Wanting to try reversal processing but also not die

Raghu Kuvempunagar · Apr 12, 2020

138S said:
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 powerful first developer, how much density is the "unused" halide going to form after second development? If your highlights are off the target (which is 0.3D + base + fog) by, say, more than 0.2D, then the first developer needs a relook. So the hit that DMax takes, for a good first developer, is probably 0.2D or smaller. Is it really a big concern assuming you already are getting good enough density?

138S · Apr 12, 2020

Eldorado Quibbo said:
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.
Grant & Haist states that the silver halide solvent has also the function of physically develop the Ag specks so to redeposit some Ag in the growing area. This allow a greater DMax achievable.

I know well the Foma kit, at 15k views, my most "flickr-succesful" shot was just Silvermax with the Foma kit, it was a happy accident because I did nothing, job was done by the girl, the F5 and the Foma kit. I was not even aware about that I had a relatively good shot until I saw it developed:

But there are many ways to process BW slides, and for sure we can do a lot with many other recipes. Me, now I'm interested in learning how to obtain an extended dynamic range for the projection.

Raghu Kuvempunagar · Apr 12, 2020

138S said:
Perhaps that was about kodak films, for sure Velvia reaches 4.0D, delivering impressive projections.

Here's some data about color reversal films:

source: https://cool.culturalheritage.org/byauth/vitale/digital-projection/

Now compare the above data with what @iandvaag reported from his experiments:

iandvaag said:
Using D-67 I've had success with:
- Ilford Delta 100 (15 min at 20 °C; gamma = 2.7; DMax = 3.5; DMin = 0.3)

D-67 uses thiocyanate BTW.

Lachlan Young · Apr 12, 2020

138S said:
Modern films also have lots of "unused silver"

They don't have anything like as much as you'd assume - they're pretty efficient compared with older emulsions. Films intended for reversal processing have to be designed to be coated at a higher silver/ m2 quantity to help ensure a good Dmax. This is a well known fact of film system design. Document films can deliver good results in reversal because as a consequence of their high contrast design aim, they contain more silver. You can get a good black out of quite a lot of non-reversal films in reversal processing, but the absolute numbers may not be as good as specifically designed emulsions. It's also more a question of useable dynamic range vs max black (which will be higher in contrastier films).

You're spending a lot of time guessing about relatively irrelevant parts of the process and not taking enough time to carefully understand the critical properties and dynamics of the first and second developers to ensuring the film has a good black and a clean highlight. Or understanding that there are fundamental limitations to the process caused by the very nature of reversal processing. At the end of the day, if you want serious Dmax, contact print your negs to another neg film. End of story.

138S · Apr 12, 2020

Lachlan Young said:
At the end of the day, if you want serious Dmax, contact print your negs to another neg film. End of story.

Yes... this is a sound solution, no doubt. BW Release film is ideal for that.

Lachlan Young said:
They don't have anything like as much as you'd assume - they're pretty efficient compared with older emulsions.

No assumption, what I measured, easily you have 1.0D of unused silver, this were tests I made with HP5+

DR5 reaches 3.45D with HP5+ (http://www.dr5.com/blackandwhiteslide/hp5dev-1.html)

In those curves I reached 3.1D with a 0.7D fog, or 2.5D with 0.4D fog

Later with more energy and silver solvent I ended reaching 0.2D DMin and 2.8DMax , for a total 2.6D range, while DR5 probably reaches a 3.3D range, a 0.7D improvement over my yield. In part toning has an influence, but probably DR5 manages the unused silver better than me.

...with TMX DR5 reaches 3.8D (http://www.dr5.com/blackandwhiteslide/tmxdev1.html) but with D100 DR5 reaches 4.4D (http://www.dr5.com/blackandwhiteslide/delta100dev-1.html)

I guess this is because kodak makes a more efficient usage of silver than ilford, having D100 a higher DMax potential from unused silver, and because efficient DR5 usage of the unsued silver.

4.4D is a powerful value that made me think, probably D100 is a film I'll check well for reversal.

Raghu Kuvempunagar said:
Here's some data about color reversal films:

Velvia DMax depends a bit on the color developer freshness, if it is fresh it reaches well 3.9 to 4.0, It's not that important if Velvia reaches 3.8D or 4.0D, but anyway 3.8D is much higher than most home BW reversed slides.

My view: DR5 shows me that if I learn what necessary I will be able to make BW slides that are as powerful as Velvia, regarding projected DR. I see Velvia slides more powerful (for some scenes) than those BW slides I reverse at the moment.

Eldorado Quibbo · Apr 12, 2020

138S said:
I guess this is because kodak makes a more efficient usage of silver than ilford, having D100 a higher DMax potential from unused silver, and because efficient DR5 usage of the unsued silver.

No, there's no such a thing than "unused silver". It would be a waste of money for Ilford (or any other manufacture) to design a film with a large quantity of silver that is "unusued" and washed away by the fixer.

Eldorado Quibbo · Apr 12, 2020

Raghu Kuvempunagar said:
Here's some data about color reversal films:
View attachment 243757
source: https://cool.culturalheritage.org/byauth/vitale/digital-projection/

Now compare the above data with what @iandvaag reported from his experiments:

D-67 uses thiocyanate BTW.

Notice the hugely varying contrast values at which the DMax is taken...
It's like comparing orange to apples.

138S · Apr 12, 2020

Eldorado Quibbo said:
No, there's no such a thing than "unused silver". It would be a waste of money for Ilford (or any other manufacture) to design a film with a large quantity of silver that is "unusued" and washed away in the fixer.

There is !!! See this: http://www.dr5.com/blackandwhiteslide/delta100dev-1.html

DR5 with Delta 100 reaches 4.4D. That high density comes from "unused silver" you usually remove with silver solvent.

Anyway, make a test: totally overdevelop a film end with lights open, measure density. Then measure your DMax. You will have a clue of how much unused silver you have.

Eldorado Quibbo · Apr 12, 2020

138S said:
Anyway, make a test: totally overdevelop a film end with lights open, measure density. Then measure your DMax. You will have a clue of how much unused silver you have.

No, even with a full exposure to light you can't develop all Ag grains, there will be a quote of them that will be "undevelopable" by any means but that has nothing to to with "unused silver" concept you describe.

From Grant & Haist, Modern Photographic Processing, vol.2 page 317:
Such an excessive exposure still might not give clear highlights in the
positive image, however, because, as Lloyd E. Varden has pointed out,
"there will remain some exposed grains that will not develop because they
have become solarized." Such nondevelopable grains of silver halide crystals
will then form a considerable fog level in the positive image. Joseph S.
Friedman also concluded that "it was impossible to ever expose and de-
velop an emulsion in such a manner that 100 % of the silver halide grains
become developed.

And from page 319:
The action of the silver halide solvent in the first developer effectively
increases the speed of the reversal film or paper, because a shorter light
exposure may be given and the solvent's action will insure that the high-
lights of the positive image will be clear. The fact that all grains in a photo-
graphic emulsion layer cannot be made developable by light exposure is
thus circumvented by giving a less-than-total exposure for all the silver
halide crystals, developing the exposed silver halide fully to form a high-
contrast silver image, and removing some of the remaining silver halide by
solvent action to insure a clear positive highlight. The solvent is particularly
effective where most needed-that is, in the areas of maximum exposure,
as these areas become the highlights of the positive image. Here, only small
silver halide crystals of low light sensitivity, probably of high silver iodide
content, remain after chemical development of the negative image. It
is much easier to remove these silver halide crystals by solvent action than
by attempting to expose and develop them. The presence of the developed
silver acts as a catalyst for the solvent action of the thiocyanate. Most silver
is formed in the areas of maximum light exposure. Thus, the presence of the
most silver filaments results in the maximum solvent action, which is needed
to remove the less sensitive silver halide from the region that will be the
highlights of the positive image.

Anon Ymous · Apr 12, 2020

Meanwhile, the OP has regretted asking about reversal processing and probably thinks this is some kind of black art.

Eldorado Quibbo · Apr 12, 2020

Anon Ymous said:
Meanwhile, the OP has regretted asking about reversal processing and probably thinks this is some kind of black art.

He's not probably interested because he hasn't replied, not once.
We don't know for example what film he/she is using...

Lachlan Young · Apr 12, 2020

138S said:
In those curves I reached 3.1D with a 0.7D fog, or 2.5D with 0.4D fog

Later with more energy and silver solvent I ended reaching 0.2D DMin and 2.8DMax , for a total 2.6D range, while DR5 probably reaches a 3.3D range, a 0.7D improvement over my yield. In part toning has an influence, but probably DR5 manages the unused silver better than me.

Developer composition; development time; EI & format used; reversal method; second developer? Without those, your measurements are meaningless.

Before trying to make an apple look like an orange, remember that Velvia has a different design aim in contrast terms from HP5+ & that you are not going to be able to force fit HP5 into Velvia's range.

138S · Apr 12, 2020

Lachlan Young said:
Before trying to make an apple look like an orange, remember that Velvia has a different design aim in contrast terms from HP5+ & that you are not going to be able to force fit HP5 into Velvia's range.

With development you adjust the reverse C.I. of the slide. In fact you have a narrow margin for the slide CI, if the slide has to look nice in a projection. A good BW slide has approx the same gradient than Provia, you cannot change that much, if not the slide would look weird (or say very "creative") in a projection.

138S · Apr 12, 2020

Eldorado Quibbo said:
No, even with a full exposure to light you can't develop all Ag grains, there will be a quote of them that will be "undevelopable" by any means but that has nothing to to with "unused silver" concept you describe.

First, don't confuse crystals with grains. You have crystals before development and grains after development. Halides have a crystalline structure, grains are polycrystalline metallic clumps.

Possibly I've not expressed it well: it's not about re-exposing all "unused silver", it's the counter, it's about not re-exposing it but infectiuosly developing it proportionally to local density .

Even in the case the "unsued silver" is not exposed (electronically charged) it can be developed by infectious development, this is the way in what we can take advantage from it to increase DMax. Infectious development of the "unused silver" proportionally builds density in the shadows and not in the clear highlights, this is the concept you are missing. All silver halide in the film is developable, if energy/time of the development is enough.

Look, DR5 reaches 4.4DMax with Delta 100 with still clear highlights, probably with your home technique you may not be able to reach even 2.5D without starting to build excessive fog, now you may have a guess about the "unused silver" role in a wise reversal development. We usually disolve it... but perhaps there is another choice, think in that atonishing 4.4D.

Eldorado Quibbo said:
He's not probably interested because he hasn't replied, not once.
We don't know for example what film he/she is using...

He/she got plenty of information about bleaching, as this was acomplished I guess that OP can be happy. There is no harm in debating related concepts about slides as OP has been well served yet.

Lachlan Young · Apr 12, 2020

138S said:
Look, DR5 reaches 4.4DMax with Delta 100 with still clear highlights, probably with your home technique you may not be able to reach even 2.5D without starting to build excessive fog

Unless you can independently verify DR5's claims, do not repeat it as fact.

You also need to tell us what your developer, development time, EI, format of HP5+ used, reversal method and second developer you used in the results you posted earlier before anyone can draw any conclusions about the claims you make.

Eldorado Quibbo · Apr 12, 2020

138S said:
With development you adjust the reverse C.I. of the slide. In fact you have a narrow margin for the slide CI, if the slide has to look nice in a projection. A good BW slide has approx the same gradient than Provia, you cannot change that much, if not the slide would look weird (or say very "creative") in a projection.

Again a big NO.
In b&w reversal contrast is inherent to that particular film and you can't do much to change it.
It's "built in".

Eldorado Quibbo · Apr 12, 2020

138S said:
First, don't confuse crystals with grains. You have crystals before development and grains after development. Halides have a crystalline structure, grains are polycrystalline metallic clumps.

Possibly I've not expressed it well: it's not about re-exposing all "unused silver", it's the counter, it's about not re-exposing it but infectiuosly developing it proportionally to local density .

Even in the case the "unsued silver" is not exposed (electronically charged) it can be developed by infectious development, this is the way in what we can take advantage from it to increase DMax. Infectious development of the "unused silver" proportionally builds density in the shadows and not in the clear highlights, this is the concept you are missing. All silver halide in the film is developable, if energy/time of the development is enough.

Look, DR5 reaches 4.4DMax with Delta 100 with still clear highlights, probably with your home technique you may not be able to reach even 2.5D without starting to build excessive fog, now you may have a guess about the "unused silver" role in a wise reversal development. We usually disolve it... but perhaps there is another choice, think in that atonishing 4.4D.

He/she got plenty of information about bleaching, as this was acomplished I guess that OP can be happy. There is no harm in debating related concepts about slides as OP has been well served yet.

I really don't care how much DMax I get as long as the slides, upon projection, look fantastic. And they do, in the Foma reversal kit. I've got no interest whatsoever in wasting my tme trying unscientifically all possible film/development combinations only to gain 0.2DMax more.
I'm not the analog equivalent of a pixel peeper.
I can't verify Dr5 claims so I take them with a grain of salt, cum grano salis.
I tend to trust more what Grant & Haist say about not all Ag being developed. I've reported the extract, above. I think it's correct what they say about it.

Raghu Kuvempunagar · Apr 12, 2020

138S said:
My view: DR5 shows me that if I learn what necessary I will be able to make BW slides that are as powerful as Velvia, regarding projected DR.

Velvia has so little dynamic range whereas DR5 claims ten stops of dynamic range for some films.

You might want to shoot two rolls of HP5+ under identical conditions. Pick scenes with different SBR. Get one roll developed by DR5 and develop the other with your 'best' process - the one that's closest to giving velvia like viewing experience but not quite there yet. Compare the results from the two processes using sensiometrically as well as subjectively. It'll cost some money and take time but will be a useful exercise.

138S · Apr 13, 2020

Eldorado Quibbo said:
Again a big NO.
In b&w reversal contrast is inherent to that particular film and you can't do much to change it.
It's "built in".

Eldorado, I guess you should review some basic concepts about development:

In the same way you change contrast of negative film you change slide contrast in the first development, this is a very basic concept.

Eldorado Quibbo said:
I really don't care how much DMax I get as long as the slides, upon projection, look fantastic. And they do, in the Foma reversal kit. I've got no interest whatsoever in wasting my tme trying unscientifically all possible film/development combinations only to gain 0.2DMax more.
I'm not the analog equivalent of a pixel peeper.
I can't verify Dr5 claims so I take them with a grain of salt, cum grano salis.
I tend to trust more what Grant & Haist say about not all Ag being developed. I've reported the extract, above. I think it's correct what they say about it.

Most important thing is if you are happy with what you get. But it's not about 0.2D, it's about additional 2.0D.

Of course DR5 literature has some commercial salt, but those DMax densities stated are true, I've never used DR5 because I usually develop all my stuff and because it's in another continent, but a friend of me has used that service and I've seen those slides, and I've measured densities.

My view is that DR5 slides are well superior to the ones I make, and while personally I don't plan to use any Lab service I want to learn how to improve my personal processing to approach DR5 performance.

Of course, I'm not to tell you what dynamic range your slides should have, it's your personal choice. Me, I want a wider DR than the one I'm obtaining, so I try to learn the way. YMMV.

138S · Apr 13, 2020

Raghu Kuvempunagar said:
Velvia has so little dynamic range whereas DR5 claims ten stops of dynamic range for some films.

Raghu, I was not speaking about scene dynamic range but projection dynamic range. In the table you posted (https://www.photrio.com/forum/threa...g-but-also-not-die.174178/page-7#post-2269100) Velvia 50 has the largest Dynamic Range 6300:1

The dynamic range captured in the scene (latitude) is another thing, but you may easily modify Velvia 50 latitude to match Provia or (discontinued Astia) by simply pulling half and stop (may be a little more), overexposing a bit and shortening development as instructed.

10 stops are 1000:1 in the scene, Velvia has 6300:1 in the projection at 3.8D. With Delta 100 DR5 delivers 4.4D, so probably it may depict 1000:1 SBR with no loss in the screen. It is for this that a well made slide (large DR) is great to portray powerful scenes.

Raghu Kuvempunagar said:
You might want to shoot two rolls of HP5+ under identical conditions. Pick scenes with different SBR. Get one roll developed by DR5 and develop the other with your 'best' process - the one that's closest to giving velvia like viewing experience but not quite there yet. Compare the results from the two processes using sensiometrically as well as subjectively. It'll cost some money and take time but will be a useful exercise.

I still have the DR5 slides of a friend to have a target reference, but this is not necessary as also I've Velvia slides that are just equivalent DR and contrast.

My approach is sensitometric, in fact, but as I've necessary calibration gear calibrations don't cost money: they save money. With a single 4x5" sheet I can make 10 calibrations with different processing settings, this is much cheaper and faster than wasting film and images while correcting processing intuitively.

I've developed an automatic calibration software (that I'm to release as freeware when ready, if anyone wants it, https://www.largeformatphotography.....php?150045-New-darkroom-calibration-software) that allows me a very fast calibration workflow.

Of course, not all is calibration, IMO when processing is mostly controlled then some refinements require real image samples.

Eldorado Quibbo · Apr 13, 2020

138S said:
Eldorado, I guess you should review some basic concepts about development:
View attachment 243840
In the same way you change contrast of negative film you change slide contrast in the first development, this is a very basic concept.

It's crystal clear now that you don't have a clue about reversal. Please stop spreading fake news.
From Kodak own instructions (Kodak Reversal Kit) https://www.21gradi.it/repository/reversal.pdf

You cannot adjust the contrast of slides produced with reversal processing by changing the development time or temperature (as you can in normal processing of black-and-white negative films). Adjusting the development time or temperature will affect only the minimum and maximum densities and effective film speed.

and

Note: Modifying the first developer does not significantly change the contrast of Technical Pan Film.

so you have to change developer!
"In the same way you change contrast of negative film you change slide contrast in the first development, this is a very basic concept." again a big NO!

138S · Apr 13, 2020

Eldorado Quibbo said:
It's crystal clear now that you don't have a clue about reversal. Please stop spreading fake news.
From Kodak own instructions (Kodak Reversal Kit) https://www.21gradi.it/repository/reversal.pdf

You cannot adjust the contrast of slides produced with reversal processing by changing the development time or temperature (as you can in normal processing of black-and-white negative films). Adjusting the development time or temperature will affect only the minimum and maximum densities and effective film speed.

and

Note: Modifying the first developer does not significantly change the contrast of Technical Pan Film.

so you have to change developer!
"In the same way you change contrast of negative film you change slide contrast in the first development, this is a very basic concept." again a big NO!

Sorry, I've not explained it clearly. What you say is true with classic home reversal, this is a calibration I made with a hacked Rodinal and Sn fogging 2nd developer :

We see there the same gradient not matering development time, we have some DMax improvement with extended 1st developer time. The top 6 min curve was using a different solvent...

It is a calibration I made personally, so I'm well aware of that.

What I was trying to propose is a reversal variant with minimal silver solvent effect, with enhanced energy, with partial light re-exposure, and with promoted infectious development of the unused silver, to reach (say) 4.0DMax with Delta 100, while having clear highlights. In that case, with little silver solvent effect, 1st development gradient controls the slide contrast.

My suposition is that a silver solvent rich first developer limits actual development, as unexposed little silver crystals around big exposed crystals are disolved by when infectious development would attack them, so no density-contrast increase would take place after that point.

A more energic developer would develop more before touching unexposed crystals are destroyed by the solvent... so what you say is true for regular BW reversal.

...but consider that I was talking about another situation: no silver solvent, when this limitation if not acting then 1st development time rules on contrast, which follows Mr. Woods recommendation, and he is the one offering 4.4D from Delta 100

Raghu Kuvempunagar · Apr 13, 2020

@138S:

Consider this, for the sake of discussion:

Let's assume that base + fog is as low as 0.3D.

Now, highlights needs to be placed at base + fog + 0.3D, ie at 0.6D as per scientific consensus. Otherwise the highlights will appear dull.

Gamma in the straight line portion needs to be 1.8 for best projection viewing experience.This means each stop of exposure gets ~0.54D.

So mth stop of exposure after the most important highlights gets density 0.6 + 0.54m. If we take m = 5 the density becomes 3.3D. So with 6 stops of SBR, we hit a density of 3.3D. As per scientific consensus on the subject, the contribution of densities higher than this to the viewing experience is questionable.

Now, if @dr5chrome is guaranteeing 10 stops of dynamic range, then either he's not giving you a gamma of 1.8 throughout (which means less than optimal contrast for projection) or there's significant compression of highlights and shadows.

removed account4 · Apr 13, 2020

EASmithV:

if you have some shallots in your cupboard and a little bit of time on your hands
https://www.photrio.com/forum/threads/edible-film-developers.33501/page-12#post-478559
the OP from the thread I linked to has returned ! and is stoked to refine exactly what you are trying to do
J

138S · Apr 13, 2020

Raghu Kuvempunagar said:
@138S:

Consider this, for the sake of discussion:

Let's assume that base + fog is as low as 0.3D.

Now, highlights needs to be placed at base + fog + 0.3D, ie at 0.6D as per scientific consensus. Otherwise the highlights will appear dull.

Gamma in the straight line portion needs to be 1.8 for best projection viewing experience.This means each stop of exposure gets ~0.54D.

So mth stop of exposure after the most important highlights gets density 0.6 + 0.54m. If we take m = 5 the density becomes 3.3D. So with 6 stops of SBR, we hit a density of 3.3D. As per scientific consensus on the subject, the contribution of densities higher than this to the viewing experience is questionable.

Now, if @dr5chrome is guaranteeing 10 stops of dynamic range, then either he's not giving you a gamma of 1.8 throughout (which means less than optimal contrast for projection) or there's significant compression of highlights and shadows.

Well, for the moment those 10 stops would be useful for the scanning, and nice in a powerful light table with a magnifier. IMO the way that DR is good for the projection depends on our setup, the screen grain is very important, if it has a narrow viewing angle then it will conserve way better the slide DR with way less parasite light. also the room size and dark walls are important. With dark walls and a very directional screen reflection you will enjoy that range. An small white room with a dull screen won't show the full potential, I guess.

Wanting to try reversal processing but also not die

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