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#11
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Adjusting development for temperature
"Andrew Price" wrote in message
... On Sun, 6 Apr 2008 18:26:09 -0500, Pico wrote: and then compensate for the actual temperature of your basement, using their time/temperature chart: http://www.digitaltruth.com/images/time.gif And keep your fingers crossed and hope by chance the chart is right. It's a starting point, nothing more. Most people who are seriously interested in developing their own film take notes and compare the results at different temperatures and dilutions. It may be a stopping point. If the full chemistry isn't active at 60F, nothing might happen. But over the short temperature range quoted (+14 to +24) it is a starting point, and one recommended by Ilford and other manufacturers of black and white film. Bull****. Those are the recommended ranges, bottom and top, not higher and not lower than that range. Some of their film development specs are flat out guesses, Hmm... supporting data? some upon a recommendation of a quesitonable source. Do you have any convincing supporting evidence of that assertion? I would, but I forgot the guy's name. Spanky or something like Uranium Committee. Yep, that's a pseudo he used. Search for 'dougnut boy', his lifelong masterpiece done in high school fifty years ago. One of those sources is a hairbrained maniac who frequented this place and hasn't developed a roll of film for forty years. Being more specific would add credulity to that statement. I wrote that I would if I could recall his name, but some things are worth forgetting. I don't know how long you have been around, and I don't want to bother looking, but you might remember if you ... wait, It is Michael something. Pure impressionism. Indeed - but whose? Michael S (spook, spoor, smegma, something) |
#12
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Adjusting development for temperature
On 4/7/2008 5:43 PM jjs spake thus:
"Andrew Price" wrote in message ... Do you have any convincing supporting evidence of that assertion? I would, but I forgot the guy's name. Spanky or something like Uranium Committee. Yep, that's a pseudo he used. Search for 'dougnut boy', his lifelong masterpiece done in high school fifty years ago. Close; you're talking about (dare I invoke his name here, lest he come back to torment us?) Michael Scarpitti, aka "Uranium Committee" aka "Waffle Boy". -- The best argument against democracy is a five-minute conversation with the average voter. - Attributed to Winston Churchill |
#13
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Adjusting development for temperature
"David Nebenzahl" wrote in message s.com... Close; you're talking about (dare I invoke his name here, lest he come back to torment us?) Michael Scarpitti, aka "Uranium Committee" aka "Waffle Boy". Yeah, that's the name! He's the guy who claims that Agfa Brovira was overly contrasty and he could never get a good print. (Its grades were about one lower than Kodak, back when they both made graded paper, and Agfa went from 0 to 6.) He also claimed that the Leica was the best camera in the world, and the ****amat enlarging lenses were the very best, and that photography could not possibly be an art. Didn't he rename his masterpiece to Doughnut Boy? Or is that his new moniker? Anyway, he claimed to be an authority on B&W film development and his recommendation(s) were in Digital Truth. Be suspicious of ANYTHING that says it is the truth. Anyway, OP, so develop some Tri-X 125 in 60F or colder water and let us know how it goes for you. Or don't. I would choose a more active developer for cold water, something recommended for such an application. But WTF do I know? I just started taking picture and making wet prints FIFTY years ago. My next post will be more to the point of the post. Cold development solutions (no pun). |
#14
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Adjusting development for temperature
OK, I don't have the reference book for cold weather processing on-hand. It
must be in storage. Leitz had good information in one of their earlier books. I might find it this weekend. In the meantime, an *authoritative source mentions the rule of thumb mentioned earlier - quoting from the book, "a general rule of thumb for the range of 65 to 95F is that a decrease of 10F increases the development time 1.5 times." and they mention that the rule of thumb is just that - am approximation. Note that they do not include temperatures below 65F because lower temperature solutions have more profound differences; they are not covered by the rule of thumb. * source: SPSE Handbook of Photographic Science and Engineering 1,416 pages |
#15
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Adjusting development for temperature
On Apr 7, 4:49*am, Peter wrote:
On Apr 6, 9:46*pm, wrote: Given that the basement is still coolish from the winter, what would be the best development time factor for D76 at 60 deg F (15 deg C)? .... Thanks for any comments. You have mentioned a number of points of uncertainty: long hiatus old film long time since exposure You haven't mentioned much about the rest of your technique (e.g., how sure are you that you used the correct exposure allowing for old film & etc., why not keep the solutions in a warm room, load the film in a tank in your dark room and develop the film at a more convenient temperature in a warm room, how accurated is your time keeping, temperature measurement and how consistently correct are the solutions & etc). A digital timer is being used, with lap times for each step in the processing. A review of the split times shows that draining the old tank being used is taking longer than expected, but longer time is not the problem here. It is possible that the film being at room temperature for over a year was a factor. The latest roll turned out with good density. More later. Personally, I've had poor experience with Plus-x in D-76 at cold temperatures. *I settled on never developing it below 65F. *That was decades ago and I forget the details. *Perhaps I was wrong. Given that the Kodak datasheets do not go below 65 deg F, this might well be the case. Even so, you need to prove you can get a correctly exposed roll of your old film developed to normal density and contrast. *To do this, I thing you need to plan on trying more than one roll of test pictures (sheet film is an attractive alternative for such experiments, if available). Getting a good roll done was a priority for me, too. A heater in a small area took the temperature of the chemicals up to 22 deg C over the course of the day and processing on another roll was done at that temperature. This time, D76 at 1:1 dilution was used, and the results look good. There is a certain satisfaction in the process of developing film, sight unseen for most of the processing, and finally seeing the results turn out well. |
#16
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Adjusting development for temperature
wrote in message ... On Apr 6, 5:38 pm, Andrew Price wrote: On Sun, 6 Apr 2008 12:46:05 -0700 (PDT), wrote: [---] I am just getting back into B&W film again, after a long hiatus. Any comments on an appropriate development time for the next roll? Check the times for the specific film you're using at: http://www.digitaltruth.com/devchart.html and then compensate for the actual temperature of your basement, using their time/temperature chart: http://www.digitaltruth.com/images/time.gif Thanks. This chart is similar to the values in the table, but maybe using a different temperature coefficient? As you can see, the temperature scale is linear while the time scale is logarithmic. Perhaps the temperature coefficient is the slope of the line. Richard Knoppow wrote: The temperature coefficient varies with the developer and to some degree with the film so there is no absolute rule. For some guidance check Kodak film data sheets. Most have graphs showing the variation of development time with temperature as well as showing development times for various temperatures on the charts. ... Why didn't I think of looking there? The film I am using has been discontinued a few years (stored in the freezer meanwhile). The chart for Plus-X only goes down to 65 deg F, though. Maybe Kodak does not recommend processing at low temps? Thanks, anyway. Plus-X tech sheet: http://www.kodak.com/global/en/profe...18/f4018.jhtml 65F used to be the "standard" temperature up to the early 1940's when it was increased to 68F due to better emulsion hardening in manuacture. Much below this one encounters problems due to hydroquinone loosing activity, but that depends on the pH of the developer. Low temperature development is possible and Kodak used to have a brochure on how to do it. The simple chemical rules for the variation of rates of reaction due to temperature and concentration do not always apply directly to actual photographic processes because they are complex. For instance, development and fixing are affected by the diffusion rate into the emulsion which is partly dependant on temperature but depends on the history of the gelatin so its not simple. Kodak appears not to recommend using some developers below relatively high temperatures, for instance diluted T-Max. In some of the older Kodak charts a preferred temperature was indicated by printing the temp in bold type. This was around 75F for T-Max and some others. Kodak never stated the reason for this but, usually, they had good reasons. I've found that Kodak's data is usually quite accurate although they occasionally blunder. -- --- Richard Knoppow Los Angeles, CA, USA |
#17
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Adjusting development for temperature
"jjs" wrote
"a general rule of thumb for the range of 65 to 95F is that a decrease of 10F increases the development time 1.5 times." Leading back to first-year chemistry ... http://en.wikipedia.org/wiki/Arrhenius_equation where the rate of a reaction doubles every 10C. A variation on the universal equation: Something = Something Else * e ^ -(Energy of the thing / k * T) Where k is Boltzman's constant and T is temperature relative to absolute zero. -- Nicholas O. Lindan, Cleveland, Ohio Darkroom Automation: F-Stop Timers, Enlarging Meters http://www.darkroomautomation.com/index2.htm n o lindan at ix dot netcom dot com |
#18
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Adjusting development for temperature
In article ,
Nicholas O. Lindan wrote: "jjs" wrote "a general rule of thumb for the range of 65 to 95F is that a decrease of 10F increases the development time 1.5 times." Leading back to first-year chemistry ... http://en.wikipedia.org/wiki/Arrhenius_equation where the rate of a reaction doubles every 10C. A variation on the universal equation: Something = Something Else * e ^ -(Energy of the thing / k * T) Where k is Boltzman's constant and T is temperature relative to absolute zero. Unfortunately, there are several reactions going on at once in a typical photographic development bath. For example, consider a tank full of D76: the primary development agent (the metol) is being exhausted by developing the film, and regenerated by stealing electrons from the other developing agents. A buffer reaction is keeping the pH of the solution stable, at the same time. More complex developers will have sequestering agents grabbing up development-inhibiting reaction products and holding them in solution, etc. -- and all these reactions have different energies, thus proceed at different rates. Get below or above some threshold temperature, and the overall reaction won't run as designed, period, and the characteristic curve of the resulting negatives will be...different. In any event, if you actually fit curves to the time/temperature data for common films and developers (at some constant exposure and density) you will find that they are, at least, shallow 2nd-order curves -- not linear. And that's within a fairly narrow temperature range, all bets are off once you get outside there. The film/developer testing page on Paul Butzi's site has some nice examples of the data and the curves that fit it, and they are *not* straight lines. -- Thor Lancelot Simon "The inconsistency is startling, though admittedly, if consistency is to be abandoned or transcended, there is no problem." - Noam Chomsky |
#19
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Adjusting development for temperature
"Nicholas O. Lindan" wrote in message ... "jjs" wrote "a general rule of thumb for the range of 65 to 95F is that a decrease of 10F increases the development time 1.5 times." Leading back to first-year chemistry ... http://en.wikipedia.org/wiki/Arrhenius_equation where the rate of a reaction doubles every 10C. Perhaps for quite similar chemicals separately, but our developers are complex mixes. |
#20
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Adjusting development for temperature
On Apr 7, 11:04*pm, "jjs" wrote:
... Anyway, OP, so develop some Tri-X 125 in 60F or colder water and let us know how it goes for you. Or don't. I would choose a more active developer for cold water, something recommended for such an application. But WTF do I know? I just started taking picture and making wet prints FIFTY years ago. My next post will be more to the point of the post. Cold development solutions (no pun). Hi, JJS. Did you have any recommendations for cold water processing? A check of the Manual I have shows no specific cold water formulations. However, it did list a tropical developer that can be used to 32 deg C, useful for when summer comes. |
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