That's color film, not B&W. No B&W films have such a layer, so far as I know.
They also incorporate other anti-halation tools - besides that base.
The layer diagrams I have only deal with the colour negative films - and Kodak ones at that - but those show AH layer between the bottom light sensitive emulsion layers and the subbing layer that sits directly on the base.
That's color film, not B&W. No B&W films have such a layer, so far as I know.
His charts are no longer available (deleted account?)
The general assessment is that Kentmere/Kentmere PAN films are:
The result of the silver and grain differences is slightly lower resolution.
Several of these assessments are impossible to substantiate with the kind of information the likes of us have access to. I'm referring to the degree of hardening, silver content and anti-halation measures (qualitative and quantitative). Other factors are often assessed on the basis of very shaky empirical testing and interpretation of the outcome of such tests.
I don't see any theoretical or physical basis for this claim. It also ignores the (by contrast) highly relevant difference in grain structure/aspect ratio.
in terms of how softened it is by permanganate bleaches or damaged by peroxide bleaches
For the record, I like and use both Kentmere 100 and 400 PAN films and will continue to do so.
Even back years ago, when we could still get Efke films, I remember a lot of the web verbiage describing them as "Old style high silver thin emulsions."I'm somewhat allergic to the 'silver content' argument because it generally isn't rooted in factual information on how silver load affects imaging behavior, and all too often involves implied normative judgement on the desirability of high silver content. Such an advantage has never been demonstrated to exist.
This may be one of the aspects that affects permanganate, but peroxide bleach generates bubbles which have to pass out through the emulsion. In my experience the films aimed at reversal, which I surmise to be more hardened, fair worse in peroxide because rather than allowing the bubbles to release, they tear out through the gelatin. I found this to be true for Fomapan R100 and for ADOX Scala 160 and for old Agfa Scala 200. By contrast, most other films are not as damaged by peroxide bleaches. Films considered to be "soft" like Fomapan 400 and 200 do quite well in peroxide reversal. Does it prove anything definitively? No. But it's aligned with my other experience and what I've seen from other people.This says mostly something about the quality of the subbing procedure and thus the adhesion of the emulsion to the film base. It's not really indicative of the hardening of the emulsion as such. Subbing approaches have improved dramatically at the main manufacturers (Kodak, Fuji, Harman) even since the 1990s. Smaller manufacturers may still lag behind on this.
"High silver content" either implies a thicker emulsion layer, finer grained crystals such that less space is "wasted" in between them in the same thickness of gelatin, or a different crystalline structure that allows them to be packed more tightly. I think we can safely assume that any of those affect the image output. None of that implies that you will get a definitively "better" output from higher silver conten. But in any of those cases, the ability to catch more of the light in the same surface area is going to be improved. Whether or not those image centers are reachable by developer is another story.I'm somewhat allergic to the 'silver content' argument because it generally isn't rooted in factual information on how silver load affects imaging behavior, and all too often involves implied normative judgement on the desirability of high silver content. Such an advantage has never been demonstrated to exist.
I've shot both Kentmere 400 (branded as Rollei RPX back then) and HP5+. I found the differences subtle to the advantage of the latter in terms of retention of shadow detail and graininess. It's been ages since I shot any Delta, so I couldn't comment. I wouldn't on the basis of my qualitative observations dare draw any conclusion in terms of hard criteria such as resolution.
peroxide bleach generates bubbles which have to pass out through the emulsion
"High silver content" either implies a thicker emulsion layer
Good luck with that!
Most questions I have submitted to this community have resulted in a considerable amount of noise and conflicting opinions. It may be that I did get one or two authoritative answers, but it was hard to identify those among all the noise.
I think one reason there are so many conflicting opinions is because everyone exposes different, develops different, and likes different results. If two opinions conflict with each other, it doesn't necessarily mean one is right and the other is wrong. Opinions are not facts. When it comes to opinions, there is no authoritative answer.
There are patents showing it as background information about why the proposed peroxide bleach was unique. Not for this film, and I don't have them at my fingertips, but I read through tens of these patents a few years back when working on the peroxide/citric acid/EDTA bleach I published, and this failure mode is a fairly-well-researched fact. The gelatin is torn to a lesser or greater extent by the formation of bubbles inside it. It is not torn off of the substrate.I have severe doubts about the correctness of this technical assessment of the failure mode you're seeing with certain reversal processes. There are many ways in which a gelatin layer can disintegrate and/or peel away from the base it's adhered to.
Ok, I am not sure what we're discussing at this point, honestly. The OP asked how they differed. If you'd like to characterize some of that differently, please feel fee to contribute how you would practically characterize it for someone wanting to shoot these films. Having more than one opinion of stated summary is certainly not unhelpful.Gelatin layer thickness is yet another parameter. We do agree that crystal geometry and orientation have an effect, and tabular grain emulsions exploit this property. It's one of several factors that breaks the correlation between silver content and imaging properties. Silver content as such says nothing.
@relistan @koraks there is evidence from some Agfa patent materials etc that they added further gelatin tanning agents to subbing layers etc in materials that were potentially going to be subjected to processes like B&W reversal (and added both gelatin swell agents and gelatin swell control components in their first developer) - which can (in their more modern forms) probably subject emulsions to greater stresses than C-41 or E-6. That cost would only be worth the expenditure by Harman (or Kodak for that matter) if a much more significant amount of their emulsions were being subjected to prolonged bleach baths in B&W reversal.
It's also probably not impossible that the genesis of the Kentmere films relates to the newer rapid-mixing emulsion plant built for Delta etc (and which the paper emulsions have moved to) - it will be able to manufacture whatever crystal form you need for a particular emulsion outcome, but may have a greater familial resemblance to aspects of Delta than the FP/HP family (more tightly controlled monodispersity of each discrete emulsion probably being a significant part of it). The same plant probably also allows for a greater degree of cost control & estimation of what certain performance boosting components would have relative to cost/ performance. They were probably particularly interested in how readily FP/HP type emulsions could be translated to the new plant.
If you'd like to characterize some of that differently
However, you pretty much get the beautiful spectral sensitivity and response curves of Delta.
Hope it helps
This was from the charts I referred to from @aparat in my first post.What's the source of this information please? Firstly, which Delta are we talking about? The spectral sensitivity of Delta 400 is different from that of Delta 100.
So, it appears that "Camerarabbit", who posted the question, isn't paying any attention to this discussion, so bear that in mind.
If he is no longer paying any attention and that may be the case then we need to ask ourselves why if the prime purpose of the forum is to provide answers to questions asked and answers that are commensurate with the OP's level of knowledge
It's also probably not impossible
Can I assume you're suggesting Kentmere 400 has the spectral sensitivity of Delta 400
Lower silver content than FP4+/HP5+/Delta films
More in the sense of some aspects of perceptual image structure behaviour than colour sensitivity.
The purpose of the forum is to provide a place for discussion relating to photography.
There is a side purpose as well - it provides a forum for sharing some photography.
And for some, there is a marketplace add-on.
A lot of things get learned. A lot of questions are answered. And a lot of discussion happens.
We try to keep threads to the general subject raised when the thread is started, but thread expansion or "drilling down" happens.
Otherwise we wouldn't get the benefit of the rather wonderfully vague
"We" do, though. Often, OP comes back and asks follow-up questions.Just a pity that at times we don't drill down a little more into what the OP might want or need to know first
Thanks Matt, that was largely the answer I was expecting. Just a pity that at times we don't drill down a little more into what the OP might want or need to know first
pentaxuser
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