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keithwms
12-22-2009, 11:24 PM
Ray, I would say that the published to unpublished ratio of work at EK is on the order of 1:100. That means that a lot of work is never revealed.

I think this is true of all major research-based corporations and many gov't funded projects. If you are working on something small, it gets published. If you are working on something big, it doesn't get published. At least not for many years.

NDAs are the bane of my existence. Well, those and MTAs (materials transfer agreements) which can be even worse.

Photo Engineer
12-23-2009, 08:38 AM
Thanks all for the clarifications.

Given what Mitchell said, I believe it was due to the fact that he was not given a lot of information by EK researchers for one reason or another. I know that George Byrd was given all of the facts available though and I met with him several times with specific orders to disclose all! I'm not sure, but I believe that Byrd was with Princeton at the time.

PE

wildbillbugman
12-23-2009, 10:43 AM
Those were probably made with an Ammonia digest and would be considered rounded cubes or rounded octahedra.

PE

RE,
Will the use of high levals of Br in relation to Ag also serve to round corners?I mean all of the Br in the batch prior to any Ag adition.
Bill

wildbillbugman
12-23-2009, 11:10 AM
Another question about rounded corners:
Will speed and duration of mixing serve to round the corners? Reduce crystal size? Perhaps the relatively low shear of a magnetic stirring bar would do niether?
Bill

Photo Engineer
12-23-2009, 12:52 PM
Bill;

High bromide will not help form cubes to allow rounding of corners, but if you add a lot of bromide after the cubes are made, then you have created the conditions that there may be some rounding due to solvency effects during digestion.

Speed and duration of mixing may or may not influence this effect. Generally, IMHO, it does not. Neither does addition rate. Addition rate affects size and grain size distribution. Of course, slow mixing will tend to create a greater mix of crystal types or even an unusable emulsion. I have done that with some makes with poor mixing at small volumes of starting materials.

PE

keithwms
12-23-2009, 04:57 PM
Given what Mitchell said, I believe it was due to the fact that he was not given a lot of information by EK researchers for one reason or another.

That could be it. My understanding was that Jack had some results for new ways to sensitize that EK didn't want to invest, and ther was a particular person at EK with whom he had a falling-out over this. So Jack went to Fuji. Of course, higherups at EK and Fuji must have known already that the heydays for research on silver halide sensitivity were over. As you have noted elsewhere, there is a *lot* of fantastic research on the shelves that may never go to market.

Anyway, like I said, I know nothing of emulsion science. I would just guess that a crystal with well defined electron and hole migration paths would be advantageous. The surface mobilities of the electrons and holes on the crystal must be very important. If the particle is faceted then I guess there will be sensitization hotspots, and I imagine the sensitizers adsorbing preferentially in a number of clusters related to the number of facets (or perhaps facet boundaries).

Photo Engineer
12-23-2009, 05:29 PM
You left out "twinning". :D

We have investigated just about everything you can imagine. Think about this... Maybe we had already done what Mitchell was proposing and either found it a dead end or were using it as a trade secret. In either case, we would not divulge anything about it. In fact, his going to Fuji in either case would have been an advantage to EK and we would probably have let him, if he ever threatened anyone that he would do it.

PE

Ray Rogers
12-23-2009, 07:58 PM
You left out "twinning". :D

His going to Fuji... would have been an advantage to EK....

PE

That was an erie smile... (PE) and a critical omission (Keith),
since that is exactly where this research was put to use!

How did Kodak benefit by Mitchell's ideas being used by a competitor? !!

Photo Engineer
12-23-2009, 08:12 PM
Ray;

I think you will find that Kodak used twinning as well. In any case, thin t-grains were a Kodak invention and a Fuji invention at the same time, then Fuji, IIRC, moved towards thicker t-grains. IDK the exact sequence, but this was a fast moving field. And, Anabelle was working on 2 electron sensitization while Paul was working on dye layering.

These latter two allowed Kodak to surpass anything anyone else was doing. It gave them at least 1 - 2 stops in speed with the same size grain (each method) and when combined it gave 2 - 3 stops. This has given them a commanding lead in Motion Picture films, just when no one needs it. :( And, you see, we are back to the original question - ie. what might we have seen in the absence of digital?

PE

Ray Rogers
12-23-2009, 09:30 PM
Ray;

I think you will find that Kodak used twinning as well. In any case, thin t-grains were a Kodak invention and a Fuji invention at the same time, then Fuji, IIRC, moved towards thicker t-grains. IDK the exact sequence, but this was a fast moving field. And, Anabelle was working on 2 electron sensitization while Paul was working on dye layering.

These latter two allowed Kodak to surpass anything anyone else was doing. It gave them at least 1 - 2 stops in speed with the same size grain (each method) and when combined it gave 2 - 3 stops. This has given them a commanding lead in Motion Picture films, just when no one needs it. :( And, you see, we are back to the original question - ie. what might we have seen in the absence of digital,

PE

Yes, quite right. The nursing and pampering of tabular grains was a Kodak moment even though technically, the tabular grains themselves were not really invented, but had been formed inadvertenly many years earlier. (I would say that it was actually the emulsions that used tabular grains that was invented but anyway, getting back to the thread...)

I think the issue here was latent image dispersion and how to concentrate the electrons in, to use Keith's words, an optimum "hot spot".

I have not really looked at the work directly, so I am only guessing :) but if Anabelle and team was looking at Mitchell's work at the same time as they were working on 2 electron sensitzation, well, likely they would have been less impressed, but I think you are correct and we do come back to where we would be today (and tomorrow!), in the absence of digital.

wildbillbugman
12-23-2009, 09:50 PM
Perhaps ther will be a giant Solar Flair and all the digital cameras on earth will be ruined. Then there will be a cripling shortage of bateries and digital cameras will be gone. Or even a nuclear explosion 400 miles above the earth.............................
Pleasant Dreams,
Bill

wildbillbugman
12-23-2009, 09:57 PM
[ Of course, slow mixing will tend to create a greater mix of crystal types or even an unusable emulsion.

PE[/QUOTE]

PE,
Could you specify what about the emulsion made it "unusable"?
Bill

keithwms
12-23-2009, 09:57 PM
The research will not be "lost".... it may not show up in a consumer film, but rest assured that there are plenty of folks very interested in the underlying photophysics.

Photo Engineer
12-23-2009, 10:01 PM
Well, IDK when Mitchell's work took place, but Anabelle's work took place nearly 20 years ago. This is not untypical of Research, Development and Product release cycles. If you reconcile those dates, maybe Anabelle preceded Mitchell but I know it was unpublished.

PE

wildbillbugman
12-23-2009, 10:04 PM
The research will not be "lost".... it may not show up in a consumer film, but rest assured that there are plenty of folks very interested in the underlying photophysics.

Keith,:D

That is the best news I have heared today. Perhaps there is room for "optimists" on this planet.
Bill

Photo Engineer
12-23-2009, 10:05 PM
[ Of course, slow mixing will tend to create a greater mix of crystal types or even an unusable emulsion.

PE

PE,
Could you specify what about the emulsion made it "unusable"?
Bill[/QUOTE]

The above quotes are a bit garbled due to parsing, but....

Bad mixing will cause local hot spots which lead to something akin to pepper grain which is actually huge crystals that cannot be peptized by gelatin. This is known in the literature so I'm sorry that I didn't go into detail as I thought that it was known.

In any event, the emulsion has huge crystals that can be felt with the finger and are "crunchy". They give rise to lower contrast and big black blotches in the image.

PE

wildbillbugman
12-24-2009, 01:55 PM
Yes PE,
Thank you for the clarification. I have seen this GRIT in some of my own emulsions. I have tried to filter out the grit with multiple gold mesh filtrations. But the subsequent emulsion still "sucked". I think that I will switch from magnetic stirring plates to overhead mixers, with hot-plate heated water baths under the emulsion. Buying used magnetic stirrers on Ebay is a real crapshoot. They often just do not have enough torque.
Bill

Photo Engineer
12-24-2009, 02:25 PM
Bill;

In the range from 100 - 500 ml of emulsion, 300 RPM or higher (without stirring in bubbles) with a magnetic stirrer should work. If it does not, then the formula is off.

PE