Clarification on Rotary processing of Adox.

[Radost]

I need a little clarification:
It says the rule of thumb is to decrease development by 10-15%.
This is common knowledge.
But then it says to overexpose film as well?
It seams counter intuitive.

 

[pentaxuser]

I need a little clarification:
It says the rule of thumb is to decrease development by 10-15%.
This is common knowledge.
But then it says to overexpose film as well?
It seams counter intuitive.


View attachment 339784

A new one on me but might the last paragraph help account for Sirius' point about needing to lengthen development of the 3 films he mentions? Pity it's a bit vague on what percentage over exposure is required and there is no explanation why the decrease in speed occurs if the temperature is kept constant

I am puzzled

pentaxuser

 

[albada]

Intermittent agitation lets shadows develop more than highlights because highlight-development is slowed down due to exhaustion.
Rotary develops both shadows and highlights at the same rate. To prevent overdeveloping highlights, you must reduce development-time. That causes shadows to have less development. That causes film speed (EI) to drop. To compensate for that, you need to expose a little more.

Mark

 

[pentaxuser]

Intermittent agitation lets shadows develop more than highlights because highlight-development is slowed down due to exhaustion.
Rotary develops both shadows and highlights at the same rate. To prevent overdeveloping highlights, you must reduce development-time. That causes shadows to have less development. That causes film speed (EI) to drop. To compensate for that, you need to expose a little more.

Mark

Mark, I had always thought that long before the end of development time whether that be by intermittent or constant agitation the shadows have been developed but the highlights can be overdeveloped if the same time is used for constant agitation as is used for intermittent.

I wonder why most other makers of film and chemicals such as Kodak and Ilford say that constant agitation requires less development time? It would seem that only one of the two recommendations can be correct
Do you follow this Adox recommendation when using constant agitation at a constant temperature and if so what exposure compensation do you apply?

Radost, can I ask what the full source of this information?

Thanks both

pentaxuser

 

[Andrew O'Neill]

My EI doesn't change for either rotary or intermittent agitation... only the development time changes.

 

[Radost]

Mark, I had always thought that long before the end of development time whether that be by intermittent or constant agitation the shadows have been developed but the highlights can be overdeveloped if the same time is used for constant agitation as is used for intermittent.

I wonder why most other makers of film and chemicals such as Kodak and Ilford say that constant agitation requires less development time? It would see that only one of the two recommendations can be correct
Do you follow this Adox recommendation when using constant agitation at a constant temperature and if so what exposure compensation do you apply?

Radost, can I ask what the full source of this information?

Thanks both

pentaxuser

Adox website:

The best things in life are analog | FILM PROCESSING TIPS

www.adox.de

 

[Radost]

Intermittent agitation lets shadows develop more than highlights because highlight-development is slowed down due to exhaustion.
Rotary develops both shadows and highlights at the same rate. To prevent overdeveloping highlights, you must reduce development-time. That causes shadows to have less development. That causes film speed (EI) to drop. To compensate for that, you need to expose a little more.

Mark

But exposing more will over expose highlight. This is very confusing

 

[mshchem]

But exposing more will over expose highlight. This is very confusing

Very confusing. Sounds like Jobo users are going to have to do testing, because I suspect that Adox hasn't.

 

[Radost]

I noticed Kodak does not decrease development for Tmax rotary. Maybe the Tubular grain is different When developed with a Jobo…

 

[Mick Fagan]

My EI doesn't change for either rotary or intermittent agitation... only the development time changes.

Agree 100% with this. I no longer rotary develop as my Jobo broke after 30 years of hard use, but the only real difference I've done since reverting back to inversion developing is the length of the time.

This is from Developing, Jacobson and Jacobson 18th revised edition, page 79. Part of the text under, "The Influence of Agitation".

Quote:

As an example of the effect of agitation on the progress of development, it may be taken that where intermittent agitation is used about 50% longer development time should be given than would be considered necessary with constant movement.

Unquote:

 

[MattKing]

But exposing more will over expose highlight. This is very confusing

Exposing more will increase negative densities in the highlight areas.
But at the same time, cutting back on development will reduce negative densities in the highlight areas - possibly more effect in the highlights than the shadows..
It is entirely possible that ADOX's target performance is a film response curve that has a bit more density in the shadows and a bit less density in the highlights.
Or possibly that ADOX's target performance is a film response curve that has a bit less density in the shadows and a bit more density in the highlights.
In either case, I would expect their recommendations reflect what their targets are.

 

[mshchem]

I noticed Kodak does not decrease development for Tmax rotary. Maybe the Tubular grain is different When developed with a Jobo…

I just follow the tables that Eastman Kodak prepared for XTOL, not only for Kodak but for a bunch of different films. XTOL was developed with machine processing in mind, not necessarily rotary, but Kodak did do the work to document how to use XTOL with the Jobo. I haven't seen anything quite like this from others.
Adox has a procedure, kind of weird, MHOFWIW.

You start at 24°C and then let the temperature drift,while maintaining ambient, ie room temperature, at 19-20°C. Seriously?

 

[Radost]

I just follow the tables that Eastman Kodak prepared for XTOL, not only for Kodak but for a bunch of different films. XTOL was developed with machine processing in mind, not necessarily rotary, but Kodak did do the work to document how to use XTOL with the Jobo. I haven't seen anything quite like this from others.
Adox has a procedure, kind of weird, MHOFWIW.

You start at 24°C and then let the temperature drift,while maintaining ambient, ie room temperature, at 19-20°C. Seriously?

What do you think about TMAX films having the same time for rotary and inversions?

 

[mshchem]

What do you think about TMAX films having the same time for rotary and inversions?

I switched to a Jobo about 7 or 8 years ago. I couldn't believe I was getting similar results to inversion, this is using XTOL. One adaption was I only use XTOL straight no dilution one shot. There's simply not room for 1:1 dilution in a 1500 series tank.

At first I was expecting high contrast, dense negatives, this simply never happened.

I shoot TMY and TMX probably 80-90% of the time, developed in XTOL per recommended times. Kodak did thousands of individual tests qualifying XTOL, probably more than any other developer.

Not sure exactly what is happening. I get great results. Before that I got great results with a Paterson tank, inversions 1:1 and replenished.

I've used Rodinal (Adox) got good results too, but not like XTOL. MHOFWIW

I just bought the 5 rolls with developer of Adox CMS 20 film, I will try it, manual tank see if I'm amazed???

 

[albada]

Mark, I had always thought that long before the end of development time whether that be by intermittent or constant agitation the shadows have been developed but the highlights can be overdeveloped if the same time is used for constant agitation as is used for intermittent.

I wonder why most other makers of film and chemicals such as Kodak and Ilford say that constant agitation requires less development time? It would see that only one of the two recommendations can be correct
Do you follow this Adox recommendation when using constant agitation at a constant temperature and if so what exposure compensation do you apply?

Radost, can I ask what the full source of this information?

Thanks both

pentaxuser

The answer is to think of the effects on the H-D curve.
1. Developing for shorter time decreases the slope of the H-D curve.
2. Rotary dev increases the slope of the H-D curve, but less so in the shadows.
If you do both, you get the same highlight slope (contrast), but less shadow contrast, which represents a lower EI, which must be compensated by exposing more. The effect can be small enough that some prior posters have noticed no EI-change. The 1/3-1/2 stop extra exposure recommended above seems too much to me, but I haven't tested this.

Mark

 

[pentaxuser]

Here's the complete ADOX section on Rotary Processing

"ROTARY DEVELOPMENT​

With JOBO processors, known for their reliable results and saving of chemistry, rotary development becomes an attractive option.

All developing times are starting values, which should be adjusted to the individual lab (thermometer, tank, agitation rhythm, water quality etc.).
The rule of thumb for converting from an inversion rhythm to a rotation rhythm is :
Decrease the developing time by 10-15%, if you rotate constantly.

With B&W films, the physical/chemical combined effects of local developer exhaustion + cool-down during a regular agitation process (especially at 24°C), leads to increased speed utilization and compensating properties of the developer.

A development where chemistry is rotated continuously and is kept at same temperature, decreases speed utilization by about 1/3rd to 1/2 stop. It is advisable to slightly overexpose b&w films, when opting for rotary processing."

​

Can anyone reconcile what appears to be a complete turn-around in two paragraphs from ADOX. Has anything been lost in translation?

It sound like only ADOX may be able to answer what still appears to be a paradox to me

pentaxuser

 

[brbo]

It sound like only ADOX may be able to answer what still appears to be a paradox to me

It's not a paradox. @albada already explained it in post #3 in slightly different language than Adox and I find his explanation as clear as Adox's and definitely not as a paradox.

 

[pentaxuser]

It's not a paradox. @albada already explained it in post #3 in slightly different language than Adox and I find his explanation as clear as Adox's and definitely not as a paradox.

OK but for my clarification can you say why Adox has said:
"The rule of thumb for converting from an inversion rhythm to a rotation rhythm is :
Decrease the developing time by 10-15%, if you rotate constantly."

Then said:
A development where chemistry is rotated continuously and is kept at same temperature, decreases speed utilization by about 1/3rd to 1/2 stop. It is advisable to slightly overexpose b&w films, when opting for rotary processing."

Is it saying that the rule of thumb is wrong for (a) its films or (b) just wrong for all films or (c) is wrong if you want the curves to be as it believes they ideally should be but seemingly Ilford and possibly Kodak and Foma ( possibly because I cannot state that either or both of those film makers do make the statement that constant agitation requires less development time) do not say

Maybe it is only me and possibly Radost that wonders why the ADOX recommendations on what to do with changing exposure when you use constant agitation seems unique to ADOX

Oh and I might be wrong but Mick Fagan and Andrew O'Neill seem to suggest that their experiences may also "fly in the face" of what ADOX is saying

Thanks

pentaxuser

 

[brbo]

OK but for my clarification can you say why Adox has said:

I, obviously, cannot say why Adox say anything that they say.

Yes, Kodak's starting times for rotary and small tank processing are the same, but they also say:

"Follow the agitation recommendations for your processor. The design of the machine and the agitation will significantly affect the development time required to obtain optimum contrast. The times given below are starting-point recommendations. Make tests to determine if results are acceptable for your needs."


Maybe Adox actually did a couple of tests?

 

[pentaxuser]

I, obviously, cannot say why Adox say anything that they say.

Yes, Kodak's starting times for rotary and small tank processing are the same, but they also say:

"Follow the agitation recommendations for your processor. The design of the machine and the agitation will significantly affect the development time required to obtain optimum contrast. The times given below are starting-point recommendations. Make tests to determine if results are acceptable for your needs."


Maybe Adox actually did a couple of tests?

Thanks. Yes maybe. There may be a good reason why ADOX appears to say what it says but somehow I feel we may not have a full explanation

I might be wrong but until Radost's discovery of this ADOX text I cannot recall anyone here saying that if you use constant agitation then you need to "increase exposure slightly" which I take to be the ADOX recommended course of action linked to "decreases speed utilisation of a third to half a stop"

Your quote of what Kodak says seems like a "catch-all" kind of recommendation which has to be by its very nature true but from which it is impossible to draw actual concrete, usable information

Anyway I suspect this thread may have come to its inevitable "forum death"

pentaxuser

 

[MattKing]

might be wrong but until Radost's discovery of this ADOX text I cannot recall anyone here saying that if you use constant agitation then you need to "increase exposure slightly" which I take to be the ADOX recommended course of action linked to "decreases speed utilisation of a third to half a stop"

The reason you need to increase exposure isn't because of the effects of constant agitation. It is because you need to counteract one of the side effects of the steps you take to deal with those effects.
The consequences of constant agitation are increased development and contrast - particularly with the highlights.
When you seek to counteract that increased development and contrast by reducing the development time, there is what may be an unintended further consequence: reduced density, particularly in the shadows - effectively a reduction in film speed.
So to compensate for that unintended speed reduction consequence, you need to increase overall exposures.
It is not unlike when doctors prescribe one medicine to deal with the side effects of another medicine used to treat a disease.

 

[pentaxuser]

The reason you need to increase exposure isn't because of the effects of constant agitation. It is because you need to counteract one of the side effects of the steps you take to deal with those effects.
The consequences of constant agitation are increased development and contrast - particularly with the highlights.
When you seek to counteract that increased development and contrast by reducing the development time, there is what may be an unintended further consequence: reduced density, particularly in the shadows - effectively a reduction in film speed.
So to compensate for that unintended speed reduction consequence, you need to increase overall exposures.
It is not unlike when doctors prescribe one medicine to deal with the side effects of another medicine used to treat a disease.

Thanks Matt so can you link for me what you have said above to what ADOX has said? Its text really doesn't even seem to touch on this. It simply seem to state that constant agitation at a constant temperature results in the need to increase exposure with no explanation. What you have said above would seem to apply to every case of using constant agitation, is this correct? Is this something that can't be corrected by applying the correct amount of reduction to the development time used for intermittent agitation or are you saying that there is this unintended consequence that accompanies constant agitation which can be only compensated by increasing overall exposures?

Can I also ask what the link is between what you have said above and your # 11 which seems to suggest that it might be connected with ADOX having different targets

For the benefit of anyone still following this thread but can't remember what you said in #11 here it is

"Exposing more will increase negative densities in the highlight areas.
But at the same time, cutting back on development will reduce negative densities in the highlight areas - possibly more effect in the highlights than the shadows..
It is entirely possible that ADOX's target performance is a film response curve that has a bit more density in the shadows and a bit less density in the highlights.
Or possibly that ADOX's target performance is a film response curve that has a bit less density in the shadows and a bit more density in the highlights.
In either case, I would expect their recommendations reflect what their targets are"

Thanks

pentaxuser

 

[Mick Fagan]

Pentax user, it appears that you are baffled as to why I haven't needed to change my initial in camera film exposure when doing constant rotary agitation versus intermittent agitation using an inversion technique. That was/is a fair question, and something I didn't think too much about in my initial reply.

I use a lower ASA rating than what is written on the outside of the film container packaging for every film I use. This is obtained by testing my exposure and developing technique from the get go. So in effect, I have already given the film more exposure to ensure that as far as I'm concerned, I am starting with correct exposure and development.

Over the decades I have found that once you obtain correct exposure and film developing parameters, that are correct for your shutter errors and film developing system, then the only change is the developing time difference required when switching from constant agitation to intermittent agitation.

In 35mm photography this is easy, the camera only has one shutter, with my 4x5" format cameras it is slightly harder, each of my seven lenses is equipped with it's unique shutter and there are some quite large differences between them.

 

[MattKing]

pentaxuser:
There is no single "correct" answer - no single right, with all the rest being wrong. But there are clear tendencies, and reasonably narrow ranges for acceptability.
ADOX has provided recommendations for how to compensate for the changes between two different types of agitation. They are just that - recommendations, and they will be founded on their preferences.
Even with those recommendations applied, the results will be vey similar, but not identical.
The differences will probably be minor though.
And the effect of those changes, as well as the effect of the recommended compensation steps, will vary from film type to film type, and developer type to developer type.
But the variances will be relatively small - the sort of thing one might either leave in place, or make small adjustments for - essentially the same as cooks who "season to taste".
Mick Fagan posted above about his choice, when switching to continuous agitation, to not increase exposure more than he already increased that exposure. I would point out that by already increasing exposure with non-continuous agitation, he had already chosen to employ a differently shaped part of the characteristic curve than someone who chose to give the film less exposure and non-continuous agitation. It may be that for that reason alone, the necessary compensation for the change in agitation would have been different than if his starting point was different. It is also possible, of course, that he simply preferred the results after the change in agitation combined with a reduction in time.

 

[pentaxuser]

Pentax user, it appears that you are baffled as to why I haven't needed to change my initial in camera film exposure when doing constant rotary agitation versus intermittent agitation using an inversion technique. That was/is a fair question, and something I didn't think too much about in my initial reply.

I use a lower ASA rating than what is written on the outside of the film container packaging for every film I use. This is obtained by testing my exposure and developing technique from the get go. So in effect, I have already given the film more exposure to ensure that as far as I'm concerned, I am starting with correct exposure and development.

Over the decades I have found that once you obtain correct exposure and film developing parameters, that are correct for your shutter errors and film developing system, then the only change is the developing time difference required when switching from constant agitation to intermittent agitation.

In 35mm photography this is easy, the camera only has one shutter, with my 4x5" format cameras it is slightly harder, each of my seven lenses is equipped with it's unique shutter and there are some quite large differences between them.

Mick I hadn't realised that you had interpreted my bafflement in this way. It is not so much that you haven't found the need to change times when changing as the fact that ADOX appears to be suggesting that with constant agitation you need to increase the exposure time for the film to compensate as it were for constant agitation, having said in two paragraphs above this statement that the rule of thumb is to decrease development time by 10-15% when using constant agitation.

This is the consensus approach which Adox states. Could it really be saying that while this is the consensus approach this is the wrong approach and will not by itself result in the same negative as using the "correct" time for intermittent agitation?

If so I wonder why it has not taken the trouble to explain this in more detail as it flies in the face of the rule of thumb that other film makers seem to follow


Like many others Mick you have found, as you have said, that your film speed differs from the rated film speed and I understand this. I equally understand why you may use a development time that differs from that stated by the film maker However Adox seems to be saying that no matter what your development time or personal film speed is with intermittent agitation you will have to change your exposure time for your shots if you decide to change from intermittent agitation to constant as I said above.

Matt gave two explanations of this. The first in his #11 was what Adox was recommending needed to be done to achieve its own "correct" H&D curve i.e its meeting its own targets. The second explanation was the one centering around the unintended consequences of switching to constant agitation

Again both might be true and Matt has taken the trouble to explain both but what troubles me is that Adox has not taken any trouble to explain this at all It just leaves me uneasy about whether there is not something we are not being told by Adox

It just seem strange that a major company has not chosen to expand on its suggestion to do something which it knows will appear to fly in the face of conventional wisdom about what a user does when changing from intermittent to constant agitation

pentaxuser