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#1
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Ilford processing times (Pan F)
After my recent success with TMX, I delved into my freezerful of film
and pulled out a roll of Pan F I want to shoot. But I'm a bit mystified by the enclosed processing instructions. Was thinking of using D-76, and they have times for both this and ID-11 (same times, since the same developer, except that they list ID-11 at 1+1 but not D-76, though I assume I can also dilute it). But they show the same times for both ISO 25 and 50 exposure. Can this be correct? Other developers show different times for the two speeds. They also show times for Perceptol, but not Microdol-X. Richard K., you said these developers were equivalent: would you use the same times for both of these? The Humumgous Massive Really Really Big Dev Chart (http://www.digitaltruth.com/devchart.php) shows different times for these (9 min. for Perceptol vs 12 min. for Microdol; should I just use their recommendations? -- The fashion in killing has an insouciant, flirty style this spring, with the flaunting of well-defined muscle, wrapped in flags. - Comment from an article on Antiwar.com (http://antiwar.com) |
#2
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The MDC is not as reliable as the Manufacturers own data because we don't know who or how the poster reached their figures.
Ilford's Data is here and a far better starting point. http://www.ilfordphoto.com/Webfiles/...6115811391.pdf Ian Quote:
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#3
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Ilford processing times (Pan F)
On 7/22/2010 4:45 AM IanG spake thus:
[corrected for top-posting, and WTF happened to my quoted text?] David Nebenzahl;884098 Wrote: After my recent success with TMX, I dTHe MDC is unfortunately not elved into my freezerful of film and pulled out a roll of Pan F I want to shoot. But I'm a bit mystified by the enclosed processing instructions. Was thinking of using D-76, and they have times for both this and ID-11 (same times, since the same developer, except that they list ID-11 at 1+1 but not D-76, though I assume I can also dilute it). But they show the same times for both ISO 25 and 50 exposure. Can this be correct? Other developers show different times for the two speeds. They also show times for Perceptol, but not Microdol-X. Richard K., you said these developers were equivalent: would you use the same times for both of these? The Humumgous Massive Really Really Big Dev Chart (http://www.digitaltruth.com/devchart.php) shows different times for these (9 min. for Perceptol vs 12 min. for Microdol; should I just use their recommendations? The MDC is not as reliable as the Manufacturers own data because we don't know who or how the poster reached their figures. Ilford's Data is here and a far better starting point. http://www.ilfordphoto.com/Webfiles/...6115811391.pdf Thanks; I should have checked that first. As it turns out, the Ilford sheet agrees with the Massive Dev Chart. What it doesn't agree with is some of Ilford's own printed information: both the inside of the film carton and the large Ilford film processing chart I have (came with a box of paper, I think) have the same times for ISO 25 and 50 for three developers (ID-11, Microphen and D-76) which can't be correct. The PDF you gave us a link to appears to have the correct data. Must be typos, I guess. So now my only dilemma is whether I should de-rate the film at 25 or go for the extra stop (50) and develop longer (I plan on using Microdol-X). Any opinions on this? -- The fashion in killing has an insouciant, flirty style this spring, with the flaunting of well-defined muscle, wrapped in flags. - Comment from an article on Antiwar.com (http://antiwar.com) |
#4
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Ilford processing times (Pan F)
On 7/22/2010 11:39 AM Digitaltruth spake thus:
The Massive Dev Chart is more reliable than the published data sheets released by manufacturers. Why? Because it incorporates the official information that you will find in the manufacturer's data sheets, AND it includes additional user submissions and amendments. I've spent 15 years collating and editing this data, which is a lot more time than the manufacturers spend on it. While some manufacturers, most notably Ilford and Fuji, provide excellent data based on their own in-house analysis, many other manufacturers are far less thorough. In fact, there are several official data sheets currently being published which include data from the Massive Dev Chart as the primary source, even though I doubt the manufacturers have ever tested it themselves. [snip] Well, I for one very much appreciate, and have made much use of, your Humungous Ginormous Dev Chart. My hat is off to you. And as I pointed out in another post here, some of Ilford's own documentation has obviously erroneous data: both the inside of the film carton and the large Ilford Film Processing Chart that I have show identical (and therefore obviously incorrect) times for ISO 25 & 50 times for three different developers for Pan F. Your chart agrees perfectly with the Ilford PDF supplied elsewhere in this thread, which appears to be correct. -- The fashion in killing has an insouciant, flirty style this spring, with the flaunting of well-defined muscle, wrapped in flags. - Comment from an article on Antiwar.com (http://antiwar.com) |
#5
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Ilford processing times (Pan F)
"Digitaltruth" wrote in message ... The Massive Dev Chart is more reliable than the published data sheets released by manufacturers. Why? Because it incorporates the official information that you will find in the manufacturer's data sheets, AND it includes additional user submissions and amendments. I've spent 15 years collating and editing this data, which is a lot more time than the manufacturers spend on it. While some manufacturers, most notably Ilford and Fuji, provide excellent data based on their own in-house analysis, many other manufacturers are far less thorough. In fact, there are several official data sheets currently being published which include data from the Massive Dev Chart as the primary source, even though I doubt the manufacturers have ever tested it themselves. One of the recurrent questions about the Massive Dev Chart is why Ilford's published times for developing film in Kodak D-76 are only included if they are the same as the published times for ID-11. The reason for this is because the chemical composition of these two developers is almost identical. In fact, the difference is sufficiently small so as to be negligible for all intents and purposes. Ilford's data for its own products is highly reliable, so when there is a significant variance between times for third-party chemicals such as D-76, then it is safe to assume that the testing procedure was different and should not be relied on if it does not match that of ID-11. Perceptol and Microdol-X are not the same developer, although they have similar characteristics. Different times are required, so you should use the data for each developer in The Massive Dev Chart to provide the required starting point. If you study official data sheets you will notice that manufacturers often update the times even though no changes have been made to their products. Conversely, Kodak changed many times when they modified the film base on several products a few years back, but other published studies showed that the original times were more accurate. You can also see that, famously in the case of Agfa, they release different data in different countries. Trusting something just because it is printed by the manufacturer is does not offer any guarantee of accuracy. The most important part of any issues regarding accuracy of development times is to understand that ALL times are starting point recommendations, regardless of the source, and it is up to the individual user to use these starting points to determine the optimum development in relation to subject contrast, print contrast and enlarging equipment. --Jon Mided http://www.digitaltruth.com If you check the MSDS you will find that Microdol-X and Perceptol are essentially identical. I say essentially because both manuacturers probably have additions in the form of sequestering agents that do not show up in MSDS. Also, Kodak has patented method of preparing some of the ingredients they use. The published formulas for D-76 and ID-11 are the same but the packaged developers may be different. The MSDS for D-76 shows it to be the buffered formula similar to the published D-76d. Packaged ID-11 may also be buffered but no buffering agent shows up in the MSDS. Manufacturers' data is generated by use of proper sensitometry, at least its supposed to be and I think Kodak and Ilford data are reliable. One difference between the two is that some time ago Ilford stopped using the ISO method to rate film. The ISO standard is correct for a contrast index about right for diffusion enlarging and contact printing. When lower contrast is desired for condenser enlargers the development must be adjusted with a consequent change in effective film speed. Ilford appears to use a contrast index mid-way between condenser and diffusion values. This results in a slight lowering of effective speed when the film is developed to diffusion contrast and accounts for the differnce in developing times for Ilford film given by Ilford and some others. -- -- Richard Knoppow Los Angeles, CA, USA |
#6
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Ilford processing times (Pan F)
"David Nebenzahl" wrote in message .com... After my recent success with TMX, I delved into my freezerful of film and pulled out a roll of Pan F I want to shoot. But I'm a bit mystified by the enclosed processing instructions. Was thinking of using D-76, and they have times for both this and ID-11 (same times, since the same developer, except that they list ID-11 at 1+1 but not D-76, though I assume I can also dilute it). But they show the same times for both ISO 25 and 50 exposure. Can this be correct? Other developers show different times for the two speeds. They also show times for Perceptol, but not Microdol-X. Richard K., you said these developers were equivalent: would you use the same times for both of these? The Humumgous Massive Really Really Big Dev Chart (http://www.digitaltruth.com/devchart.php) shows different times for these (9 min. for Perceptol vs 12 min. for Microdol; should I just use their recommendations? You will notice that Kodak also rates T-Max 100 and 400 at double speed with normal development. The differece between the two exposure indices is a difference in overall density and in shadow detail, the contrast remains the same. When the ASA system of speeds was introduced in 1943 it included a safety factor of two so that all film speeds were half the value actually determined by the test method. For some reason this was thought to be a good idea even though the research at Kodak from which the standard was adopted was intended to find the _minimum_ exposure possible for good tonal rendition. This was because film is somewhat less grainy and somewhat sharper for thin images. Nontheless, the lower speeds were recommended. I think the reason is that Kodak, in particular, wanted to insure amateur users would get a printable image and overexposure does less damage than underexposure. In 1958 when the ASA adopted a modification of the then new DIN standard, which was much easier to measure than the minimum gradient method previously used, they also dropped the fudge factor and all film speeds were doubled! That put the manufacturers of "magic" speed increasing developers out of business. They all knew and counted on the fact that all films were actually double the speed given by the ASA. Kodak actually talks about this in the introduction to the film booklet included in the _Kodak Reference Handbook_ but its obscured by recommending increased speed only to essentially professionals. In any case many photographers find that increasing exposure from that given by the ISO speed often results in better shadow rendition and, with modern thin-emulsion film has little effect on grain or sharpness. -- -- Richard Knoppow Los Angeles, CA, USA |
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