Jobo CPE-2
Jason Peters
I just purchased a CPE-2 processor and have been reading the Jobo manual
about B&W film development. I don't understand the reference to the min
amount of active developer. A 1520 tank has a capacity of two rolls of 120
or 35mm film.
I have been using D76 mixed 1:1 when using the inversion method do this was
not an issue. The manual states you need 240 ml to develope two rolls, but
they also state in their literature that a min of 110 ml of active developer
is require per roll of 36 exp. 35mm. They recommend incresing the amount of
developer by 30%.
Do most people use D76 straight or are they using more than 312+ ml to
develope two rolls? For example would you use the 240 ml for a single roll
of 120 or 35mm with D76 1:1? or say 330 ml mix 1:1 for two rolls?
Does this become more pronounced with the more rolls you want to develope?
If you add a 1530 extention you can develope up to 6 rolls of 120 or 5 rolls
of 35mm. Data sheets recommend 570 ml, but do you need 110ml/roll or 660 ml
for six rolls of 120 film? The manual recommends not to exceed 600 ml.
Thanks in advance,
Jason
John Hicks
<jason....@worldnet.att.net> wrote:
>I have been using D76 mixed 1:1 when using the inversion method do this was
>not an issue. The manual states you need 240 ml to develope two rolls, but
>they also state in their literature that a min of 110 ml of active developer
>is require per roll of 36 exp. 35mm. They recommend incresing the amount of
>developer by 30%.
I can see where it'd be confusing.
The amount of developer stock required per roll depends on the
developer you're using and the film you're developing; some
combinations seem pretty much immune to capacity considerations while
others put you right out there in deadman's corner if you're not
careful.
Since there are so many potential combinations manufacturers can
make capacity recommendations based only on what they _know_ works. If
you don't follow those recommendations you're on your own, and you can
determine whether or not your chosen combination works ok with the
amount of stock developer you use only by testing. The easiest way is
to develop two test rolls with the minimum required solution, look at
the negs and make some prints, and if all's well then obviously it
works ok.
That finding may not be valid for a different film or different
developer. You'd need to test.
Lately I've been working up to switching to the Jobo from manual
inversion agitation; the goal has been to find development times that
give a curve match for each method, and I've been using D-76H 1:3. In
Jobospeak that works out to 60ml developer stock per roll.
The results are that for HP5+, Delta 100 and TMX I've obtained
relatively exact matching curves for each film in D-76H 1:1 and 1:3
using both manual inversion agitation and the Jobo. Therefore 60ml
stock D-76H is sufficient for each of those films whichever the
agitation method. It's also enough for Fuji Acros 100 although I
wasn't trying to match curves for it.
Whether 60ml D-76H stock would be enough for _two_ rolls I have no
idea; I'd have to test to find out. But if I had two rolls to develop
I _know_ I could use 60ml stock per roll, which to match the minimum
solution required would be 120ml stock and 120ml water, or iow, D-76H
1:1.
So in a roundabout way I've answered your question. <g>
---
John Hicks
Huib Smeets
1)
The volumes noted on the drums are the amounts needed to fully submerge the
film in the chemicals, read it as an mininum quantity needed for any given
developer.
2)
beside the minimum fill quantity, you also need a certain mininum of
developer to correctly process a roll of film. To say it in other words: you
must fill enough developer molecules in the tank to react with the film.
This is very important to watch over when using diluted developers like D76
1:1 and others where you need to use more than the quantity noted on the
drum.
In theory, when using highly dilluted developers it could be that you cannot
use the max number of rolls because you would have to overfill the drum with
developer.
Hopes this helps.
Huib
"Jason Peters" <jason....@worldnet.att.net> wrote in message
news:aVSN6.31086$4f7.2...@bgtnsc06-news.ops.worldnet.att.net...
Richard Davis
before, it will work now, since all you are changing is agitation and tank
type.
But.... You have probably been using too little developer all along, and
probably haven't been getting full detail in the shadows. Kodak shows the
capacity of D-76 1:1 as 2 rolls per liter. That's 500ml per roll.
Don't be too alarmed... Ilford's ID-11, which is basically the same thing as
D-76, shows a capacity of 5 rolls per liter. This works out, by the way, to
be exactly in line with Jobo's recommendation.
http://www.kodak.com/cluster/global/en/professional/support/techPubs/j78/j78
.shtml
http://www.ilford.com/html/us_english/pdf/film_chem.pdf
At the very least I'd recommend going to 480 ml of D-76 for two rolls of
film in the Jobo drum.
Other changes to your method, like agitation, will probably have a bigger
impact on development.
"Jason Peters" <> wrote in message > I just purchased a CPE-2 processor and
have been reading the Jobo manual
> about B&W film development. I don't understand the reference to the min
> amount of active developer. ,,,,> I have been using D76 mixed 1:1 when
Jason Peters
I don't beleive you understood my comments regarding active developer. I
currently use the inversion method with patterson tanks. With this process
1 roll of 120 or 2 rolls of 35mm fit in my tank. I use 24 oz or 710 ml of
solution to process one roll of 120 film.
I am new to the rotary processor and was unclear as to the actual capacity
of the tanks with regards to D76 mixed 1:1. From what I am reading it
sounds like the solution is testing.
I have no history with the Jobo and was trying to find out if others have
had sucess or failure with the max number of rolls published by Jobo or if
they typically use straight D76 or other developers.
Thank you all for your input.
Jason
Richard Davis <drd...@hotmail.com> wrote in message
news:FjuO6.59$G51....@news.uswest.net...
Georges Giralt
> Hi Everyone,
Hi Jason,
>
> I just purchased a CPE-2 processor and have been reading the Jobo manual
> about B&W film development. I don't understand the reference to the min
> amount of active developer. A 1520 tank has a capacity of two rolls of 120
> or 35mm film.
>
> I have been using D76 mixed 1:1 when using the inversion method do this was
> not an issue. The manual states you need 240 ml to develope two rolls, but
> they also state in their literature that a min of 110 ml of active developer
> is require per roll of 36 exp. 35mm. They recommend incresing the amount of
> developer by 30%.
>
As far as I've understood the Jobo instruction, they ask to compensate
for greater oxydation due to the permanent agitation of the mixture in
the tank.
> Do most people use D76 straight or are they using more than 312+ ml to
> develope two rolls? For example would you use the 240 ml for a single roll
> of 120 or 35mm with D76 1:1? or say 330 ml mix 1:1 for two rolls?
>
> Does this become more pronounced with the more rolls you want to develope?
> If you add a 1530 extention you can develope up to 6 rolls of 120 or 5 rolls
> of 35mm. Data sheets recommend 570 ml, but do you need 110ml/roll or 660 ml
> for six rolls of 120 film? The manual recommends not to exceed 600 ml.
>
My finding are that it is quite impossible to process the maximum number
of films in a CPE2 (unless you use something like Rodinal). I use PMK or
Xtol. Kodak state that you need 100CC stock for _one_ film (135 or 120,
quite the same film surface). If you dilute it 1+2 you need 300 CC for
one film (which is above the Jobo's minimum 240 CC). Taking into account
the 600 CC hard limit "not to strain the motor" you can only process
_two_ films at a time in a Jobo CPE2.
The situation is even worse with PMK as Gordon Hutchings state that you
need 500 CC working solution for one film.... And that you often need to
split that amount in two batches as the PMK working solution oxydize
badly with continuous motion.
The situation is better if you use Rodinal, with wich I've had success
with a low 6CC stock for one film. To err on the safe side using rotary,
I will some day test 10cc Rodinal for one film in my Jobo, which will go
for 5 or 6 films in a tank (600 cc limit)
I've been told, but I've not tested this, that you can prepare the exact
amount of working solution you need for the batch of film you can put in
the Jobo (Xtol example 1+2: 6 films need 600cc stock plus 1200 CC water
for a grand total of 1800 CC) and split the volume by 600 and process
for a portion of the time with the first 600 cc, dump, replace with
fresh chemistry, and continue until you have reached the desired time.
(in the above example this will go for three passes, each for one third
of the total time). I wonder if this method is acceptable and if things
are so linear....
Regards
> Thanks in advance,
>
>
> Jason
--
Georges Giralt Administrateur Système et Réseaux
Silogic 78 Chemin des Sept-Deniers 31200 Toulouse
Tel +33 (0)5 61 13 53 00 Fax +33 (0)5 61 57 96 60
Gdoces
>amount of working solution you need for the batch of film you can put in
>the Jobo (Xtol example 1+2: 6 films need 600cc stock plus 1200 CC water
>for a grand total of 1800 CC) and split the volume by 600 and process
>for a portion of the time with the first 600 cc, dump, replace with
>fresh chemistry, and continue until you have reached the desired time.
>(in the above example this will go for three passes, each for one third
>of the total time). I wonder if this method is acceptable and if things
>are so linear.
I don't know whether this relates to your question, but I have attempted to
develop film using one particular dilution of developer for a short period of
time, dumping that solution and than adding a weaker dilution to complete
development. This was in an attempt to do compensation development. The
results were somewhat of a disaster. My film was streaked which I attributed
to the delay in time between dumping the first solution and pouring in the
second. If you are going to attempt what you outlined, I would strongly
suggest that you sift the film from one tank of developer to the another tank
with very little delay. Otherwise you might end up with streaks or varying
density on your film.
