+1
What I'm saying is if you run a tightly controlled process, and then run expired film through it, the entire imaging chain is still out of control. I don't really see the benefit of going through the lengths of test strips and densitometry for a development process if you end up running expired film through it anyway.
Thanks. I may have misunderstood what you said. I had wrongly thought that something had changed on one occasion with your Jobo and that the change had caused over agitation on that one occasion.I only do rotary processing these days so I am not able to compare with results from intermittent agitation. Sorry about that. I can only tell that the rotary processing (constant drum rotation) seems to cause over oxidation to the developer. You can see bubbles, lots of it, when the developer is poured out of the JOBO drum. The bubble obviously contains lots of oxygen.
You can see bubbles, lots of it, when the developer is poured out of the JOBO drum. The bubble obviously contains lots of oxygen.
There is no such thing as 'over-agitation' in C41 processing. The process is designed for constant agitation and it's by definition impossible to agitate more than all the time!
One would think so. But take a look at Z-131 page 5-31, where Kodak plots RGB density variations caused by under/over agitation. If it made to the process control section of the C-41 process manual, it must be a thing!
Koraks, please show where Kodak has ever said C-41 was designed for constant agitation. Their own literature describes processes that use intermittent agitation,
and PE said they always used intermittent agitation in testing at Kodak. Constant can be used, if it is controlled properly.
Koraks, please show where Kodak has ever said C-41 was designed for constant agitation.
Very much so. Please read back what I wrote; you'll notice we agree on scanning and optical printing, and the color corrections needing to be done in both workflows.
What I wanted to caution against, is an often-heard mantra: "this is what I get straight from the scanner and it looks pretty good, so my film and processing are very good." That logic doesn't add up in many ways. The opposite also doesn't work: "without doing adjustments to the image I get from the scanner, the result is crap, so there's something wrong with my film processing". The simple truth is that in a typical consumer scanning setup, what you get from the scanner says nothing about the quality of the film or the processing. One can get decent scans from horribly compromised film and processing (ECN2 film cross-processed in C41 developer is a popular one these days) and vice versa.
All these told me the scanner scanned the 3 frames of film faithfully.
Kodak did advise not to replenish the developer used in rotary processors. That seems to say the developer is too oxidized and can not be replenished normally.
Kodak did advise not to replenish the developer used in rotary processors. That seems to say the developer is too oxidized and can not be replenished normally.
Here's a question that has occurred to me. If inversion is OK i.e produces the same negative to the same quality that continuous rotary processing does then is there an appreciable range of agitation that will produce the same negative. It would seem like it.Koraks, again, both types of agitation can be and are used so I don't see how your statement is true that C-41 was designed for continuous agitation. It is misleading.
C-41 is designed for a standard development time of 3' 15''. The type as well as rate of agitation does make a difference, therefore results are controlled by properly adjusting agitation rates for each during development time.Is there something about colour negs developed in C41 that makes no difference to the result whether you invert or continuously rotate?
Emphasis on "normally".
Whenever you read anything like a colour datasheet from Kodak, it is important to remember that it is targeted toward a commercial lab audience.
If Kodak was unable to make recommendations for how to replenish developer used in a variety of rotary processors that would result in relatively simply maintained consistent results, they would recommend against such use.
The recommendation against may be related to oxidation, or variability between the available options, or other factors that might come to mind.
Yes, if the drum is fully filled the oxidation of the developer may be minimized to a degree similar to dip and dunlk processors.It may be that using a rotary processor with tanks that are closer to being filled may solve the problem. It may be that standardizing on one type of tank and reel may solve the problem. The rotation speed chosen may be critical - or???
The question here is if moving images from one medium (such as a negative) to another (such as a digital file viewable on a monitor) can be done without the image information being altered. It is easy to say a scanner, a technology based tool, induces inconsistency from the image move transition. Of course it does. However, the 3 shot example I mentioned and the scans was to describe that it looks my scanner did not correct (automatically) the under and over exposed films. Their histograms are showing where they should reasonably be. If the scanner software did automatically some adjustment to be kind to the users the histogram will reveal that. It is a mystery if colors are altered and users have no idea what alteration had happened is purely caused by the scanner software. Keep in mind the gamut (color space) of a negative and a monitor are very different. There must be a very complicated algorithm in the scanner design engineer's mind to deal with the media difference. But whatever it is there is not an intention to make adjustment to alter the image data in my scanner. I did not mention the gamut of the Scanner's CCD,did I? Thank about if it is factored in. In my opinion, optical printing exists a similar media move issue. There is always differences between before and after the move transaction of the image data.'Faithful' is a very fickle concept in the context of scanning color negatives. Faithful to what? You point out that three differently exposed frames show expected differences in value distribution. But a truly 'faitful' scan of a color negative would be an overall brown-orange image with a relatively low-contrast and inverted color image on it. You appear to refer to inverted scans that look natural at least to some degree, and this implies that some kind of color correction has taken place. Photograph a color negative and invert it without any adjustment, and the image will be far from natural looking. The scanner (and especially its accompanying software) makes some kind of judgement based on image content as to what is supposed to be natural, usually based on things like assumptions on density distributions based on statistical analysis. It's an approximation, and the vast majority of scanners are demonstrably inconsistent - which is a good thing, because this makes them far more user-friendly than if they would have interpreted every negative according to some arbitrarily chosen gold standard.
Oxidation prevention by HAS is static. Agitation is dynamic. More agitation causes more oxidation.Think about it - if there were an absolute reference, what should it be? Fresh Kodak Gold 200? Or Ektar 100? Or something else? Then what happens if the user scans a strip of expired film with higher fog? They should get washed out images with reduced shadow densities in the positive, due to the high b+f in the negative. You appear to not get that with your expired film, which is an immediate sign that your scanner, too (like virtually all others) does an 'autocorrect' on image data.
All this automatic adjustment isn't such a problem, though. The only implication is that a scanner, unless it's run in a color-calibrated mode that disables all automatic adjustments, which is likely impossible with most scanners, can not be used as an absolute reference for determining process quality. A film scanner is not a densitometer.
This is not just due to oxidation during development. Run the math on how much oxygen the developer could physically absorb during a development run of a few minutes and how much HAS there is in a typical C41 developer. It's impossible to use up the HAS under those conditions. The developing agent will remain protected against aerial oxygen uptake. The reasons why Kodak advises against replenishment in such cases is most likely because the total volume in a typical home/small tank setup is so small that it's virtually impossible to get a stable developer activity under conditions of replenishment, given the different types of film run through it (the gelatin emulsion itself interacts with the developer, especially influencing its pH), the overall silver density developed in the film, the byproducts that leach out of the film (especially halides) during development, not to mention storage of working solutions between development sessions. The latter is not a concern in a (more or less) continuously used setup as you'd find in a volume lab, where the total working volumes are also larger (easily a few liters for a small machine) and where a heterogeneous mix of films tends to even out the other effects I mentioned.
A larger volume is simply more stable and therefore easier to keep in check with a replenishment system. A tiny (and intermittently used) system such as a home processing situation is easily thrown off-balance and will easily drift far out of spec if you try to reuse and replenish it. It's not so much due to oxidation during development, but the entire set of parameters of the system.
C-41 is designed for a standard development time of 3' 15''. The type as well as rate of agitation does make a difference, therefore results are controlled by properly adjusting agitation rates for each during development time.
Ah so I am right that when any article mentions C41 inversíon agitation it should say that the time of 3 mins 15 secs needs extending? Do articles or Kodak say this and what is it they should say in terms of an extension of time?
It's just that I can recall seeing any such recommendation anywhere including here on Photrio
Thanks in anticipation of an answer
pentaxuser
The question here is if moving images from one medium (such as a negative) to another (such as a digital file viewable on a monitor) can be done without the image information being altered.
In my opinion, optical printing exists a similar media move issue. There is always differences between before and after the move transaction of the image data.
It's unclear what you mean by 'static' and 'dynamic' in this context. The chemical processes that occur in an agitated developer are very dynamic indeed; there's nothing static about them. This is true for all processes within the developer given the innate mobility of molecules at higher than absolute zero temperatures. HAS is not the chemical equivalent of a piece of saran wrap being pulled over a pudding or something. Its protection is as 'dynamic' as can be. You seem to doubt that the amount of HAS present in a commercial C41 developer is sufficient to protect a small volume in a rotary tank from getting into trouble in one (or even a couple) of development runs. This is not the case.Oxidation prevention by HAS is static. Agitation is dynamic.
I was saying I am seeking a quick and easy way for... I did not look for answers involving high end lab machines and instruments. I anticipate to take away a quick and easy way and that's a more interesting subject to discuss for me. I have several color analyzers, densitometers (B&W and color), PH meters that are accumulating dusts. I almost plunged into buying a lab in the early 90's. Glad that I moved away from that direction.That's an easy one to answer. Obviously, it can't!
So apart from the other things you said, which I understand, but only partly agree with, the question is: what do you take away from this?
You started with the question how to judge your C41 development process. For many reasons, relying on the output of a scanner isn't a very good way to do this unless it's part of a carefully calibrated imaging chain, which is likely beyond the means or necessity of a home user. An approach relying on optical printing is similarly challenging.
The question remains how relevant it is to know the quality of your C41 development process beyond the obvious informal assessment of just producing images and seeing if they meet your needs. I understand your imaging chain is purely a hybrid one, where you use film for capture and then scanning to proceed into digital post production. This means that there are roughly speaking four areas where the quality of the output is determined (or, if you're cynical: can be messed up):
1: Choice of materials; film & chemistry, but also equipment like scanner and development tanks etc.
2: Film processing
3: Scanning
4: Digital post processing
I anticipate the life of photographic film and associated chemicals to eventually phase out. But before that happens I don't want to pass the remaining opportunity to enjoy the fun it offers. I left photography once for many years. The productivity of darkroom work simply wore me out. The introduction to the market of film scanners brought me back into it. The high tech way of transitioning images from film to digital file is something that deserve film shooters to dig deep into it and benefit from it fully.To an extent, all of these items are black boxes. But some have more potential for both mess-ups and quality gains than others. Let's see:
#1 is a simple one: we have very little influence on the materials, so the best shot we have is to buy materials from a reputable manufacturer and use them before they go bad.
#2 is for the home user likewise a black box for all intents and purposes, because even if you determine that the process is out of spec, it's often difficult to figure out why. On the other hand, a process that's run on decent materials (see #1) and according to the manufacturer's instructions combined with common sense tends to perform more than adequately for virtually every purpose.
#3 you can either work in a color-managed workflow using calibration targets, but the problem is that this only goes so far and relies on targets on the exact type of film you're using (and a scanner that actually supports such a workflow). The alternative is to experiment with various scanning settings to find something that seems as consistent as possible, and then hope for the best. Outsourcing scanning is a third option, but this makes the black box only blacker still.
#4 this is a part where the artist/photographer has a massive degree of control and opportunities to steer the result into virtually any imagined direction. The limitations are posed virtually only by the user's abilities/competence, given that he starts with something that's halfway decent (i.e. evenly developed film with at least somewhat useful color data).
Given the fact that your odds of actually making a difference in terms of the end result are very limited in #1 through #3, with basically your best shot being "just do as it says on the tin", it seems very obvious to me what the question should really be about.
So my honest answer to the initial question you asked, is: go read some books on color grading. As long as you can produce negatives that don't have horribly apparent defects, this is the one area in your workflow where an investment in time and perhaps some software is really going to pay off dramatically.
You perhaps now also understand why the vast number of photographers have transitioned to digital. It reduces 3 pcs. of black boxes to just one, leaving their hands free to focus on the fourth, which actually really makes a difference. This is not me being cynical about the possibilities of analog photography etc. It's just a sober observation of how people who are serious about the craft and approach matters rationally produce images.
One can agitate the film aggressively or moderately thus the oxidation of the developer varies dynamically. HAS provides a long term protection to the developer when it is in the state of storage in the bottle. That is static. I apologize if I don't use the word appropriately.An irrational approach I find very interesting and in fact I would encourage if you're inclined to it. But if you choose that route, don't tire yourself with boring questions about how to get your C41 process running on spec.
It's unclear what you mean by 'static' and 'dynamic' in this context. The chemical processes that occur in an agitated developer are very dynamic indeed; there's nothing static about them. This is true for all processes within the developer given the innate mobility of molecules at higher than absolute zero temperatures. HAS is not the chemical equivalent of a piece of saran wrap being pulled over a pudding or something. Its protection is as 'dynamic' as can be. You seem to doubt that the amount of HAS present in a commercial C41 developer is sufficient to protect a small volume in a rotary tank from getting into trouble in one (or even a couple) of development runs. This is not the case.
Also, in my experience, C41 developer that's used (with constant agitation) preserves just fine and will work virtually the same weeks after its first use. It's something I don't recommend because repeated use will eventually result in drift, but the developer doesn't magically oxidize all of a sudden after it's been used once. This is evidenced by the lack of color change - don't be confused with sensitization and antihalation dyes from the film leaching into the developer.
Really, you're making far too much of this supposed oxidization problem. If you use your developer one shot, or even twice, it's not an issue. Not even if you go crazy shaking it during processing (it evades me why you would, however). Storage conditions are far more relevant.
TL;DR: it's very easy to get lost in details that turn out to be irrelevant, and to complicate matters that are unproductive. In my view, you're heading down this path very fast. That's OK, but if you want to make images, this is not really the way to go.
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