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#1
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Agfa MCP RC paper contrast
"sreenath" wrote in message ... Hi, I have been using this paper (11X14) with Ilford filters. I don't know if I am sufficiently developing films, but prints have low contract. Do Ilford filters allow all possible contract with this paper? For example, does Ilford Grade 4 filter really give grade 4 results with Agfa paper? thanks, Sreenath Is this genuine old stock AGFA paper? If it is the paper has probably lost some contrast. If its some current clone then the manufacturer should be contacted about what filters to use. Sometimes, if there is a chart for setting a color head you can tell whether the paper is designed for Kodak or Ilford filters. The two are not the same. While one can be used for the other paper the grade steps and the exposure compensation will not be the same. If you have access to a step wedge and reflection densitometer you can measure the contrast. Otherwise its guesswork. Even without the densitometer you can get a pretty good idea of the contrast visually since the step wedge has more steps than the paper will reproduce. Stauffer makes good step wedges, the uncalibrated ones are not very expensive. Actually a Kodak Projection Print Scale, while not at all a precision device, can give you a good idea of contrast via visual measurement. Note the developer can make a little difference. Try Dektol at 1:1 rather than 1:2 or the equivalent with another developer to see if it makes any difference. Testing with known negatives will also help since you will then isolate the problem to the paper and not the negatives. My experience with AGFA paper when it was still in production by AGFA was that it worked with both Kodak and Ilford filters although I mostly used Kodak ones. It was one of my favorite papers and I never had problems with lack of contrast or poor blacks. Current stuff may or may not be the same regardless of the name on it. -- Richard Knoppow Los Angeles WB6KBL |
#2
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Agfa MCP RC paper contrast
"sreenath" wrote in message ... On Dec 11, 7:40 am, "Richard Knoppow" wrote: "sreenath" wrote in message ... Hi, I have been using this paper (11X14) with Ilford filters. I don't know if I am sufficiently developing films, but prints have low contract. Do Ilford filters allow all possible contract with this paper? For example, does Ilford Grade 4 filter really give grade 4 results with Agfa paper? thanks, Sreenath Is this genuine old stock AGFA paper? If it is the paper has probably lost some contrast. If its some current clone then the manufacturer should be contacted about what filters to use. Sometimes, if there is a chart for setting a color head you can tell whether the paper is designed for Kodak or Ilford filters. The two are not the same. While one can be used for the other paper the grade steps and the exposure compensation will not be the same. If you have access to a step wedge and reflection densitometer you can measure the contrast. Otherwise its guesswork. Even without the densitometer you can get a pretty good idea of the contrast visually since the step wedge has more steps than the paper will reproduce. Stauffer makes good step wedges, the uncalibrated ones are not very expensive. Actually a Kodak Projection Print Scale, while not at all a precision device, can give you a good idea of contrast via visual measurement. Note the developer can make a little difference. Try Dektol at 1:1 rather than 1:2 or the equivalent with another developer to see if it makes any difference. Testing with known negatives will also help since you will then isolate the problem to the paper and not the negatives. My experience with AGFA paper when it was still in production by AGFA was that it worked with both Kodak and Ilford filters although I mostly used Kodak ones. It was one of my favorite papers and I never had problems with lack of contrast or poor blacks. Current stuff may or may not be the same regardless of the name on it. -- Richard Knoppow Los Angeles WB6KBL Hi, The paper came in plain unmarked box, but I think this is the original Agfa paper, bought on eBay a few years ago. I bought 250 sheets of 11X14 and like the paper very much. Since I don't have access to step wedge or densitometers, I cant really check the negatives. The problem is also compounded by the fact that developers are no longer available commercially in India. I mix my own and its activity is also a suspect. How much contrast does paper lose over time? I will try a stronger print developer (I use ID-62 at 1+3 which is the recommended dilution) thanks for the help, Sreenath The loss of contrast varies a lot among papers. Variable contrast papers do not seen to have as long a shelf life as graded ones. I found that old Kodak VC paper lost contrast faster than either AGFA or Ilford but, unless the paper has been stored frozen, its going to suffer chemical changes that will lower its contrast and make it foggy. You may be able to get some idea of the contrast by making stepped exposures, the same as you would for testing for correct exposure. You can get the equivalent of a step wedge using this method but the step wedge eliminates errors in f/stop from the lens or reciprocity failure effects from changing exposure time. Nonetheless, reciprocity errors should be small within normal exposure times and is more likely to give you errors than relying on the f/stop calibration of the lens. Paper grades are established as ISO standards and the information is often included in the paper data sheet. In any case, since there is a standard each grade should be the same among different papers. You should be able to tell if there is a major error this way. I think using the "wrong" set of filters can create as much as a one paper grade error in mid-grades but the greatest errors are usually at the ends of the range. So if you are going for grades around 1 to 3 the wrong filters should not introduce a large error. If the filters work OK with other papers the chances are that the paper has just gotten old. If it still makes good prints when a suitable filter is used you may just have to compensate for it by experimenting. BTW, I used to get AGFA paper in white boxes from Freestyle. I knew it was AGFA from the odor! AGFA always had a characteristic, distinctive smell, even years ago when it was sold as Ansco paper here. Of course the surface texture is also a tip off. Let me know what you find. -- Richard Knoppow Los Angeles WB6KBL |
#3
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Agfa MCP RC paper contrast
On 12/11/2010 10:17 AM Richard Knoppow spake thus:
[...] Nonetheless, reciprocity errors should be small within normal exposure times and is more likely to give you errors than relying on the f/stop calibration of the lens. I think you meant to write "is *less* likely to give you errors ..." here? (IOW, more accurate to change exposure times rather than f-stops.) -- Comment on quaint Usenet customs, from Usenet: To me, the *plonk...* reminds me of the old man at the public hearing who stands to make his point, then removes his hearing aid as a sign that he is not going to hear any rebuttals. |
#4
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Agfa MCP RC paper contrast
"David Nebenzahl" wrote in message .com... On 12/11/2010 10:17 AM Richard Knoppow spake thus: [...] Nonetheless, reciprocity errors should be small within normal exposure times and is more likely to give you errors than relying on the f/stop calibration of the lens. I think you meant to write "is *less* likely to give you errors ..." here? (IOW, more accurate to change exposure times rather than f-stops.) Yes, that's what I meant, somehow it got lost in the way to my fingers. -- Richard Knoppow Los Angeles, CA, USA |
#5
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Agfa MCP RC paper contrast
On 12/14/2010 11:19 AM, sreenath wrote:
Another problem I have is enlarger lamps. They are no longer available here, and I am using a Philips ""Cool tone" lamp, which is creamish, instead of white. They have done this by giving a special coating to make the light to look warm (cool tone!) I suspect it is cutting blue light causing drop in contract also. I will experiment with a magenta paper on the condenser to compensate for the "cool tone" light bulb. The bulb likely has as much or more to do with this than the filters or the old paper. The color temp of the bulb can have a huge effect on all this. Stephey |
#6
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Agfa MCP RC paper contrast
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#7
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Agfa MCP RC paper contrast
"sreenath" wrote in message ... On Dec 14, 11:29 am, "Richard Knoppow" wrote: "David Nebenzahl" wrote in message .com... On 12/11/2010 10:17 AM Richard Knoppow spake thus: [...] Nonetheless, reciprocity errors should be small within normal exposure times and is more likely to give you errors than relying on the f/stop calibration of the lens. I think you meant to write "is *less* likely to give you errors ..." here? (IOW, more accurate to change exposure times rather than f-stops.) Yes, that's what I meant, somehow it got lost in the way to my fingers. -- Richard Knoppow Los Angeles, CA, USA Actually, I am forced to use grade 4 filer routinely. So the grade error may be large as you have indicated. Another problem I have is enlarger lamps. They are no longer available here, and I am using a Philips ""Cool tone" lamp, which is creamish, instead of white. They have done this by giving a special coating to make the light to look warm (cool tone!) I suspect it is cutting blue light causing drop in contract also. I will experiment with a magenta paper on the condenser to compensate for the "cool tone" light bulb. -Sreenath You didn't say this was a cold light enlarger. If it is beware that the spectral output of flourescent lamps is quite different from incandescent lamps even when they _look_ the same. The paper and filters are made for incandescent lamps of a color temperature around 3K. Nearly all standard enlarger lamps will be close. If a cold light lamp is used some compensation must be applied in the form of additional filters. Even with the compensating filters the grade spacing and range will usually not match that for incandescent lamps. The data sheets for Ilford and older Kodak products (which may still be available) have some suggestions about the compensating filters. Even color head enlargers will not usually give you the full range of contrasts available from an incandescent lamp and regular filters although one can get reasonably close contrast and exposure matching over at least the center of the range. Probably your problems are coming from the light source and not the paper or filters. -- -- Richard Knoppow Los Angeles WB6KBL |
#8
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Agfa MCP RC paper contrast
"sreenath" wrote in message ... On Dec 16, 2:15 am, "Richard Knoppow" wrote: "sreenath" wrote in message ... On Dec 14, 11:29 am, "Richard Knoppow" wrote: "David Nebenzahl" wrote in message rs.com... On 12/11/2010 10:17 AM Richard Knoppow spake thus: [...] Nonetheless, reciprocity errors should be small within normal exposure times and is more likely to give you errors than relying on the f/stop calibration of the lens. I think you meant to write "is *less* likely to give you errors ..." here? (IOW, more accurate to change exposure times rather than f-stops.) Yes, that's what I meant, somehow it got lost in the way to my fingers. -- Richard Knoppow Los Angeles, CA, USA Actually, I am forced to use grade 4 filer routinely. So the grade error may be large as you have indicated. Another problem I have is enlarger lamps. They are no longer available here, and I am using a Philips ""Cool tone" lamp, which is creamish, instead of white. They have done this by giving a special coating to make the light to look warm (cool tone!) I suspect it is cutting blue light causing drop in contract also. I will experiment with a magenta paper on the condenser to compensate for the "cool tone" light bulb. -Sreenath You didn't say this was a cold light enlarger. If it is beware that the spectral output of flourescent lamps is quite different from incandescent lamps even when they _look_ the same. The paper and filters are made for incandescent lamps of a color temperature around 3K. Nearly all standard enlarger lamps will be close. If a cold light lamp is used some compensation must be applied in the form of additional filters. Even with the compensating filters the grade spacing and range will usually not match that for incandescent lamps. The data sheets for Ilford and older Kodak products (which may still be available) have some suggestions about the compensating filters. Even color head enlargers will not usually give you the full range of contrasts available from an incandescent lamp and regular filters although one can get reasonably close contrast and exposure matching over at least the center of the range. Probably your problems are coming from the light source and not the paper or filters. -- -- Richard Knoppow Los Angeles WB6KBL My enlarger lamp is incandescent lamp - frosted type (We cal it "milky" here). The coating given inside the bulb is creamish, not pure white as regular milky bulbs are. Philips calls them "cool" easy on the eyes, because they wont look bluish. I seem to have several problems with respect to light source, and perhaps the filters are really not to blame. I am considering LEDs as a source of light in enlarger, but building one is a way off. thanks for all the insight, Sreenath The original enlarging lamps were coated with a highly diffusing material, much more diffusing than normal "frosted" household lighting lamps. These are called "opal" lamps because the coating looks similar to true opal glass. Normal houshold lamps are not diffuse enough to give uniform illumination with most enlargers. Plus, most have the brand name stamped on the end of the bulb so that when used in a condenser enlarger it can be imaged on the print. Opal lamps are getting hard to find. I think Freestyle in Los Angeles still has some common size ones. I don't know if its economical to obtain them where you are but if so I suggest using them rather than some substitute. I think LED's do not have a uniform spectrum. Probably there is information on the web about this. Flourescent lamps use phosphores for most of their output so the spectrum is broken. While it may visually resemble incandescent light or daylight it does not have the same spectrum and may not react photographically in the same way as visually similar light from a source with a continuous spectrum like an incandescent lamp or sunlight. -- -- Richard Knoppow Los Angeles, CA, USA |
#9
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Agfa MCP RC paper contrast
On 12/16/2010 9:40 AM Richard Knoppow spake thus:
The original enlarging lamps were coated with a highly diffusing material, much more diffusing than normal "frosted" household lighting lamps. These are called "opal" lamps because the coating looks similar to true opal glass. Normal houshold lamps are not diffuse enough to give uniform illumination with most enlargers. Plus, most have the brand name stamped on the end of the bulb so that when used in a condenser enlarger it can be imaged on the print. Opal lamps are getting hard to find. I think Freestyle in Los Angeles still has some common size ones. Try Don's Bulbs: http://www.donsbulbs.com/cgi-bin/r/t.pl (hint: enter the manufacturer of your enlarger in the field marked "equipment search") -- Comment on quaint Usenet customs, from Usenet: To me, the *plonk...* reminds me of the old man at the public hearing who stands to make his point, then removes his hearing aid as a sign that he is not going to hear any rebuttals. |
#10
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Agfa MCP RC paper contrast
On 12/16/2010 7:05 PM David Nebenzahl spake thus:
Try Don's Bulbs: http://www.donsbulbs.com/cgi-bin/r/t.pl (hint: enter the manufacturer of your enlarger in the field marked "equipment search") Just a warning; Don's bulbs are not cheap. F'rinstance, here's an enlarger bulb--for $28 (15 in stock): http://www.donsbulbs.com/cgi-bin/r/b.pl/i|120v|75w|e26|s14|white|50h%5Eph140~ansi.html -- Comment on quaint Usenet customs, from Usenet: To me, the *plonk...* reminds me of the old man at the public hearing who stands to make his point, then removes his hearing aid as a sign that he is not going to hear any rebuttals. |
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