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#1
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Jobo & Pre Rinse?
I have bought a Jobo CPE2 with the lift and a 1540 drum with reels.
I want to use TMax 100 and 400 in D76 1:1. The instruction book recommends a 5 minute pre rinse before pouring in the developer. Is it essential to pre soak films if using a Jobo? Does anyone here use a Jobo, if so, what is your method? |
#2
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Jobo & Pre Rinse?
"Darkroom User" wrote in message news I have bought a Jobo CPE2 with the lift and a 1540 drum with reels. I want to use TMax 100 and 400 in D76 1:1. The instruction book recommends a 5 minute pre rinse before pouring in the developer. Is it essential to pre soak films if using a Jobo? Does anyone here use a Jobo, if so, what is your method? -- Darkroom User Send them an email, they will answer your question. http://www.jobo.com/web/Contact.171.0.html I had some problems with their 3-bath kit is the past, and they were very responsive. Cheers |
#3
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Jobo & Pre Rinse?
That's a loaded question and I'm sure you're going to get a lot of different answers.
I always used a prewash for a couple of reasons. The first is that without the prewash my development times were to short at under 5min. The second was that I get more even development. When I didn't use the prewash I noticed problems with streaking and uneven development. One thing that's very important is that if you use a multi reel tank you have to fill the tank with reels or you'll get horrible streaking. I ran into this while using very dilute developers and needed to use the larger tanks to get the developer volume I needed. As to my method I bring the wash water to temp in the tempering tank. In my never humble opinion that has the added benefit of bringing the reels and film to temp so when you add the developer the temp and therefore contrast is more consistent. Frank Darkroom User wrote: : I have bought a Jobo CPE2 with the lift and a 1540 drum with reels. : I want to use TMax 100 and 400 in D76 1:1. The instruction book : recommends a 5 minute pre rinse before pouring in the developer. Is it : essential to pre soak films if using a Jobo? : Does anyone here use a Jobo, if so, what is your method? : -- : Darkroom User -- ------------------- Keep working dumbo needs the money |
#4
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Jobo & Pre Rinse?
In article , Darkroom User
wrote: I have bought a Jobo CPE2 with the lift and a 1540 drum with reels. I want to use TMax 100 and 400 in D76 1:1. The instruction book recommends a 5 minute pre rinse before pouring in the developer. Is it essential to pre soak films if using a Jobo? Does anyone here use a Jobo, if so, what is your method? Don't know. I always used Nikkor tanks and reels. |
#5
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Jobo & Pre Rinse?
"Darkroom User" wrote in message news I have bought a Jobo CPE2 with the lift and a 1540 drum with reels. I want to use TMax 100 and 400 in D76 1:1. The instruction book recommends a 5 minute pre rinse before pouring in the developer. Is it essential to pre soak films if using a Jobo? Does anyone here use a Jobo, if so, what is your method? -- Darkroom User There are two reasons Jobo reccomends a pre-soak. One is that it saturates the emulsion and contols the rate of uptake of the developer. That insures it is taken up evenly to eliminate blotching. The development is also slowed somewhat because the "induction time", that is, the time between immersing the film in the developer and the time the image begins to appear, is lengthened. Because of the very rapid agitation in the drum the development time is quite short compared to other non-machine methods so that increasing it a little also tends to insure uniformity. The second reason is to temper the tank. This is more necessary for color development done at elevated temperature so that the temperature of the developer is not suddenly changed when entering the tank. Kodak recommends a pre-soak for hand processing of sheet film in a tray to prevent the sheets from sticking. While some manufacturers seem to discourage pre-soaking I can find no very good reason not to. Elsewhere in this thread it is recommended that D-76 not be used. Some seem to have a predjucide against this developer but it works very well for many films. Somewhat higher speed and slightly finer grain can be had with Xtol. There are other good developers but D-76 remains the standard of comparison after some eighty-five years. If Jobo has recommended times I would at least start with them. I think Kodak may give drum development times for some film and developer combinations. Otherwise you have to experiment. Times in a machine like the Jobo are likely to be surprizingly short because of the very effective agitation. -- Richard Knoppow Los Angeles, CA, USA |
#6
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Jobo & Pre Rinse?
In article ,
Richard Knoppow wrote: There are two reasons Jobo reccomends a pre-soak. One is that it saturates the emulsion and contols the rate of uptake of the developer. That insures it is taken up evenly to eliminate blotching. The development is also slowed somewhat because the "induction time", that is, the time between immersing the film in the developer and the time the image begins to appear, is lengthened. Because of the very rapid agitation in the drum the development time is quite short compared to other non-machine methods so that increasing it a little also tends to insure uniformity. The second reason is to temper the tank. This is more necessary for color development done at elevated temperature so that the temperature of the developer is not suddenly changed when entering the tank. I strongly recommend *against* use of a pre-soak when developing color film in a Jobo. I think if you peruse the various web fora you will find a number of former Kodak chemists making the same recommendation-against. Many modern Kodak materials (at least) are manufactured in such a way that developer penetration into the emulsion is controlled by an "overcoat" of non-sensitized material. Among other issues, pre-soaking defeats this, so that you are not developing the film as its designers intended and may not obtain the same curves they publish, even with the same developer at the same concentration. A nuisance with black and white materials, but a more serious issue with color ones. Kodak recommends either the use of temperature controlled hot air blown into the tank instead of a presoak (I do not know what kind of rotary-tube machine can do this) or a longer preheat with the tank in the water bath but no liquid in the tank. I use the latter method and have always had good results even with processes with very short times for some steps such as C-41RA. -- Thor Lancelot Simon "All of my opinions are consistent, but I cannot present them all at once." -Jean-Jacques Rousseau, On The Social Contract |
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