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#11
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In article ,
"Jim Phelps" wrote: Use and GRADED paper to get the 'benefits' of pyro. The light source does not matter so much. DO NOT use VC paper, because it defeats the whole purpose of pyro. This information is completely wrong. Consider the source,...and I don't mean light. Unless your equating light with dimly lit :-) -- LF Website @ http://members.verizon.net/~gregoryblank "To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public."--Theodore Roosevelt, May 7, 1918 |
#12
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In article ,
"Jim Phelps" wrote: Use and GRADED paper to get the 'benefits' of pyro. The light source does not matter so much. DO NOT use VC paper, because it defeats the whole purpose of pyro. This information is completely wrong. Consider the source,...and I don't mean light. Unless your equating light with dimly lit :-) -- LF Website @ http://members.verizon.net/~gregoryblank "To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public."--Theodore Roosevelt, May 7, 1918 |
#13
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"Jim Phelps" wrote in message ...
"Uranium Committee" wrote in message om... The 'benefit' of a stained negative is the stain, which takes the place of silver density for papers that are sensitive only to blue. The stain is yellowish-green, and since these stains block blue light, they are seen as extra density by blue-sensitive paper. Variable contrast paper DOES see 'green', and so the stain DOES NOT act as density for VC papers. Use and GRADED paper to get the 'benefits' of pyro. The light source does not matter so much. DO NOT use VC paper, because it defeats the whole purpose of pyro. This information is completely wrong. No, it's correct! FACT: the stain is yellowish-green FACT: the stain TRANSMITS yellowish-green and STOPS blue light FACT: graded paper is insensitive to green or yellow light FACT: VC paper is sensitive to green light CONCLUSION: the stain ADDS density as far as graded paper is concerned, and DOES NOT add density as far as VC paper is concerned. In addition, the green light that the stain allows through softens the contrast in the most-heavily-exposed areas, precisely the opposite effect that occurs when graded paper is used. Attempting to use VC filtration to raise the contrast simply ignores the stain again, and you end up fighting against the stain. |
#14
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"Jim Phelps" wrote in message ...
"Uranium Committee" wrote in message om... The 'benefit' of a stained negative is the stain, which takes the place of silver density for papers that are sensitive only to blue. The stain is yellowish-green, and since these stains block blue light, they are seen as extra density by blue-sensitive paper. Variable contrast paper DOES see 'green', and so the stain DOES NOT act as density for VC papers. Use and GRADED paper to get the 'benefits' of pyro. The light source does not matter so much. DO NOT use VC paper, because it defeats the whole purpose of pyro. This information is completely wrong. No, it's correct! FACT: the stain is yellowish-green FACT: the stain TRANSMITS yellowish-green and STOPS blue light FACT: graded paper is insensitive to green or yellow light FACT: VC paper is sensitive to green light CONCLUSION: the stain ADDS density as far as graded paper is concerned, and DOES NOT add density as far as VC paper is concerned. In addition, the green light that the stain allows through softens the contrast in the most-heavily-exposed areas, precisely the opposite effect that occurs when graded paper is used. Attempting to use VC filtration to raise the contrast simply ignores the stain again, and you end up fighting against the stain. |
#15
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"Uranium Committee" wrote in message ... "Jim Phelps" wrote in message ... "Uranium Committee" wrote in message om... The 'benefit' of a stained negative is the stain, which takes the place of silver density for papers that are sensitive only to blue. The stain is yellowish-green, and since these stains block blue light, they are seen as extra density by blue-sensitive paper. Variable contrast paper DOES see 'green', and so the stain DOES NOT act as density for VC papers. Use and GRADED paper to get the 'benefits' of pyro. The light source does not matter so much. DO NOT use VC paper, because it defeats the whole purpose of pyro. This information is completely wrong. No, it's correct! FACT: the stain is yellowish-green FACT: the stain TRANSMITS yellowish-green and STOPS blue light FACT: graded paper is insensitive to green or yellow light FACT: VC paper is sensitive to green light CONCLUSION: the stain ADDS density as far as graded paper is concerned, and DOES NOT add density as far as VC paper is concerned. In addition, the green light that the stain allows through softens the contrast in the most-heavily-exposed areas, precisely the opposite effect that occurs when graded paper is used. Attempting to use VC filtration to raise the contrast simply ignores the stain again, and you end up fighting against the stain. It does add density for the blue sensitive component of variable contrast paper but less for the blue and green sensitive layer. This has the effect of modifying the characteristic curve of the paper. It creates what is effecively a shoulder which flattens highlight density. This may or may not be desirable. Some claim to get better prints this way. It probably depends on the subject matter as much as anything else. Essentially, the stain image acts as a mild contrast reducing mask when used with variable contrast paper. When used with graded paper the stain image simply adds to the silver image. This is not an advantage or disadvantage although it makes measuring the effective density of the iamge more difficult since the densitometer must have a filter which matches the spectral response of the printing material. I am not sure about the validity of the idea that the stain image masks grain since it must mimic the grain. Any diffusion of the stain away from the grains where it is generated would affect resolution and sharpness. This is not a common effect of Pyro development. Pyro developers also harden or tan the gelatin in a way which is proportional to the image density. This effect is used to produce relief images for dye transfer and other printing methods. In ordinary negatives it sometimes acts to increase acutance by modifying the diffusion rate at the edges of the image. The hardening itself can cause some increase in acutance because of the bending of light at the edge where the density of the gelatin is different. This differential hardening can also cause minor image distortion. This is of no consequence in normal photography but precludes the use of staining Pyro developers for photgrametry and astrophotography. Pyro is the oldest organic developing agent known. It was first used by F.Scott Archer C.1865 and has been in use ever since. Pyro fell out of use in the 1920's when Metol and Hydroquinone developers were devised. These were more predictable and more stable. Modern Pyro formulas are reasonably predictable but not very stable (PMK seems to be an exception). It is not very well known that Pyro developers also can be used for paper development to obtain warm tones. The stain image is not a dye but rather a very stable pigment, probably longer lived than the silver image. -- --- Richard Knoppow Los Angeles, CA, USA |
#16
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"Uranium Committee" wrote in message ... "Jim Phelps" wrote in message ... "Uranium Committee" wrote in message om... The 'benefit' of a stained negative is the stain, which takes the place of silver density for papers that are sensitive only to blue. The stain is yellowish-green, and since these stains block blue light, they are seen as extra density by blue-sensitive paper. Variable contrast paper DOES see 'green', and so the stain DOES NOT act as density for VC papers. Use and GRADED paper to get the 'benefits' of pyro. The light source does not matter so much. DO NOT use VC paper, because it defeats the whole purpose of pyro. This information is completely wrong. No, it's correct! FACT: the stain is yellowish-green FACT: the stain TRANSMITS yellowish-green and STOPS blue light FACT: graded paper is insensitive to green or yellow light FACT: VC paper is sensitive to green light CONCLUSION: the stain ADDS density as far as graded paper is concerned, and DOES NOT add density as far as VC paper is concerned. In addition, the green light that the stain allows through softens the contrast in the most-heavily-exposed areas, precisely the opposite effect that occurs when graded paper is used. Attempting to use VC filtration to raise the contrast simply ignores the stain again, and you end up fighting against the stain. It does add density for the blue sensitive component of variable contrast paper but less for the blue and green sensitive layer. This has the effect of modifying the characteristic curve of the paper. It creates what is effecively a shoulder which flattens highlight density. This may or may not be desirable. Some claim to get better prints this way. It probably depends on the subject matter as much as anything else. Essentially, the stain image acts as a mild contrast reducing mask when used with variable contrast paper. When used with graded paper the stain image simply adds to the silver image. This is not an advantage or disadvantage although it makes measuring the effective density of the iamge more difficult since the densitometer must have a filter which matches the spectral response of the printing material. I am not sure about the validity of the idea that the stain image masks grain since it must mimic the grain. Any diffusion of the stain away from the grains where it is generated would affect resolution and sharpness. This is not a common effect of Pyro development. Pyro developers also harden or tan the gelatin in a way which is proportional to the image density. This effect is used to produce relief images for dye transfer and other printing methods. In ordinary negatives it sometimes acts to increase acutance by modifying the diffusion rate at the edges of the image. The hardening itself can cause some increase in acutance because of the bending of light at the edge where the density of the gelatin is different. This differential hardening can also cause minor image distortion. This is of no consequence in normal photography but precludes the use of staining Pyro developers for photgrametry and astrophotography. Pyro is the oldest organic developing agent known. It was first used by F.Scott Archer C.1865 and has been in use ever since. Pyro fell out of use in the 1920's when Metol and Hydroquinone developers were devised. These were more predictable and more stable. Modern Pyro formulas are reasonably predictable but not very stable (PMK seems to be an exception). It is not very well known that Pyro developers also can be used for paper development to obtain warm tones. The stain image is not a dye but rather a very stable pigment, probably longer lived than the silver image. -- --- Richard Knoppow Los Angeles, CA, USA |
#17
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Uranium Committee wrote:
Szaboht wrote in message . .. I'm not yet experienced with Pyro development, but I'm considering to give it a try. My questions concern the enlarger lamp for pringing pyro negatives. I read frequently that a cold light head is best for pyro negatives (presumably due to the yellowish stain on the neg), but I have a standard tungsten halogen lamp in my only enlarger, an Omega D2 with Super Chromega color head. I hope to use VC paper (Forte and Kodak). If the spectrum really must be close to that of a cold light head, is there a filtration offset that can be dialled into on the enlarger's color head to closely simulate the spectrum of a cold light lamp? Or, with regard to pringint pyro negs, is the spectral difference between cold light and tungsten halogen too small to be concerned about? Regards, Szabo ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- The 'benefit' of a stained negative is the stain, which takes the place of silver density for papers that are sensitive only to blue. The stain is yellowish-green, and since these stains block blue light, they are seen as extra density by blue-sensitive paper. Variable contrast paper DOES see 'green', and so the stain DOES NOT act as density for VC papers. Use and GRADED paper to get the 'benefits' of pyro. The light source does not matter so much. DO NOT use VC paper, because it defeats the whole purpose of pyro. The stain is without grain and has a nicer gradation of tone than silver has, but again, only for graded (blue-sensitive) paper. A negative correctly developed in pyro has a rather 'thin' silver base which the stain supplements. If the stain were to be removed, the silver density of a properly-developed pyro negative would be seen as too flat and thin. It's supposed to be that way, because the stain assists in providing enough PRINTING density to give a good print. It is not true that VC paper defeats the purpose of pyro. VC paper with blue or magenta filtration makes possible very versatile use of pyro. Magenta filtration in small amounts can intensify the shadows. Pyro makes possible negatives that can have the high contrast required for printing-out papers like platinum and the normal contrast for use with VC papers. |
#18
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Uranium Committee wrote:
"Jim Phelps" wrote in message ... "Uranium Committee" wrote in message .com... The 'benefit' of a stained negative is the stain, which takes the place of silver density for papers that are sensitive only to blue. The stain is yellowish-green, and since these stains block blue light, they are seen as extra density by blue-sensitive paper. Variable contrast paper DOES see 'green', and so the stain DOES NOT act as density for VC papers. Use and GRADED paper to get the 'benefits' of pyro. The light source does not matter so much. DO NOT use VC paper, because it defeats the whole purpose of pyro. This information is completely wrong. No, it's correct! FACT: the stain is yellowish-green FACT: the stain TRANSMITS yellowish-green and STOPS blue light FACT: graded paper is insensitive to green or yellow light FACT: VC paper is sensitive to green light CONCLUSION: the stain ADDS density as far as graded paper is concerned, and DOES NOT add density as far as VC paper is concerned. In addition, the green light that the stain allows through softens the contrast in the most-heavily-exposed areas, precisely the opposite effect that occurs when graded paper is used. Attempting to use VC filtration to raise the contrast simply ignores the stain again, and you end up fighting against the stain. It is quite obvious that you have not tried it, and that you have not reasoned out the answer that you did not try. The yellow stain is a variable density stain. You can bleach out the silver image and leave a yellow IMAGE, not a filter layer. This yellow image can be printed on VC paper by use of sufficient blue filtering. I have done it, and several years ago demonstrated it in an article in Photo Techniques titled "More Pyrotechnics" . Certainly, the yellow image is of quite low contrast when printed on unfiltered VC paper, but it is there. The yellow part of an unbleached pyro negative DOES increase the contrast on VC paper, though not as much as on graded paper. If you do the following experiment, you will see the fallacy in your reasoning. Develop any negative in any non-staining developer to a lower than normal contrast index. Make a straight print without filtration on VC paper. Now bleach the negative in a rehalogenating solution such as is used in sepia toning, and redevelop it in a pyro staining developer. Make a straight print from this negative without filtration. Now make another print using magenta filtration or a #3 or #4 printing filter. Report to us the results if you dare. |
#19
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"PATRICK GAINER" wrote in message ... Uranium Committee wrote: It is quite obvious that you have not tried it, and that you have not reasoned out the answer that you did not try. Pat, I believe you have hit the nail on it's head. He has NEVER tried it and is going on his flawed deductive reasoning. I believe in an older post he said something like "... no I have never used pyro but have seen prints from negatives developed in pyro." Jim |
#20
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"PATRICK GAINER" wrote in message ... Uranium Committee wrote: It is quite obvious that you have not tried it, and that you have not reasoned out the answer that you did not try. Pat, I believe you have hit the nail on it's head. He has NEVER tried it and is going on his flawed deductive reasoning. I believe in an older post he said something like "... no I have never used pyro but have seen prints from negatives developed in pyro." Jim |
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