klix Posted July 29, 2003 Share Posted July 29, 2003 Summertime, and my tap water is coming out a 75 deg F; I know I can use refrigerated water or even ice to get the temp down, but I came across this post from a couple of years back...Can anyone validate this?? I suppose I could shoot a roll of film and try, but thought I'd try here to see if anyone's attempted this.<p><p> <i>Aaron Sussmans book from the late 60's "Amatuer Photographers Handbook".<p><p> <b>"Given the developing time at 68 degrees, you convert to the time at any other temperature by multiplying the given time by the desired temperature factor T. <p><p> To convert from the time at any temperature other than 68 degrees, to any other temperature, you divide the time of the given temperature by its own factor and then multiply by the factor of the desired temperature." <p><p> Temp in Farenheit followed by factor <p><p></b> <ul> <li>64 deg F factor 1.23 <li>65 deg F factor 1.16 <li>66 deg F factor 1.10 <li>67 deg F factor 1.05 <li>68 deg F factor 1.00 <li>69 deg F factor .95 <li>70 deg F factor .90 <li>71 deg F factor .85 <li>72 deg F factor .81 <li>73 deg F factor .78 <li>74 deg F factor .75 <li>75 deg F factor .72 <li>76 deg F factor .69 <li>77 deg F factor .66 </ul> Link to comment Share on other sites More sharing options...
group 11 Posted July 29, 2003 Share Posted July 29, 2003 from the ilford site: Link to comment Share on other sites More sharing options...
lex_jenkins Posted July 29, 2003 Share Posted July 29, 2003 </i> Thanks, RJ, Will, good info. Link to comment Share on other sites More sharing options...
group 11 Posted July 29, 2003 Share Posted July 29, 2003 i forgot to add this....: i'm attempting to verify your factoring by taking the plots from the charts and matching them up. i'll let you know how it goes. Link to comment Share on other sites More sharing options...
richard_urmonas Posted July 29, 2003 Share Posted July 29, 2003 Careful. Different developers behave differently with temperature change. The Ilford chart is for MQ and PQ developers. If you go outside the range of the Ilford chart, things can change rather dramatically, as the super additive effect changes (much less effective at low temperatures, various effects at high temperatures). The safest path is to download a datasheet for the developer you are using, and look at what the manufacturer suggests. Link to comment Share on other sites More sharing options...
group 11 Posted July 30, 2003 Share Posted July 30, 2003 oddly it worked quite well for me w/rodinal. spot on, actually. go figure. Link to comment Share on other sites More sharing options...
klix Posted July 30, 2003 Author Share Posted July 30, 2003 Just tested a roll of Neopan 400, rated nominally, using XTOL 1+2 --Lex's favorite :-). Massive Dev Chart lists this combo at 12min 30sec at 68 deg F; applying this chart for 75 deg F calcs out to 9 mins (factor .72) Results look consistent with my usual results at 68 deg F. Link to comment Share on other sites More sharing options...
chris_waller Posted July 30, 2003 Share Posted July 30, 2003 As Richard says, it varies with the type of developer. As a rule of thumb and in the absence of better information I decrease dev time by 10 percent per degree C above 20 C (approx. 5 percent per degree F) and increase by 10 percent per degree C below 20 C. which corresponds to the above table. Rodinal is notably linear against temperature having a single developing agent but MQ formulations differently against temperature - the activity of quinol (hydroquinone) drops sharply below 18 C. Link to comment Share on other sites More sharing options...
tim_curry Posted July 31, 2003 Share Posted July 31, 2003 I'm using PMK Pyro and have found the recommendation from "The Book Of Pyro" to be correct, 4% per degree above 70f. I've developed Efke 25 at up to 82f with no trouble and even results. Each developer may respond differently to temperature increase. If you have no other information, use the tables above. Otherwise, try finding the correct data for each developer if it exists. It is worth a bit of research and caution. Link to comment Share on other sites More sharing options...
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