Stupid question about agitation

[cambolt]

Greetings from the world of DSLRs😀
This may sound really stupid to some of you who have grown up with film, but I am in doubt about a couple of aspects regarding B+W film processing:
1) If an information sheet tells me to agitate for the first 10 seconds of every minute, does this mean agitate 10 times, or can I agitate say 3 times as long as the total time agitating is 10 seconds? And if the info sheet says agitate 3 times per minute, does this mean I could take as long as I wanted to do the 3 agitation in the minute, or again is it 3 agitations at 1 second each?

2) I have a photax paterson style tank, like the one http://i.ebayimg.com/15/!CF4C4uwBmk~$(KGrHqEOKjsE0PnUfgcsBNWePsBH5w~~_35.JPG I have noticed that there is a circular button in the middle of the lid. It seems to be some sort of air valve. Does anyone know what this is for?

Sorry if I'm being a little confusing, I am like that sometimes.

Thanks

 

[ChrisN]

Agitate for 10 seconds. If you can invert three or four times in that 10 seconds without getting too violent, go for it! But three or four inversions in that 10 (or 15) seconds is the norm. Then let the tank sit still for the rest of the minute.

 

[cambolt]

Thanks for the reply.
So if I was to agitate 10 times in that 10 seconds, would there be any detrimental effects? That's what I've been doing for the past few rolls 😱

 

[Chriscrawfordphoto]

Thanks for the reply.
So if I was to agitate 10 times in that 10 seconds, would there be any detrimental effects? That's what I've been doing for the past few rolls 😱

Yes, over-agitation increases grain considerably and it affects contrast too, raising it.

 

[Roger Hicks]

Thanks for the reply.
So if I was to agitate 10 times in that 10 seconds, would there be any detrimental effects? That's what I've been doing for the past few rolls 😱

None to speak of. My experience differs significantly from Chris's here. All you're doing is making sure that the surface is regularly bathed with fresh developer, and you can't get more developer into the film just by shaking hard.

I would be astonished if anyone, in a blind test, could tell from the enlargements which films were shaken hard and which were inverted gently.

Yes, constant agitation gives slightly more true speed and (unsurprisingly, therefore) slightly bigger grain. But that's 60 out of 60, not 10 out of 60. If you develop for the same time as with intermittent agitation, and agitate constantly (60 seconds out of 60) you'll get more contrast, but even then you can easily go down to ISO contrast (with more true speed, too) just by cutting development time to compensate.

This is not just my opinion and experience. It's that of Ilford's experts too, and none of the books by major authorities on the subject (Haist, Glafkides, Clerc, Neblette, John & Field, Coote) makes any warning whatsoever about excessive agitation. Worrying about it is mostly a product of the internet, combined with people seeing what they want to see.

Cheers,

R.

 

[Chriscrawfordphoto]

Roger,

It is NOT a product of the internet. This has been advice taught to students and repeated in texts on developing for a century. The chemists you quote don't mention it because they don't care. They aren't developing film to make art. They're developing to make H&D Curves to test speed and contrast.

I've done tests and it does increase grain. How much depends on the film and the developer, some are more sensitive than others. The print size makes a difference too; you won't see the difference in a 5x7. You will in an 11x14 from a 35mm neg. I know, I regularly make them. Constant agitation also increases contrast, which is easy enough to compensate by using a shorter developing time. That's why manufacturers give shorter times for processing in rotary processors (Jobo).

Something else to watch for is evenness of developing. Under-agitating has caused me problems with the top and bottom edges of 35mm frames developing more than the middle. Some claim overagitating causes that too, but i have not seen it.

Basically, the OP needs to find an agitation system that works for him and then stick to it rigorously for repeatable, consistent results. Nothing wring with constant agitating if you reduce dev. time to compensate for the change in contrast (shorter Developing time reduces grain, so that may be why the grain difference is not that great for those who have standardized on constant agitation....but if you're used to using intermittent agitation and you accidently agitate too much, you'll get results that look grainier and contrastier. If the OP really wants to do continuous agitation, he should look for a Jobo system. Constantly shaking a hand tank full of chemicals makes your arms sore!

 

[Roger Hicks]

Roger,

It is NOT a product of the internet. This has been advice taught to students and repeated in texts on developing for a century. The chemists you quote don't mention it because they don't care. They aren't developing film to make art. They're developing to make H&D Curves to test speed and contrast.

I've done tests and it does increase grain. How much depends on the film and the developer, some are more sensitive than others. The print size makes a difference too; you won't see the difference in a 5x7. You will in an 11x14 from a 35mm neg. I know, I regularly make them. Constant agitation also increases contrast, which is easy enough to compensate by using a shorter developing time. That's why manufacturers give shorter times for processing in rotary processors (Jobo).

Something else to watch for is evenness of developing. Under-agitating has caused me problems with the top and bottom edges of 35mm frames developing more than the middle. Some claim overagitating causes that too, but i have not seen it.

Basically, the OP needs to find an agitation system that works for him and then stick to it rigorously for repeatable, consistent results. Nothing wring with constant agitating if you reduce dev. time to compensate for the change in contrast (shorter Developing time reduces grain, so that may be why the grain difference is not that great for those who have standardized on constant agitation....but if you're used to using intermittent agitation and you accidently agitate too much, you'll get results that look grainier and contrastier. If the OP really wants to do continuous agitation, he should look for a Jobo system. Constantly shaking a hand tank full of chemicals makes your arms sore!

Dear Chris,

Grant Haist might disagree with you about creating art. So might some of the others I have spoken to: quite a number of people who work for major manufacturers are enthusiastic photographers as well as emulsion chemists or engineers. It is a fair criticism that much of the published research is based on larger formats than 35mm, where grain matters less, but contrast is a red herring in any format as it can always be reduced via less development (shorter time, lower temperature, weaker developer, less agitation).

Of course overdevelopment will give more contrast and bigger grain, but as you and I both point out, developing for the same time with constant agitation is indeed a form of overdevelopment. You are of course absolutely right that consistency is the important thing, but I still dispute very strongly that there will be a difference that anyone could see in a blind test if the agitation were a constant 10 seconds per minute, regardless of whether there were three agitations or ten in that ten seconds. This is, after all, what he was asking about, not constant agitation.

Cheers,

R.

 

[Tim Gray]

Over agitation can produce surge marks. However, I don't know how much you need to over agitate. 10 seconds of agitation every minute is most likely not going to do that.

When in doubt, don't listen to all of us that have formed opinions based on *our* practices. I'm sure Roger or Chris's single inversion is different then mine. In fact reading what Chris wrote, I'm positive it is. For example, I do 5 inversions in roughly 5 seconds every 30 seconds.

Go to the source, Kodak or Ilford, and use the directions they supply. Once you start doing it some you can adjust to taste. The important thing is being consistent. Do it the same way every time.

http://www.kodak.com/global/en/professional/support/techPubs/aj3/aj3.pdf
http://www.ilfordphoto.com/Webfiles/200629163442455.pdf

 

[Fotohuis]

Yes, consistency is the best advice.

But depending of type developer you can get some differences.
In general high acutance developers give less grain when doing gentle and a minimum of agitation.

I am using two developing "robots":

Heiland TAS inverse processing
Jobo CPA-2 continuous rotary development.

Looking at 35mm and a high acutance developer like Rodinal then the difference is visible. You will loose acutance / sharpness in rotary and it generate a bit more grain.
But for some other developers (AM74, CG-512) I would not see in a regular print a real difference.
And now we are talking about extreme different developing methods.

 

[robklurfield]

This is a good debate. Two smart guys expressing some deeply held and somewhat (on the surface) contrary views with great respect for each other and no vituperative invectives being hurled about. I am impressed, Chris and Roger. And, simultaneously edified and confused. Good show. I look forward to the next installment. If I keep listening to both you, I'm pretty sure I can learn more and get better at this, so do keep it up!🙂

 

[ChrisP]

Increase Speed?

Increase Speed?

Yes, constant agitation gives slightly more true speed and (unsurprisingly,
R.

Does constant really increase speed? If so by how much (approximately)? Are we talking like a third of a stop or way down there like a tenth?

I'm new to film and haven't heard about this before (and I can never get enough light).

 

[Tim Gray]

Does constant really increase speed? If so by how much (approximately)? Are we talking like a third of a stop or way down there like a tenth?

I'm new to film and haven't heard about this before (and I can never get enough light).

I'm not disagreeing with Roger - I'm sure there constant agitation can increase real speed.

Changing agitation can change speed. I've heard it the other way around though - less agitation increases speed. More agitation increase contrast. 'Speed' is defined here by shadow density, not mid-tone and highlight density.

The way I've read it explained is that agitation replenishes the developer as it gets exhausted near the film. Developer develops the film quicker (and exhausts quicker) in areas of higher density (more exposure) since there are more exposed grains to develop. So if you agitate a lot, you are constantly replacing exhausted developer with fresh developer in these areas, causing them to get developed to higher densities. This increases contrast since the areas of low densities (shadows) don't benefit as much from the fresh developer - their exposed grains are few and far between, so they exhaust the developer at a much slower rate.

Conversely, if you agitate less, the developer exhausts in the high exposure areas and development rate slows down, limited by the lack of active developer. The shadow areas don't exhaust their developer as much, so they just keep developing and increasing in density. This ultimately can reduce contrast as the shadows build density relative to the slower growing mid-tones/highlights.

From what I understand, the above is more apparent with drastic changes in agitation. We're talking about stand/semi-stand development vs. normal agitation, not 7 seconds of agitation every minute compared to 9 seconds.

Keep in mind that what I described above is really talking about speed = shadow tones. If you want to shoot Tri-X at 3200-6400 and don't give a crap about your shadows, you just want super high contrast, normal agitation and an extended development time might give you what you want. Many will say you increased your 'speed', but in reality the primary result is that you've increased the contrast of the negative (increase the density of the highlights and mid-tones).

 

[Roger Hicks]

Does constant really increase speed? If so by how much (approximately)? Are we talking like a third of a stop or way down there like a tenth?

I'm new to film and haven't heard about this before (and I can never get enough light).

Yes, but not by much. Even 1/3 stop would be remarkable. That's true ISO speed, defined as shadow detail at ISO contrast. Most of these differences are pretty small. As Tim says, you need fairly gross differences in agitation regime to affect speed or grain by a great deal. And, as he also says, everyone's agitation is different. I normally do 7 inversion cycles in 10 seconds.

Chris Crawford and I aren't really disagreeing. Agitation does affect development. Where we differ is how much difference you will see between 4 and 10 inversions in 10 seconds. And, as Fotohuis points out, a lot depends on the developer. Acutance developers work best with the minimum amount of agitation you can get away with.

Cheers,

R.

 

[tlitody]

for constant agitation read "increased development". More development always increases speed to a point. Just think about pushing film. But pushing film through extra development increases film contrast too. So you makes your choice and pays your money. Either you go for the extra speed and accept the higher contrast or you reduce your time to keep the contrast normal but at the cost of not getting as much speed.
As already stated the idea that constant agitation increases contrast cannot be taken alone as the other factors of time, temp and dilution have to be considered too. Change just one factor and it will have an effect one way or the other. But it can always be compensated for by changing one of the other factors in the opposite direction until you get the balance you want.

 

[Peter S]

The fun thing with developing your own film is that you can experiment. Just do one with very gentle agitation and one with more agressive agitation. Both methods should give you printable negatives and you can see for yourself what you think of grain/contrast. Of course the films have to contain more or less similar exposures (I mean shot in more or less the same type of light).

With my particular film/developer combination (Tri-x + Rodinal 1:50) I saw more grain when agitating with a cocktail shaker technique, but maybe other film/developer combinations are less senisitive. I also think that if you agitate too wildly you run the risk of getting bubbles in your developer and that can lead to uneven development.

In any case it is fun and all of us here -even when we respectfully disagree- are here to help you with all your questions. It is a good bunch here.

The "valve" is to let air escape after you have put the lid on the tank, it helps against leaking when you agitate.

 

[Dana B.]

I know this may prove shocking to some, but I don't invert. Instead, I was taught to slowly roll the stainless processing tank for 10 seconds at the top of each minute, then give it a couple of taps to shake loose the bubbles. (For fixer, I start with 30 seconds, then revert to the normal 10 secs. per minute). Does anyone else roll their cannister back and forth along the countertop?

 

[cambolt]

Thank you all for your replies.
This has certainly turned into a rather interesting debate...
I have been using my "vigorous" agitation method with ID-11 so far, and haven't seen crazy contrast or grain yet.
With this "valve" on the top of my tank, should I be pressing this as I agitate?

Thanks again

 

[Michael Markey]

Yes thanks for the debate.
I must admit that my foray into development has been a disaster on the whole.
I have felt compelled to over agitate for some reason and have blamed that for the poor results.
Stewart (Sparrow) suggested that I go for longer development times and that seems to have solved the problem.

 

[Roger Hicks]

The fun thing with developing your own film is that you can experiment. Just do one with very gentle agitation and one with more agressive agitation. Both methods should give you printable negatives and you can see for yourself what you think of grain/contrast. Of course the films have to contain more or less similar exposures (I mean shot in more or less the same type of light).

Dear Peter,

This is easily the best answer so far!

Cheers,

R.

 

[Peter S]

Thanks Roger.

Cambolt, I don't know your type of tank, but you usually only press it once. You pour in the liquid, tighten the lid and because very often there is overpressure in the tank (and that usually causes the leaking) you either press the valve or - as I do with my tank - lift a small corner of the lid, let the air escape (your hear a hissing sound) and then tighten the lid for a second time.