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> How to calculate correct push-processing time |
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#1
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How to calculate correct push-processing time
Dear analog enthousiasts,
I'm have a question regarding finding the right developing time / formula the info cannot be found on Massive Dev Chart. I have two roles of B&W film that I want to develop and both push one stop. One roll of IMAGO 320 (ARS) and one roll of 400 TMAX (Kodak). 1) My first question relates to finding the right developing time. I am using Ilfotec DD-X developer, but since Imago 320 is a rare film I imagine, there are no results for this combination on Massive Dev Chart. How should I go about this? The only developing times in MDC that show up from Ilford are done with ID-11 developer. 2) How do I calculate the right push-processing time based on the standard developing times? Doing a quick Google I found here that usually a 1-stop push can be achieved by using 1,5 times the standard developing time. But I'm confused as it also says that for TMax film a 1-stop does not have a longer developing time as an exception. Why is this the case? How do I push-process for Tmax 400 and how would I go about it for Imago 320? 3) Sometimes on Massive Dev Chart I find two different results on the same stock / developer combo. Is that just because two different people uploaded this that have a different preference? I am fairly new to the whole process of developing my own black & white film, my apologies if I am asking very simple questions but I'm very keen on understanding how this all works. Warm Regards, Twan (Film Student) |
#2
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Hello and welcome to FADU. There are times for 400 Tmax and DDX on the MDC and I would imagine times for 400 Tmax and DDX on the Ilford site. Look at the instruction sheet for DDX and it may list non Ilford films
As far as Imago 320 then you are right there is nothing on the MDC but looking at Imago 320 and ID11 the time is 7 minutes. Then go to a 400 speed Ilford film such as HP5+ and look at its development times to see if there is a time for ID11 and DDX There is a time and the time is 7.5 mins and for DDX 9mins which suggests that for a 400 film the DDX time is 20% more Add the 20% to the Imago and ID11 time This should get you close Mike |
#3
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Hi Twan and welcome to the forum. DDX is often referred to as liquid ID11 so there can't be much in it regarding times.
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MartyNL “Reaching a creative state of mind thru positive action is considered preferable to waiting for inspiration.” - Minor White, 1950 |
#4
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Twan, hello and welcome.
The Imago 320 data sheet gives times for standard and one stop push development in their own developer, respectively 8'30" and 10'. If you take that as a guide, you would add just under 18% to your standard time for DDX. The MDC shows times for TMax at 400 and 800, both in DDX 1+4 - 8' and 10'; so a 25% increase there. There are two times shown for each combination, one at 20 degrees and one at 24. That may answer your point 3. Don't be offended if you already know this; but 1+4 is not the same as 1:4. |
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