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Wanting to try reversal processing but also not die
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Yes... not easy in a non continuous processing, in the complex kodachrome processing it was done 3 times...
Problem is that when totally fogging film the second developer develops the "silver reserve" producing fog, and any path to reduce that fog will decrease DMax.
If we were able to not fog the silver reserve that silver reserve would only develop (in 2nd dev) from infectiouos development in the extreme shadows, delivering deeper blacks...
it is a way I'm exploring... not sure if it will work, I plan a test it throwing controlled lux·second on the bleached film, the idea is increasing DMax without increasing DMin, I plan to do it with contact copies of the Stouffer wedge, so it would be easy to test. If it works it would be easy to do it with sheets, for rolls a "device" would be necessary.
Yeah, David Wood is masterful ! He has been at this game for decades
3 decades !!!
@138S Assuming that you can give a precise reexposure, in order to avoid dense highlights, I can't see any way of avoiding weak Dmax. If you are getting foggy highlights, then there's a chance that you aren't exposing enough in camera. Or perhaps the contrast after first development is weak and you need to extend FD time. Or you used too little potassium thiocyanate, or sodium thiosulfate. And let's not forget that a typical BW film has a relatively dense, tinted base, which isn't ideal for highlights in BW slides.
Only in the pre-1938 version. The Magenta developer became a fogging developer at that point.
Save yourself the effort. Sort out your first developer - that's where the important stuff happens. Everything else essentially has to go to completion otherwise it doesn't work very well. Don't expect to be able to magically produce the results you fantasise about with atypical films. If you spent less time obsessing over CMS 20's spec sheet and more time engaging with & understanding the aesthetics/ limitations of BW reversal materials, you might actually get somewhere.
Please see attached document (http://www.ars-imago.com/productinfos/osbahr_reversal_films.pdf)
Page 12-13...
...shows the unused silver halide. The question is that some Pro Lab jobs (Scala, DR5) do sport a DMax vs DMin that home processing may not reach by far.
This is only a suposition, something I'm to investigate: perhaps a way to obtain an extended dynamic range for the projection is provocating a large infectious (2nd) development of the "Unused Silver" in the shadows but no development of the "Unused Silver" in the highlights.
My reasoning is: if we fog and develop all "unused silver" when we remove that density (solvent, etc) then we also decrease DMax potential... The single way I see to conserve top DMax and min DMin is infecting the "unused silver" in the shadows and not fogging the unused silver...
Disclaimer, just trying to find an explanation for the Pro Lab vs Home yield difference, just speculating while preparing to check it.
@138S You have a comprehensive set of formulae for what is almost certainly the Scala process in US6350563.pdf. Use them (don't bother with the HQ free formulae). Use the bleach in EP1006408B1 if you don't want to handle dichromates. All the chemicals (or reasonable substitutes) are available in home-user quantities. There's no need for further aimless speculation unless those formulae really fail to work at all. If they are good, you should purely need to alter the first developer time to zero in on correct process time. Agfa's photo engineers knew what they were doing, especially given that it was a fully commercialised process. I have a scanned example of CMS 20 run in Scala if that's of any use to you?
I wonder if it wouldn't be easier to do it the old movie industry way -- expose and process for a good negative, then rephotograph or contact print the negative to get a positive (equivalent to making a darkroom print, except too small/too fast to do any significant dodging and burning). There are film stocks made specifically for this, like Kodak 5302 Fine Grain Release Positive.
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exactly. !!!
I agree! making contact copies on release film (or other) is the most powerful way, having the opportunity to make the adjustments we want, we still have the negative to make prints and we only have to make those slides that are worth in the roll.
Still, IMO, nailing the BW reversal processing is a great workflow, it commands a remarkable effort to nail the slide because we have a single opportunity to do it , but it also sports authenticity because there is no possible manipulation. This is an emotional value, perhaps...
Those are quite interesting docs !!!
For CMS 20 nor dichromate nor permanganate bleach are to work. Both metallic silver and halide are totally cleared in a few seconds, delivering a totally clear frame. I tried to dilute a lot dichromate and permanganate, but by when metallic silver is cleared a lot of damage is made in the halides, this is what I could obtain (with diluted bleach) after Ps edition, the frame was very thin and not suitable for projection:
Well, at least it has a vintage look...
Probably those pro lab process CMS 20 slides with another bleach. Copper way is known to work... or perhaps they use some C-41type bleach... what's me, I was not able to properly bleach CMS 20, I'm to try copper...
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While it's fun trying to make reversal work for any film, these sage words of wisdom by PE suggest that a sensible choice of film, first developer and halide solvent goes a long way in getting good results.
Raghu, that PE recommendation is very good. This is the reason why an energic Paper Developer is recommended in most recipes.
Anyway see this "We do not recommend reversal processing HP5 Plus or DELTA 400 PROFESSIONAL film as results are likely to exhibit unacceptably low contrast." This is said by Ilford in his Reversal instructions !!!!
https://www.ilfordphoto.com/reversal-processing/
Then, LOL, see that David Wood can process it with optimal results:
"The most popular film for dr5 simply because of its image quality @ higher iso speeds. Like most of the ILFORD films, HP5 is great for bringing out shadow the detail, especially when you need to scan those dark areas in the image. The "BEST" quality if your needing speed; 320-3200iso exposure latitude. Speed lower than 320iso is not recommend for this film, though it is possible. HP5 produces an old fashion image quality, similar but smoother than TX.
HP5 holds detail in the brightest whites and deepest blacks. For many, It is the favorite film for dr5. DMAX is around 3.45 @400iso "
http://www.dr5.com/blackandwhiteslide/hp5dev-1.html
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My HP5 reversal processing is quite good, still I have to enhace DMin to a lower value. My guess is that I've something to learn.
It could be an issue of fine tuning the first developer and halide solvent which Ilford might not have attempted to do for the two films you mentioned. Some people have complained that Ilford's recommendation of 8-12g of Thiosulphate per liter is too much.
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- mohmad khatab
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copper sulfate (Anhydrous ) is the ideal solution.
Do not use copper sulfate.(pentahaidrate)
Deionized water 300 ml-52 ° C
copper sulfate (Anhydrous ) ......... 50 g
Sodium chloride (without iodine)....50 g
Sulfuric acid (37%) ..........................5 ml
water Up to ................................. 1 L
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This process was only designed to work on a rotary machine (JOBO) that never worked with me manually,
I don’t know, maybe I was wrong about something, I’m currently reviewing myself.
Of course, but it's surprising that a manufacturer of the ilford's size says that about his film, instead showing a suitable recipe, I guess BW slides are not popular enough to deserve their attention...
Well, I was showing that not for that particular recipe, but to bring attention on the "unused silver" factor.
The idea is that if we use silver solvent to clear highlights at the same time we may be also thinning the shadows obtaining a lower DMax...
Just bringing attention to the optimization potential, one thing if making an slide that shows nice in in the projection, and another one is making an optimal job to obtain the Base DMin and 4.0 DMax in the shadows, showing detail in extreme shadows and highlights, while keeping rich mids, in a way the projection faithfully reproduces challenging scenes.
This Silvermax slide, for example:
...it's quite dull in the monitor, I can't edit it to show the contrast between glares and shadows.
Instead in the (boosted) projection contrast is amazing, glares are so powerful that one nearly needs sun glasses to view it, and at the same time shadows in the backlighted duck are fully detailed.
...so what I'm asking is the way to obtain top DMax and base DMin, for a high dynamic range in the projection. Not all scenes require that, of course.
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Delta 400 runs very well in the Scala process run by PhotoStudio 13, as does TMax 400 (you can even have it pushed or pulled a stop). That the Agfa process doesn't seem to suffer the speed losses that DR5 suffers with more modern crystal growth technology films suggests that the Agfa first developer is better at evenly penetrating and thoroughly developing more complex multi layer film constructions without requiring overexposure to ensure all the silver gets used. The first developer in Scala is quite complex once you start to look closely at it. Note that it uses Metol, not Phenidone/ Dimezone etc (quite atypical for Agfa) and has two different kinds of sulfite in it (I suspect that some in-situ HQMS synthesis is going on). It has a developer accelerant rather than a halide solvent to force development of all the silver. No fancy bleaches either, from the available patent documentation, it seems that a dichromate bleach was the initial spec, then there's a patent covering low dichromate bleaches, then finally the German one I cited earlier which uses acidified permanganate and a chelating agent in place of acidified dichromate.
Here is what CMS20 looks like in Scala - a very quick and dirty scan of a not great image, but overall corrected contrast to match the transparency. You can see that on a sunny/ contrasty day the shadows and specular highlights crush & clip very hard respectively - not much roll-off at either end of the straight line. On a shorter contrast scale day, they will likely look a lot more 'normal'. Improvement from here would likely require modification of the first developer. I note that Adotech IV does contain both HQMS and KSCN, so it might make a surprisingly good first developer - but under no circumstances should you use the permanaganate bleach with it.
Well, metol has REDOX 20, IIRC, which is crazy high compared with other agents. It is a powertool to drill into "unused silver" for the highlights, but this solves only a half of the problem.
Let me reiterate the problem I find when working the shadows, after bleaching, if we fog all remaining halide, we still have the "unused silver" fraction that will fog the frame to a certain level, any strategy we use to clear that fog will also damage DMax, isn't it?
Quoting the Agfa patent:
"At the same time, the first development must not be too active and thereby result in an increase in fogging, since this results in decreased maximum densities after reversal development."
In other words you want the lowest possible fog yet still be able to develop all the silver. This is likely why an accelerator was chosen over a more traditional silver solvent.
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Where is that AGFA patent?
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It's attached to post #52
For this reason paper developers are often used as first developer. From Darkroom Coobook:
"While paper developers should always contain some restrainer, when formulating a film developer it is better to decrease the accelerator rather than add more restrainer."
Regular film developers are less suitable than paper developers...
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I've used the Ilford instructions (quoted above) many times in the now distant past with great results. Dela 100 or FP4+ with Ilford PQ as the first developer, instructions followed to the letter. The PDF in the link on their page is dated June 2019 and after a quick scan through it looks like the mixing instructions and steps have not changed since the September 2003 version I have saved down. Also Kodak used to sell a reversal kit for T-Max 100 films - worked well though expensive - no idea if they still sell it though. Biggest challenge is probably getting the raw chemicals these days I suspect.
The slides look great, and to my eyes are still as good today as the day they were processed.
The slides look great, and to my eyes are still as good today as the day they were processed.
Only in the most generic terms could you regard a paper developer as a suitable reversal first developer & even then it's something closer to the 'universal' type of developer that you want. What's more important is how it is engineered to perform in the specific situation.
I wouldn't expect C-41 bleach to work, unless via forming silver chloride and then using an ammonia bath to remove only the chloride.
What I'd be tempted to try with CMS-20 or other document films is apply a halide-reactive toner (like the sepia/sulfide toner that was used in Kodak's T-Max Reversal Kit) to allow developing the positive image before bleaching. Then you can use a C-41 blix to remove the silver developed in the first dev. This probably wouldn't work with conventional films; you'd have too much fog in the highlights where silver that didn't develop took the toner, but CMS-20 shouldn't have much of that problem due to the monodispersed thin emulsion (if I've understood correctly why that makes the film high contrast by nature).
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