: #FFFF00">40</span><br> 44<br> 48<br> <span style="background-color: #FFFF00">40</span><br> 50</p> </td> <td vAlign="bottom" align="middle"> <p>58<br> <span style="background-color: #FFFF00">62</span><br> 66<br> 70<br> <span style="background-color: #FFFF00">62</span><br> 72</p> </td> </table> Link to comment Share on other sites More sharing options...
jonathan_james Posted January 29, 2003 Share Posted January 29, 2003 This looks extremely promising. The grain of films has steadily reduced over the last 20 years and more. Another major move forward in this direction where so much progress has already been made is very good news indeed. Is there any space for this technology to be used in transparencies? The slow speed of the finest grain slide films continues to be a decided disadvantage to the landscape photographer using a polariser and f16. Link to comment Share on other sites More sharing options...
roger_urban3 Posted January 29, 2003 Share Posted January 29, 2003 I'd be tickled pink to see this technology incorporated into Technical Pan, but hey, that's because much of the time I'm a high resolution addict..... Link to comment Share on other sites More sharing options...
hclim Posted January 29, 2003 Share Posted January 29, 2003 Is there a comparison between the relative sizes of a grain and a CCD/CMOS? Is this relevant/non-relevant? Link to comment Share on other sites More sharing options...
paulrumohr Posted January 29, 2003 Share Posted January 29, 2003 My Kodak rep tells me the new E100G transparency film has a totally new G-rain structure (clever aren't they)? She also told me Kodak just spent 30 million to bring all BW Film production into the legendary Building 38 in Rochester. The emulsions should be very consistent now. Link to comment Share on other sites More sharing options...
struan_gray Posted January 30, 2003 Share Posted January 30, 2003 Eric, can you give a reference for this? It's worth maintaining a little scepticism here. Agfa got a lot of good publicity when it announced that it had made amazinly high speed, low grain films using methyl sensitisers. Lots of cheering from the peanut gallery and online fantasies about new films in the pipeline. But it seems that Agfa have found out what the C19th researchers knew: it's hard to get the methyl derivatives to stay put. Deafening silence allround. Link to comment Share on other sites More sharing options...
struan_gray Posted January 30, 2003 Share Posted January 30, 2003 Oof, not enough coffee yet. I *think* I mean formate, not methyl, but my brain has turned to pink sludge so don't trust even that. Link to comment Share on other sites More sharing options...
pete_andrews Posted January 30, 2003 Share Posted January 30, 2003 So they've found a way to break the laws of quantum mechanics then, have they?<p>I think you've got those figures wrong. The quantum efficiency of latent image production has never been one, or even close.<p>In any case, since development constitutes an amplification process with a factor of several million, a further gain of two seems fairly insignificant. So we get 200 ISO film with grain like 100 ISO, that's hardly the biggest of big deals. Link to comment Share on other sites More sharing options...
jay Posted January 30, 2003 Share Posted January 30, 2003 The only products that've been announced are a motion picture film Vision2/5218 and an intermediate motion picture film. It (5218) was released and announced now, to help keep projects originating on film instead of switching to digital video. I'm sure Kodak will release many photography films with this technology soon -- E100G doesn't have it. And, reducing the grain at a given speed level is an evolutionary step, to be sure, but the quantum efficiency increase is significant because it brings film closer to CCDs which are around 50% efficient. -J Link to comment Share on other sites More sharing options...
struan_gray Posted January 30, 2003 Share Posted January 30, 2003 Pete, the formate doping gave very close to two silver atoms per photon. The formate ion scavenges the electron from the initial excitation, preventing recombination and so increasing the film's sensitivity. The formate molecule dissociates into H2 and a C02 radical, and the de-excitation of the CO2 radical reduces a second Ag atom, boosting the sensitivity still further. All this assumes that the original photon had enough energy, which is why the process is rumoured to be less efficient with red light. It's all laid out with admirable clarity in "Enhanced yield of photoinduced electrons in doped silver halide crystals" by Jacqueline Belloni et al. Nature, 402, 865-867 (1999). I suspect Kodak have found another molecule that does a similar trick without formate's tendency to go wandering about in the emulsion (it only works if it's in or near the halide crystal). It will be interesting to see if they have got round Belloni's/Agfa's patents, or whether they are paying a licencing fee. Link to comment Share on other sites More sharing options...
eric_duncan Posted January 31, 2003 Author Share Posted January 31, 2003 The the fundamental understanding of quantum mechanics is not threatened by this film technology! The way Kodak achieves two silver reductions per incident photon is to incorporate an electron donor into the emulsion, which prevents the dye from becoming oxidized and recombining with an electron which could otherwise reduce a silver. The donor itself generates a stable cation. My reference is J Am Chem Soc., Lenhard et al, 122, 11934 (2000). Kodak have also secured 6 patents relating to two-electron sensitization, and there is a good general review (Dec. 2002) on the R&D page of the Kodak website. Thanks, Struan, for the related reference. As for applications, I for one will certainly take an ISO 400 film which has grain as fine as the best previously available ISO 200 film--considering that grain vs. light sensitivity has steadily improved over the years. A sudden doubling in light sensitivity for a given grain is welcome, to me. As for transparency film, as pointed out the new additions to the Kodak E-family are supposed to benefit from new technology. I have not yet looked into them closely enough to find out the specifics. I plan on buying some, soon. If it's as creamy as Velvia, but at ISO 100, maybe two-electron sensitization is the reason. I plan to find out. Link to comment Share on other sites More sharing options...
eric_duncan Posted January 31, 2003 Author Share Posted January 31, 2003 Sorry, I just noticed Joe's response, stating that E100G does not use two-electron sensitization, answering one of my questions. When a transparency film does, I will welcome it. Link to comment Share on other sites More sharing options...
struan_gray Posted February 1, 2003 Share Posted February 1, 2003 Thanks for the reference Eric. Amazing what Kodak hide away on their website. It looks as if they are pulling the same trick Belloni did, but via the sensitiser molecule rather than the halide crystal. I too see nothing wrong with a reduction in grain. Mopping up the excited electron may also give much better reciprocity characteristics, which would be useful to me if not to the average fashion photographer. Link to comment Share on other sites More sharing options...
pete_andrews Posted February 3, 2003 Share Posted February 3, 2003 That's all very well on a molecular level, but Agx crystals contain many molecules, and the whole process then becomes much more of a lottery.<p>Once the exposure reaches a point where the chances of two or more development sites per crystal are high, then there can be no gain in sensitivity.<p>If you take the simplistic molecular model of one photon of exposure knocking out an electron to immediately give one development site, then it would appear than making the Agx crystals only one molecule big would be the answer to getting higher speed emulsions. That is obviously not the case as seen in practise.<p>It seems that this technique of electron capture does promise to redcuce latent image regression, but I'm not confident that it will actually result in significantly higher practical film speeds in the immediate future. Link to comment Share on other sites More sharing options...
struan_gray Posted February 4, 2003 Share Posted February 4, 2003 The Nature paper I referenced addresses these issues in a fairly non-technical way. Worth reading. Link to comment Share on other sites More sharing options...
martin_bakota Posted February 14, 2003 Share Posted February 14, 2003 An interesting article recently appeared in the Journal of Imaging Science and Technology: Carbonyl platinum clusters as silver halide dopant for photographic latent image formationTreguer M, Remita H, Belloni J, de Keyzer RJOURNAL OF IMAGING SCIENCE AND TECHNOLOGY 46 (3): 193-199 MAY-JUN 2002 Doping silver halide crystals with carbonyl platinum compounds appears to produce an increase in emulsion speed by lowering the rate of electron - hole recombination (i.e. it lowers rate of single Ag atom oxidation back to Ag+ ion). I have done a Science Citation Index search and there seems to be a healthy amount of research into doping silver halide emulsions (with various compounds) in order to make the creation of latent image more efficient. I would not be surprised to see 1 to 3 stop faster films on the market within the next ten yrs. Happy Valentines Link to comment Share on other sites More sharing options...
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