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  1. #91

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    Quote Originally Posted by Photo Engineer
    Recent developments in emulsion making have allowed the manufacture of high speed black and white papers using silver chloride emulsions similar to those used in Azo.

    Silver chloride emulsions are not exclusive to Azo paper anymore. Perhaps you should try some Polycontrast IV or other modern paper in amidol.

    PE
    I would be very interested in more information on the manufacture of modern high speed papers using silver chloride emulsions similar to those used in AZO. I assume this is a confirmation of the benefits of silver chloride emulsions as used in AZO?

    BTW, is there a fiber based version of Kodak Polycontrast IV? If not, that paper would be off my list since I don't have any confidence at all in the archival qualities of RC papers.

    And just for the record, though I appreciate the qualities of AZO, I am primarily interested in others forms of hand coated printing processes, such as carbon, kallitype and straight palladium. But I do understand curves, and for my money AZO curves have very distinctive characteristics when compared to other silver gelatin materials.

    Sandy
    Last edited by sanking; 06-04-2005 at 10:01 AM. Click to view previous post history.

  2. #92
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    Mr King, all I know is that recent work with chloride emulsions at Agfa, Fuji and Kodak have enabled them to make a new generation of papers with chloride emulsions. This was done by discovering how to stabilize them, adjust their curve shape, and sensitize them for higher speed. Among other things, doping or epitaxy can be used.

    Another - off track item is that the RA family of color papers has allowed that particular advance in rapid development in color due to chloride or nearly pure chloride emulsions.

    Chloride emulsions are characterized by showing an image with good contrast almost instantly when they contact the developer and then moving up in speed gradually with time. Other types of emulsion show a gradual increase in both speed and contrast.

    I agree with the Azo image tone being exceptional, however the lack of latitude in the upper scale is what strikes me being a particular disadvantage. The lower scale is nothing special when compared to other curves. But you see that the appreciation of a photographic image is largely subjective and it appears that we could argue about it forever. Why argue. Lets just say that we respectfully differ but appreciate the viewpoints that each of us have.

    I don't believe that PCIV is available as a FB paper sadly.

    PE

  3. #93

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    While most seem to express gloom and doom, I think that in 5-10 years the film world will look different, but not be extinct. There aren't as many stables in most cities as there were 100 years ago, but horse related products and services are still available despite the automobile. While most of us don't take ships across the Atlantic due to the impact of the jet airplane, the cruise industry is doing quite well.
    Therefore I think that many of the big players will be gone in a few years, but that they will be replaced by both specialty manufacturers in the western world and by low cost producers in the developing world. We may not be able to get the exact same products that we are accustomed to using, but equivalent products will probably be available by mail order and internet.
    Will it be better then? Doubtfully. Will it be worse? Probably. Will it be different? Definitely!

  4. #94

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    Quote Originally Posted by Photo Engineer

    I agree with the Azo image tone being exceptional, however the lack of latitude in the upper scale is what strikes me being a particular disadvantage. The lower scale is nothing special when compared to other curves. But you see that the appreciation of a photographic image is largely subjective and it appears that we could argue about it forever. Why argue. Lets just say that we respectfully differ but appreciate the viewpoints that each of us have.

    PE
    PE,

    \Actually I though we were already respecfully disagreeing, as opposed ot arguing. If we are in an argument I am at a serious disadvantage because frankly I don't understand your use of the word "latitide," as in "the lack of latitude in the upper scale is what strikes me being a particular disadvantage" in discussing the characteristics of a paper curve. My understanding of the use of this word is either 1) the *allowable *range *of exposures *for *a *given *photographic *emulsion that will still produce acceptable results, or 2) the allowable range of develoment time for a given emulsion. Perhaps you could clarify what you mean.

    Sandy

  5. #95
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    Mr King, latitude can be expressed, as you say, by the allowable range of a photgraphic product. This can be considered either an image statement or a processing statement.

    If you compare the curves in the Kodak URLs I referred to above, you will see that the dmax of Azo is about 1.8 and the Panalure paper I chose to compare it to has a dmax of about 2.2. In terms of imaging latitude (Log E), this is probably about 2 stops. This means that under ideal conditions the Panalure paper will give about 2 stops more effective latitude to an image printed on it than a comparable print on Azo. This translates into more detail in dark and shadowed areas and blacker blacks (or more dense blacks depending on tone).

    Of course, this assumes that the latitude is in the negative in the first place. A negative on a film with short latitude itself will show no appreciable difference and may even look worse on the Panalure, since printing to the same highlights will give dark areas a muddy look on the Panalure.

    I believe that in general, silver chloride emulsions display less variation as a function of development time in a given developer than a chlorobromide. This would mainly be in terms of contrast change vs time. Therefore, the Azo paper might be said to have a high development latitude (ie less change vs time) than a chlorobromide in a common developer. The chlorobromide would change speed and / or contrast as a function of time more readily than the chloride or the doped chloride.

    I hope this helps.

    PE

  6. #96

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    Quote Originally Posted by Photo Engineer
    Mr King, latitude can be expressed, as you say, by the allowable range of a photgraphic product. This can be considered either an image statement or a processing statement.

    If you compare the curves in the Kodak URLs I referred to above, you will see that the dmax of Azo is about 1.8 and the Panalure paper I chose to compare it to has a dmax of about 2.2. In terms of imaging latitude (Log E), this is probably about 2 stops. This means that under ideal conditions the Panalure paper will give about 2 stops more effective latitude to an image printed on it than a comparable print on Azo. This translates into more detail in dark and shadowed areas and blacker blacks (or more dense blacks depending on tone).


    PE
    OK, I now understand what you mean, but I think it might have been more accurate to simply refer to this as a difference of log density reflection readings between the two papers, with the specific developer mentioned.

    But I want to again state that the gold standard for AZO is not development in Dektol but in amidol, and as I mentioned earlier, a Dmax reflection reading of 2.1 is quite feasible with AZO 2 in amidol, and 2.2 or above with AZO 3. You may think I am flogging a dead horse with the repetition but IMO your comparison of curves with AZO and Panalure in Dektol does not give an accurate indication of the true potential of AZO because it is widely known that amidol gives much superior results with this paper.

    Whether the other papers you mention also do better in amidol I don't know. Perhaps someone else might comment on this.


    Sandy
    Last edited by sanking; 06-04-2005 at 09:38 PM. Click to view previous post history.

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