Nonsense.
There is nothing else that can cause that specific effect.
I'm not following you. Agitation breaks up and disperses the bromide. That's why you agitate. I do not use Rodinal, but I have used it in the distant past. I use FX-39 now.
Here's your quote that I used in #104:
Augustus Caesar said:
The differences in the emulsions are not a factor. The fact that the bromide can't move when the glass plate is perfectly horizontal prevents the streaks. I'm sure that some agitation was used even in these cases. I use gentle agitation, two inversions once per minute.
There appears to be a contradiction between sentence 2 and sentences 3&4 . If you avoid streaks( I assume you are referring to bromide streaks or what is commonly called " bromide drag" ) by a perfectly horizontal glass plate then any movement in the plate or presumably sheet by even a little agitation risks streaks but this is what you then say you so to avoid streaks
pentaxuser
OK, let me explain: Streaks in stand development of roll films held vertically are caused by strongly differential release of bromide in adjacent regions, such as a negative of a polka-dot pattern.I wouldn't go so far. If you think about it, it's not so different from how a JOBO expert tank works for developing 4x5 or 5x7 sheets. The solution pours into and out of each sheet compartment as the drum rotates. It works because some developer remains on the emulsion for the portion of the rotation when it is not immersed. Perhaps the same applies to draining and refilling the tank he describes.
His name was Kurt Jacobsohn, publishing under the name C.I. Jacobson. It was the Getty Library which called the published name a pseudonym. No harshness was intended.
If I seemed harsh, it is because the Internet has become a sewer with trolls publishing misinformation under pseudonyms. Augustus Caesar shows up, posts unsupported and at times counterintuitive remarks as facts that fly in the face of many photographers' experiences; and when asked to support his remarks, he cites a 75-year-old book without any effort to explain the basis of his remarks. Mr. Caesar might be Saint Ansel Ouiji-ing in from the beyond and perhaps we should all be grateful to him for sharing his wisdom posthumously. But his cavalier approach to it just clutters up a website that should be devoted, at least in part, to preserving trustworthy information about analog processes for future generations.
The slow movement (caused by gravity) of concentrated bromide on a vertical film surface is what causes streaks in "stand development", if the developer is not given regular, frequent, gentle agitation. On a perfectly level glass plate, no movement takes place because gravity cannot move the bromide: the glass plate supports it. There will be some very minor movement of the solution due to small vibrations from the environment, but the result will not be any significant streaking.
Ziff waves, no doubt. ;-)
Come on: Hydrodynamics is much more complicated than gravity pulling bromides down the film. There are just too many forces at work -- e.g., buoyancy, density, temperature, hydrophilia, electrochemical forces, to name but a few -- to reduce this to a simple notion that gravity streaks film by pulling bromides down.
If you have a proper background in physics and hydrodynamics, and you have put in the time to study how these particular substances act in particular developer solutions, then please tell and I will stand corrected.
OK, let me explain: Streaks in stand development of roll films held vertically are caused by strongly differential release of bromide in adjacent regions, such as a negative of a polka-dot pattern.
On the other hand, a negative of a grey, featureless surface will likely not display streaks, because all of the bromide across the surface is being released at about the same amount. In the case of glass plates held perfectly horizontal, gravity cannot move the bromide: it stays where it forms. Thus, no streaks can form. So, those practitioners who do not experience streaks are likely making negatives that do not have vastly different areas of exposure in close proximity.
Again, your "explanation" is just another ipse dixit. You give us no basis to credit it. And it runs counter to accumulated experience of many photographers (mine included) who do not observe the phenomenon as you describe it. I can show you a thousand sheets of 120 roll film negatives, all semistand-processed in vertical reels, that show no bromide drag anywhere. That is not "luck," as you put it earlier. that is a repeatable process. Please feel free to have your centurion drive your chariot down to North Carolina, and I will be happy to demonstrate.
In post 132, you say: "The phenomenon is well-documented. Read Jacobsen and Jacobsen." [sic.] Since you are the one positing a counterintuitive and apparently-incorrect position, you might find your views better-received here if you would quote to us the passages from Mr. Jacobsohn's treatise that you think support your views. At least then we could have a meaningful discussion of the subject.
What is "counter-intuitive", pray tell?
There are many effects caused by bromide release in photographic development. Some of them have different names, but all are related. One of them causes negatives of solid areas of uniform brightness to be less dense towards the center. Mackie lines and the Eberhard Effect are just two of these.
No one disagrees with the general proposition that bromide drag, or Mackie Lines, or the Eberhard Effect exists. The problem comes when you assert without support that semistand development only works for a few "lucky" photographers because these effects cannot be avoided because of gravity's operation on bromides. I don't see any disciplined text that draws that conclusion from the observed phenomena. And your conclusion is belied by the collective experiences of many top-drawer photographers.
I will stop beating a dead emperor for now and trust that future readers will judge for themselves whether your assertions have merit.
Nonsense.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?