Sorry I really don't remember where I found the video.That's interesting - where was this video posted? I've found some videos of the machine on DR5's Facebook, but it'd be useful to get a handle on what he's doing. Running a couple of rounds of intensification would not surprise me given that it could use dichromate like the bleach bath and reduce the need for having Agfa etc's level of knowledge in the dynamics and behaviour of the first developer. It is striking that the Copex films he claims won't run in his system will run just fine in the official Scala process. Almost as if Agfa knew what they were doing and invented a process that worked with different grain structure approaches...
Back around 1973 I went to a lecture by a Research student at Birmingham School of Photography, he was Reversal processing Ilford films mostly FP4 and Pan F and then making Reversal prints on Ilfobrom, the image quality was superb.
Is anything known about his process including the first developer by any chance? It's a pity if it's all lost for good.
If I remember correctly in Grant & Haist excellent books, on the reversal section, there's written that the human eye cannot discern densities above 2.2 or 2.4.
But eye moves rapidly to acquire a target (saccades), it re-adjusts its exposure by adjusting "exposure" allowing by a much more wide dynamic range in practice, ultimately (after adaptation) 46 stops.
In fact Velvia slides reach near 4.0D, these are nice slides, depicting well real scenes. Often 2.2DMax slides are boring.
Sure outdoors you feel the difference between a cloudy day and an sunny day. At 2.2DMax you may show a cloudy day in the projection, at 4.0DMax an slide steals the show. No hype: a powerful show.
It says though color reversal films can have a maximum density of 3.0-3.5 (dynamic range >1000).
in practice the available dynamic range is reduced to 300:1 due to screen flare, ambient light and other factors.
by varying the time or intensity of the re-exposure you can fine tune the final results. alternately the timing of the 2nd developer could be varied so development wasn't to completion. I should add these were techniques used for machine processing of B&W cine reversal films.
I dunno.But eye moves rapidly to acquire a target (saccades), it re-adjusts its exposure by adjusting "exposure" allowing by a much more wide dynamic range in practice, ultimately (after adaptation) 46 stops.
In fact Velvia slides reach near 4.0D, these are nice slides, depicting well real scenes. Often 2.2DMax slides are boring.
Sure outdoors you feel the difference between a cloudy day and an sunny day. At 2.2DMax you may show a cloudy day in the projection, at 4.0DMax an slide steals the show. No hype: a powerful show.
Sorry I really don't remember where I found the video.
I clearly remember the display. There were two bleach baths, two reversal baths and some round of intensification at the end, which presumely being selenium or gold, or both.
Dr5 states is not able to run also all regular Fomas films. That's not the case because in the Foma kit Fomapan 100 (not the R version) reverses just well.
Yes, that's the video.Found it on the DR5 Instagram page - my transcription of the thing is: Developer/ Wash 1/ Wash 1/ Bleach 1/ Bleach 2/ Wash 2/ Clearing Bath/ Wash 3/ Reversal Neutral/ Reversal Sepia/ Stop/ Fix/ Wash 4/ 'FT'/ Wash 5/ PF [Photoflo?]/ DR [Drier?]/ Drying stage. Several things I note: the two bleaches may be to maximise bleach lifespan; the Sepia reversal bath is running at about 60oC as opposed to the neutral reversal at 27oC - makes me wonder if it's using Hypo Alum, which could have useful properties because of its bleaching effect; and the mystery 'FT' bath - could it be 'Fixer Thiocyanate' or 'Ferricyanide Thiosulfate', or one of many other options relating to clearing highlights?
Yes, that's the video.
FT could stand for F(something like first) T= toner ?
I tried to substitute light re-exposure using a borane redeveloper or a thiocarbamide one in the Foma kit. Both chemical redevelopers yielded very dense slides that needed farmer's reducer.'Flemish Toner' would be the obvious one - which is Selenium Sulfide I think
Are redevelopers basic?
I'm assuming the sepia redeveloper to be thiocarbamide based and the neutral redeveloper to be a borane dimethylamine complex...
Anyone can chime in?
I tried to substitute light re-exposure using a borane redeveloper or a thiocarbamide one in the Foma kit. Both chemical redevelopers yielded very dense slides that needed farmer's reducer.
However I don't get the use of a stop bath after the chemical redevelopment: there's no need of it.
If my memory still serves me well, Kodak uses a double permanganate bleach.
Agfa suggests using of 20g/liter of sodium hexametaphosphate to lenghten the permanganate bleach useful lifespan.
I've used a Bellini prototype redeveloper based on dimethylamine borane complex.The Scala process redeveloper (it's disclosed in a patent I linked to upthread) has a pH of 11.0 & is used after a light re-exposure. The first developer has a pH of 10.2
I've linked to the patent for the Agfa bleach modification alongside the patent that appears to disclose the Scala process.
Interesting that you got dense transparencies - Foma disclose a reversal bath using SnCl2 and p-Aminophenol HCL - to be followed by a wash & then redevelopment as normal...
I've been messing around reversal development off and on for awhile now. I'm still experimenting, but I think this is my target:
Rodinal 1:10 with 2g Sodium Thiocyanate per liter for 15 minutes @ 20C with rotary agitation
I tried 1:10 at 20 minutes, and 1:5 at 15 minutes. Both were overkill, and they ended up looking faded where the blacks weren't as dark. They looked the same except the highlights were more blown out at 1:5.
I gave up on the light exposure part and went with a fogging developer since I think it was causing inconsistent results. I had to expose it to light underwater or else I would get water drops imprinted on the film.
What we do with unused silver ? Eliminating it with silver solvent ? Building fog if we do not eliminate it ?
Let me tell you my view on how we can use that unused silver to increase DMax without generating fog (without damaging DMin).
That unsued silver has very, very low ISO, but we fog it if we use a fogging developer or if our re-exposure is total... if our reexposure is total then that silver has to be eliminated by a solvent at some point to clear highlights...
But see next strategy:
> We don't develop or disolve the unused silver, but with a very energic first development we (infectiously) develop that unused silver in the highlights, and we clear it in those highlights with the bleaching.
> We make a controlled re-exposure that is not enough to expose the "unused silver": mostly it wont develop, it won't generate fog, we will remove it in a final fixing.
> If we use a very energing second development that "unused silver" will infectiously develop in the shadows, increasing DMax.
In that way we use the "unused silver" to get an extended DMax with no fog, so a boosted Dynamic range.
David Wood further adds a toning, wich is a kind or proportional stain that increases both contrast, and dynamic range.
Well, Fuji makes Velvia 50 with 4.0DMax power. It shines in the projection. In my experience those BW slides sporting a high dynamic range are quite powerful when projected !!
I've used a Bellini prototype redeveloper based on dimethylamine borane complex.
And I've used the B part of the Foma sepia toner kit, basically a thiocarbamide solution.
In both instances I've got *very* dense slides that I've got to "lighten" with a ferricyanide reducer.
With redeveloper I mean a solution that bypass the light re-exposure, not the second developer.
That is thiourea, sulfides, dimethylamine borane, and other quite more toxic and dangerous compounds like idrazine and so on...
my transcription of the thing is: Developer/ Wash 1/ Wash 1/ Bleach 1/ Bleach 2/ Wash 2/ Clearing Bath/ Wash 3/ Reversal Neutral/ Reversal Sepia/ Stop/ Fix/ Wash 4/ 'FT'/ Wash 5/ PF [Photoflo?]/ DR [Drier?]/ Drying stage.
In fact Velvia slides reach near 4.0D, these are nice slides, depicting well real scenes. Often 2.2DMax slides are boring.
In film, due to technical reasons, reversal films are rather much limited to a dmax of 3.0 or thereabouts,
...
In any event, all of the above is true for color and B&W films.
PE
Quoting PE from Post #25 https://www.photrio.com/forum/threads/latitude-of-colour-negative-film.55294/
The films Ian was talking about these controls being used on were pre-WWII technology - heavily polydisperse, active gelatins, curve shapes not ideal, a lot of unsensitised silver. What you might have been able to get away with in the 1930's is probably going to not work terribly well with modern grain structures, additives & highly controlled growth and sensitising measures.
Note too that many of the films recommended for DR5 often seem to have EI's suggested that amount to a fair bit of overexposure & that getting to box speed requires 'pushing'. That suggests that the process has issues chemically accessing the silver in an optimal way to maximise speed for many emulsions.
Modern films also have lots of "unused silver". If you home develop BW slides you will that your slides fail to reach film DMax by a great extent.
That has nothing to do with "unused silver" (whatever that means).
With a properly calibrated system a true DMax is achiveable even at home.
I don't really know what Foma put in their first (=second) developer in the kit but the results are stunning. A truly calibrated system with a fantastic emulsion. This is my piece of advice to the original poster: get the Foma reversal kit and the Fomapan 100R. You'll save yourself tons of money of burned films and spare time.My view is that is has to do with it. Unsued silver halide is the one not developed by 1st developer and that is to generate fog in the second developer if it is not removed by silver solvent in first and/or 2nd development, or by other means like a density reducer.
At home, when you use a silver solvent to clear highlights (and obtain a good DMin) you also decrease your DMax potential, as the silver you disolve won't generate density.
With a wise processing you may infectiously develop that silver to add density in the shadows and not in the highlights. Some low Dyn Range scenes won't require a high DR in the slide ...but some scenes are to benefit from an extended DR in the slide, showing bright hightlights and fully detailed deep shadows at the same time. One thing is a 2.3D Dynamic Range slide, and thing is one sporting 4.0D.
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