Tips for belini e6

[MingMingPhoto]

No, the partial dye is located near the silver, suspended in the gelatin emulsion. They are distinct molecules, unrelated and unlinked.

The partial dyes are called "dye couplers" because they couple with another molecule later on: the oxidized developer. These partial dyes are typically suspended as oily globules in the emulsion. The silver halide is present in crystalline form, also in the emulsion. The idea is that if a developer molecule is oxidized by developing a silver halide particle, it floats away and finds a dye coupler molecule nearby. In pinciple, it could also float pretty far away, even to another color layer and link with a dye coupler there, but several provisions are taken in emulsion making to prevent this from happening. However, this migration does happen to a limited extent and it's part of the reason why we speak of 'dye clouds', since they tend to be somewhat vague/ill-defined blobs. It's a bit like dropping fountain pen ink onto a wet piece of paper.



No bonding between dyes and silver happens.



That's it. It's indeed a bit sloppy in principle, and this is one of the challenges of emulsion making - to control the sloppiness.



Yeah, I think in laymen's terms as you and I are capable of that's a pretty good shot. Something with electrons, holes and redox reactions. For me, that's been good enough up to the present; it's one of those things I'll dive into when/if needed.

what's your background? what things to you photograph and what made you get into film?

 

[koraks]

what's your background?

Unrelated to photography, but an interest in all things technical, which manifests itself in photography mostly, at least over the past 15 years or so.

what things to you photograph and what made you get into film?

Ah...nothing special really. Lately mostly landscape stuff, which varies from classic scenery type shots (yaaawn....) to more abstract isolations (mostly 'yawn' as well). And holiday snapshots when we travel. My talent and interest is more at the technical level.

Since I don't much enjoy the process of making inkjet prints, and I do like to make photographic prints, film is pretty much the only option left. I've done wet plate for a while, but it was much too limiting due to the practicalities involved.

 

[MingMingPhoto]

Unrelated to photography, but an interest in all things technical, which manifests itself in photography mostly, at least over the past 15 years or so.



Ah...nothing special really. Lately mostly landscape stuff, which varies from classic scenery type shots (yaaawn....) to more abstract isolations (mostly 'yawn' as well). And holiday snapshots when we travel. My talent and interest is more at the technical level.

Since I don't much enjoy the process of making inkjet prints, and I do like to make photographic prints, film is pretty much the only option left. I've done wet plate for a while, but it was much too limiting due to the practicalities involved.

good to have you

 

[koraks]

That's kind of you, thanks. You too!

 

[Rudeofus]

what is the difference between silver iodide and bromide? why do they choose bromided mostly for e6?
and ok! hopefully the other person has a momnet to chime in as well!

Since @koraks answered all other questions very well to the best of my knowledge and referred this one to me, allow me to take a shot at answering this one.

The main differences between Silver Bromide and Silver Iodide from a photographic perspective are:

1. Silver Iodide is a lot more insoluble than Silver Bromide. This means in practice, that you need more energy to develop Silver Iodide, and that quite a bit of Silver Iodide will likely remain undeveloped. Remember, that if you develop Silver Iodide, you release iodide ions, which act as powerful restrainers. Look at the characteristic curve of Ilford Delta 3200 to see this effect in action. You do not want such a curve for slide film.
2. Silver Iodide is blue sensitive, whereas Silver Bromide is only sensitive to UV light. Therefore the blue sensitive layer needs no sensitizing dye, which greatly boosts sensitivity. This makes core shell emulsions so attractive: their surface is mostly Silver Iodide, which boosts sensitivity, whereas the inner part is mostly Silver Bromide, which is easier to develop in bulk.

 

[MingMingPhoto]

Since @koraks answered all other questions very well to the best of my knowledge and referred this one to me, allow me to take a shot at answering this one.

The main differences between Silver Bromide and Silver Iodide from a photographic perspective are:

1. Silver Iodide is a lot more insoluble than Silver Bromide. This means in practice, that you need more energy to develop Silver Iodide, and that quite a bit of Silver Iodide will likely remain undeveloped. Remember, that if you develop Silver Iodide, you release iodide ions, which act as powerful restrainers. Look at the characteristic curve of Ilford Delta 3200 to see this effect in action. You do not want such a curve for slide film.
2. Silver Iodide is blue sensitive, whereas Silver Bromide is only sensitive to UV light. Therefore the blue sensitive layer needs no sensitizing dye, which greatly boosts sensitivity. This makes core shell emulsions so attractive: their surface is mostly Silver Iodide, which boosts sensitivity, whereas the inner part is mostly Silver Bromide, which is easier to develop in bulk.

thank you for stepping in!

1. Idk how to read curves, but this is good for starting me to learn about them. just looked at it. so you're saying no mater how much dev you have because iodide releases restrainers it will never be able to fully develop a roll of film mostly made of iodide?

2. blue sensitve? does this mean that it is not red and green sensitive? also bromide being UV sensitive + visible light sensitive? I'm having toruble getting this second part would you mind elaborating?

 

[koraks]

@Rudeofus, many thanks for sharing your knowledge. I knew it was something along these lines, at least the first point, but you're just better at formulating it clearly (i.e. you understand it better than I do).

1. Idk how to read curves, but this is good for starting me to learn about them. just looked at it. so you're saying no mater how much dev you have because iodide releases restrainers it will never be able to fully develop a roll of film mostly made of iodide?

To an extent, yes. Look at the Delta 3200 curve:

Notice how it slopes off; that's the inhibition that's apparently the result of iodide release during development.

2. blue sensitve? does this mean that it is not red and green sensitive? also bromide being UV sensitive + visible light sensitive?

Silver halides are not sensitive to green or red light. In fact (and @Rudeofus, please help me out here if you will), the blue-sensitivity is also quite limited, even for silver iodide. Frustratingly, good data is surprisingly hard to find, so I'm perhaps grasping at straws if I latch on to this one:

(source)
The idea is that absorbance is a good proxy for sensitivity; after all, what doesn't get absorbed, also cannot play much of a roll in terms of rendering a silver halide developable.
Note how silver iodide has sensitivity up to about 430nm. The other species don't 'do much' beyond about 375nm.

@Rudeofus what I wonder is if this is indeed how blue-sensitive layers are being engineered. Looking at e.g. color paper emulsions, which are silver chloride and a little bromide (no iodide) and also their spectral sensitivity plots, they solve the problem differently there. It may (probably will) be different for E6 film, I imagine, but have never looked into sensitization mechanisms. Is it indeed 'bare' silver iodide (with some sulfur sensitization, perhaps a touch of gold etc.)?

 

[Rudeofus]

1. Idk how to read curves, but this is good for starting me to learn about them. just looked at it. so you're saying no mater how much dev you have because iodide releases restrainers it will never be able to fully develop a roll of film mostly made of iodide?

Reading the curves by themselves is rather simple. The horizontal x-axis denotes exposure in some logarithmic scale, and the vertical y-axis denotes density in a linear scale. Density itself (as it is used for photographic film) denotes how much light is absorbed by a somewhat translucent medium. Density itself is a logarithmic measure, so exposure/density plots can be seen as loglog plots. Since we know, how silver halide responds to light exposure and development, we are not at all surprised to see monotonously rising graphs in these charts: higher exposure yields higher density.

The photographic material itself brings with it some relation between exposure and developability of grains, and then the developer has properties of its own. A developer may be more or less restrained by byproducts of development, it may become more active with development. It may run out of steam as it is used up during development. All of this will together set the final result of this H&D curve as it is called.

If you then look at the chemical reaction of development, you will see a competition for silver: while the developer would love to reduce it to metallic silver, the iodide likes its silver ion quite a lot. You will have to argue with the iodide ion to let go of that silver ion. "Argue" means "bring in a powerful development agent". However, that "powerful development" agent may end up developing silver halide grains that were not even exposed, so you may end up with the choice between "partially developed image" or "all grains were fully developed", and neither are good for image making.

I don't know the exact numbers, but fact is, that modern Silver Bromoiodide film emulsions contain no more than a few % iodide.

2. blue sensitve? does this mean that it is not red and green sensitive? also bromide being UV sensitive + visible light sensitive? I'm having toruble getting this second part would you mind elaborating?

@koraks told you already more than I know about direct light sensitivity of silver halides, allow me therefore to skip that part and move right into sensitizing dyes. These are "crazy dyes" (look at their molecular structure in patents to know what I mean), which stick to silver halide quite well, so they will be found on the surface of silver halide grains. These dyes will absorb certain light wavelengths and somehow pass that energy on to the silver halide crystal. Please don't ask me how that works, since I am not a chemist, but these sensitizing dyes do work, and have worked for more than a century.

Looking at @koraks ' graphs, it may be easier to imagine a dye absorbing green or blue wavelength and kicking that silver halide grain into action, and indeed blue and green sensitization existed long before red sensitization became a thing (look for orthochromatic vs. panchromatic film). From what I have been told the sensitizing dyes needed to render silver halide IR sensitive are truly bizarre, and this may be the reason why even IR films were quite insensitive in the IR range of wavelengths.

Sensitizing dyes do imbue spectral sensitivity in the range we want, but at the cost of quite some loss of sensitivity, i.e. you'd need many more red photons to convince red sensitizing dye to kick silver halide into action, than you'd need UV photons to kick silver halide into action by itself. This means: while these 15-20% sensitivity of Silver Iodide to blue light looks lame, it may still be way better than Silver Bromide with blue sensitizing dye.

 

[d_kolobov]

Hi all. Like you, this is my first time encountering a Bellini set.
Questions that bother me, maybe you can help me.
- I use a Jobo CPE rotary machine, which allows me to significantly increase the total amount of developed photographic film. The instructions indicate that the final solution is designed for 12 films, can I increase this quantity using a rotary machine?
- The instructions indicate rinsing after the first developer, but it is not clear in what form, is it just filling with water without agitation? What should I do in my case with the Jobo machine, add water and let it circulate for 2 minutes?
These are the first questions so far, I hope someone can help me))

 

[koraks]

can I increase this quantity using a rotary machine?

Don't count on it, at least for the first developer and probably also color developer. The capacity is based on exhaustion effects, not the volume needed in a tank.

Rinsing is always with agitation.

add water and let it circulate for 2 minutes?

It's better to fill with water, agitate for 30 sec, drain and repeat all this 4 times.

Also, welcome to Photrio, we're happy to have you on board!