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Jobo & Pre Rinse?



 
 
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  #1  
Old July 23rd 11, 08:16 PM
Darkroom User Darkroom User is offline
Junior Member
 
First recorded activity by PhotoBanter: Aug 2010
Posts: 27
Default 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  
Old July 23rd 11, 11:59 PM posted to rec.photo.darkroom
Martin Riddle
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Posts: 69
Default 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  
Old July 24th 11, 01:17 AM posted to rec.photo.darkroom
Frank Pittel
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Posts: 92
Default 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  
Old July 24th 11, 05:00 AM posted to rec.photo.darkroom
Mr. Strat
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Posts: 1,089
Default 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  
Old July 28th 11, 01:30 AM posted to rec.photo.darkroom
Richard Knoppow
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Posts: 751
Default 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  
Old August 18th 11, 05:01 AM posted to rec.photo.darkroom
Thor Lancelot Simon
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Posts: 163
Default 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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