Delta 400 - Exposure

[Matt5791]

I dont know about anyone else, but I find that I have to expose Delta 400 at at least 320 and then give it the full guide time for Aculux 2.

Otherwise I was often finding I had really thin negs.

Anyone do the same?

Matt

 

[Roger Hicks]

Dear Matt,

How are you metering? With anything except a spot meter I habitually re-rate films at least 1/3 stop below their ISO speed, except on overcast days/in flat lighting.

Also, I find that I generally need about 5 to 10 per cent more development than the manufacturers suggest, in order to get negs that print well on grade 2.

All this is inside normal variation and is why manufacturers emphasize that you should always make such variations to film speed and development as give you the best negs.

Incidentally, for those who remember the original Delta 400, the current version is between 1/3 and 2/3 stops faster...

Cheers,

Roger (www.rogerandfrances.com)

 

[RalphLambrecht]

I agree with Roger. It's not uncommon to rate film 2/3 slower than box speed. One must consider the box speed to be an absolute minimum. If good shadow detail is required, more exposure helps. B&W negative film has a terrific latitude towards overexposure but is terrible towards underexposure. The reason lies in the way the ISO speed is determined, which doesn't necessarily match what we want from film.

All this depends a bit on developer, but it's a good rule-of-thumb.

 

[craigclu]

I don't know about anyone else, but I find that I have to expose Delta 400 at at least 320 and then give it the full guide time for Aculux 2.

Otherwise I was often finding I had really thin negs.

Anyone do the same?

Matt

That was basically where I ended up when using this combo awhile back. When I was wringing this film out a year or so back, I ended up with Ryuji's DS-10 seeming to be especially compatible with D-400. No funny curve behavior, very stable, very easy to print negatives in every type of light. I had gotten nice results with the Aculux, then ran into supply troubles, then short shelf life issues and simply floated away from it, I guess. It certainly seems well tailored to the modern film emulsions, though. You can quite easily block up highlights when chasing shadow detail with the combo as I recall. 2 gentle inversions/minute seemed to help as too much agitation made this behavior worse for me.

 

[gnashings]

I always find that any t-grains give me thinner looking negs - but when I get in the dark, they seem to pretty much print themselves. Anyone else find this? I thought I was doomed a couple of times - when I first pulled them out of the tank.
Of course, all the advice about over-exposing slightly is spot on, I find. I do it almost instinctively when using the built in meter on most SLR's. 'Tis not the place for it - but when I am forced to shoot colour consumer film (200 especially), I cut the speed right in half. Thankfully we don't have to put up with that kind of crap with our B&W emulsions (although I wish I dialed in a half stop with XP2). OK, drifting off topic.... going, going... gone.
Sorry about that.

Peter.

 

[Roger Hicks]

Dear Peter,

Sorry to be confrontational but Delta is not T-grain. They are very different technologies: tabular (T) versus epitaxial (Delta). As Ilford put it, "Our technology isn't necessarily better, but it is better behaved."

Cheers,

Roger

 

[pentaxuser]

Dear Matt,

How are you metering? With anything except a spot meter I habitually re-rate films at least 1/3 stop below their ISO speed, except on overcast days/in flat lighting.

Also, I find that I generally need about 5 to 10 per cent more development than the manufacturers suggest, in order to get negs that print well on grade 2.

All this is inside normal variation and is why manufacturers emphasize that you should always make such variations to film speed and development as give you the best negs.

Incidentally, for those who remember the original Delta 400, the current version is between 1/3 and 2/3 stops faster...

Cheers,

Roger (www.rogerandfrances.com)

Roger. I'll be taking some B&W at a christening tomorrow Some shots outside but most shots indoors at the reception after the church. Probably flash. i can't check the available light in advance but suspect it's poor. I have the choice of Delta 100 or 400. Both kinds of film were very kindly given by Simon Galley to those of us who were shown round Ilford recently. I mention this because of your comment on its speed.

Which would you advise I use and given your comment about it being 1/3 to 2/3rds of a stop faster than "old Delta" should I rate it at box speed if I choose ID11? However if I go for development in Perceptol I presume that EI 320 or 250 might be advisable if I choose 400 and EI 80 if I choose D100.

Thanks

pentaxuser

 

[Markok765]

For t-grain films i like to rate 1 stop slower

 

[gnashings]

Dear Peter,

Sorry to be confrontational but Delta is not T-grain. They are very different technologies: tabular (T) versus epitaxial (Delta). As Ilford put it, "Our technology isn't necessarily better, but it is better behaved."

Cheers,

Roger

Confrontational? Heck no! Actually, I appreciate the info - thank you for taking the time to tell me! You know, this explains a lot! I was always told that (to simplify and paraphrase) "Kodak has Tmax, Ilford has Delta", basically the same thing. I suppose I have made the mistake of just repeating this bit of "knowledge" blindly - even though I always wondered:
If they are basically the same thing, how come I don't mind Delta one bit, but can never take a photo I like on Tmax?
I guess there is a slight difference, big enough that a) it lets a relative beginner like myself get pretty fail-safe results (relatively speaking) from Delta and b) makes enough difference in the all important "look" that I don't mind one film but can't stand the other (please keep in mind this is a subjective statement, in no way condemning the very capable Kodak products.).
If I could pick your brain some more, could you tell me in fairly simple terms what the difference between the two emulsion types are? Also, why are they generally clumped together (along with Acros)?
Thanks,

Peter.

 

[Matt5791]

Thanks for the replies everyone

Roger - that's very helpful about the rating the films slower unless you have a spot meter. I don't own a spot meter, but with most of the stuff I shoot I wouldn't have time to use it anyway.

I may now have a crack with the Delta emulsions again - I have pretty much stuck with FP4 / TriX recently as have found these traditional emulsions "easier" to expose.

Ralph - I really like your book "Way Beyond Monochrome" - I have found it very useful indeed.

Thanks,
Matt

 

[Roger Hicks]

Dear Pentaxuser,

Probably too late now! I'd be inclined to drop to 320 in ID-11 in contrasty lighting (which churches can be) and 250 or even 200 in Perceptol.

Cheers,

Rogee

 

[Roger Hicks]

Dear Peter,

They are generally lumped together because they are all 'monodisperse emulsions' or 'monosize crystal emulsions', that is, the crystal size is much more tighly controlled than with the old cubic-crystal emulsions. This inevitably means that they can be finer grained for a given speed (fewer big crystals) but it also means that they have less tolerance for over- or under-exposure (big grain in the former case, less shadow detail in the latter) AND a smaller developer repertoire with once again less tolerance of over- and under-development. The control, I believe, is achieved by 'double-jetting' the emulsion ingredients, that is, adding controlled quantities of A and B simultaneously instead of adding A to an excess of B.

T-grains (tabular grains) are, as their name suggests, big, flat crystals. They're also very thin, apparently enough so to reduce blue sensitivity -- photons can go straight through -- which accounts for the extra dye sensitization in T-grain.

Epitaxial is harder to understand, but as I recalll it essentially consists of growing one sort of crystal on the outside of another. Delta crystals are triangular (surprise!) and correctly exposed Delta emulsions are grainier than correctly exposed T-Grain BUT less grainy than over-exposed T-grain where all the development sites run together.

This is a fairly poor summary, because I'm not an emulsion chemist, and besides, I don't have the time to check all my sources in a reply like this, which of course I would do if I were working on a book. There may well be others on the forum who can correct what I have written. But as you say, there clearly is a difference in look and behaviour from the different monodisperse films: a lot more than there would be if they used essentially the same technology.

Cheers,

Roger

 

[RalphLambrecht]

That will do no harm and give good shadow detail.
Most users find 1/3 or 2/3 stop appropriate. Due to meter and development variations from user to user, the actual required exposure might vary, but 2/3 stop is a good start.

 

[Max Power]

Funny thing,
I actually rate it at an EI of 500 and soup it in DD-X for 10:00 at a controlled 20C. FWIW, this is where my Zone tests led me. I use a condenser enlarger, though, so perhaps this plays into it.

I even rate D-100 at 100 for Rodinal at 1+50

Just my $0.02

Kent

 

[Ryuji]

When I was wringing this film out a year or so back, I ended up with Ryuji's DS-10 seeming to be especially compatible with D-400. No funny curve behavior, very stable, very easy to print negatives in every type of light.

I agree Delta 400 in DS-10 stock (9m at 20˚C), 1+1 (13.5m at 20˚C) or 1+2 (10m at 25˚C) work all very nicely. Generally speaking, I find DS-10 to be ideal as the general purpose fine grain developer for 400-speed films. It provides speeds no lower than D-76 and grain finer than D-76, often with slightly softer highlights. Other films I like with DS-10 are Neopan 400, Plus-X, Tri-X, HP5 Plus, T-MAX P3200 and Delta 3200. Based on my tests, other developers that provide this level of fine grain would also lose speed.

I prefer DS-12 or another developer for APX25, Pan F Plus, T-MAX 100 and Fuji Acros.

One peculiarity of Delta 400 is that it takes longer than many other films to fix. If the fixer is nearing exhaustion, it may clear other films in a couple of minutes, but Delta 400 may take forever.

 

[Ryuji]

They are generally lumped together because they are all 'monodisperse emulsions' or 'monosize crystal emulsions', that is, the crystal size is much more tighly controlled than with the old cubic-crystal emulsions. This inevitably means that they can be finer grained for a given speed (fewer big crystals) but it also means that they have less tolerance for over- or under-exposure (big grain in the former case, less shadow detail in the latter) AND a smaller developer repertoire with once again less tolerance of over- and under-development. The control, I believe, is achieved by 'double-jetting' the emulsion ingredients, that is, adding controlled quantities of A and B simultaneously instead of adding A to an excess of B.

The actual emulsion manufacturing is more complicated. A single film is usually coated in two layers, and each layer is a blend of multiple emulsions. Each emulsion component is most likely monodisperse grains separately sensitized. This is because grains of different size and shape require different quantities of sensitizing agents to be optimal.

T-grains (tabular grains) are, as their name suggests, big, flat crystals. They're also very thin, apparently enough so to reduce blue sensitivity -- photons can go straight through -- which accounts for the extra dye sensitization in T-grain.

Tabular grain structure does not reduce blue sensitivity. It just provides more surface area for the sensitizing dye to adsorb on. However, maximum level of dye may decrease blue sensitivity. The degree of this reduction depends on the dye and the grain structure. One effective way to maximize the total overall speed is to make multilayer core-shell tabular emulsion with the highest iodide layer just inside the outermost shell, with no iodide on the outermost shell.

Epitaxial is harder to understand, but as I recalll it essentially consists of growing one sort of crystal on the outside of another. Delta crystals are triangular (surprise!) and correctly exposed Delta emulsions are grainier than correctly exposed T-Grain BUT less grainy than over-exposed T-grain where all the development sites run together.

Epitaxial growth is usually made at the corners of each crystal. This is done to increase the efficiency with which captured photoelectrons give rise to a developable latent image center. Both Kodak and Fuji have this technology. However, I am not certain if this technology is widely used in commercial b&w emulsions.

One feature of old fashioned fast films is that they contained a lot of junk grains that have too low photographic speed (but they may dissolve in developer to facilitate physical development, to enlarge midtone grains), and also a few large grains that are very fast. Blending of several monodisperse emulsions separately sensitized to optimum level is a much better approach in realizing desirable sensitometric curve by design, not by the art. Also, since each grain is optimally sensitized, modern approach gives better speed-to-grain ratio. What I wrote in this paragraph applies to conventional emulsions made today as well.

Regarding differences among tabular grain products, a major difference comes from the blending strategy. The curve shape, etc. can be varied a lot in this stage. Then the internal structure of each tabular grain emulsion (the blend components) matters a lot. Depending on the locations of iodide layer, the site, number and type of crystalline defects (some are very useful and intentionally created!), diameter-to-thickness ratio, etc. Many of these factors modify the way the crystal is developed in the developer, and they play very important role in sensitometric curve as well as visual effects of the resulting image.

 

[Ryuji]

Sorry to be confrontational but Delta is not T-grain. They are very different technologies: tabular (T) versus epitaxial (Delta). As Ilford put it, "Our technology isn't necessarily better, but it is better behaved."

I would want to see Ilford's technical description of it, but I don't buy that argument. Making of tabular grain (or any modern emulsion) makes seed crystals and then enlarge them by growth stage. In the case of t-grain, the seed crystals have two twinned planes along which the crystal will grow by epitaxial growth. So, unless Ilford supplies better explanation, I would interpret what you said to mean the same thing as t-grain.

Note: the epitaxial growth I said in the previous response was referring to a different technique, which grows a different silver halide phase at one or more corners of each crystal after the base crystal of the desired size is obtained. The added epitaxy is very small compared to the base crystal size.

 

[RalphLambrecht]

This is not very common but quite possible. If your combination tests out this way and gives consistently good results, nothing wrong with that.

 

[pentaxuser]

Dear Pentaxuser,

Probably too late now! I'd be inclined to drop to 320 in ID-11 in contrasty lighting (which churches can be) and 250 or even 200 in Perceptol.

Cheers,

Rogee

Thanks for the very quick reply. Based on its transmission time it would have been in time. I did intend to check this morning but time ran away with me.

I opted for D100 Professional in the end and rated it at 80. Almost all available light shots were in hazy sun/slightly overcast conditions and for the rest I used flash.

I intend to develop in Perceptol. I think you suggested increasing dev time by 10% over that quoted by the manufacturer.

Unfortunately it seems that at EI 80 I have chosen a speed not quoted by Ilford who cover EI 50 or box speed. At EI 50 Ilford quotes 12 mins at 1+0 and 13 at 1+1 which at 10% extra would make it 13mins 12 secs or 14mins 20 secs respectively at EI 50.

Have I got it right and what should I calculate for EI 80?

Actually I am pretty sure that my incentive to rate films at other than box speed and in other than ID11 was a print in one of your books. I feel sure it was HP5+ at 320 in Perceptol. I later tried HP5+ at 250 in Perceptol and had the best negs and consequently prints I have ever had.

I have had less success with the Delta range but have yet to try it at less than box speed.

Pentaxuser

 

[joeyk49]

Dear Peter,

They are generally lumped together because they are all 'monodisperse emulsions' or 'monosize crystal emulsions', that is, the crystal size is much more tighly controlled than with the old cubic-crystal emulsions. This inevitably means that they can be finer grained for a given speed (fewer big crystals) but it also means that they have less tolerance for over- or under-exposure (big grain in the former case, less shadow detail in the latter) AND a smaller developer repertoire with once again less tolerance of over- and under-development ........

Roger

I can testify to this...I recently mislabeled some bulk loaded D400 as PanF+ and shot it at 50. After developing in Rodinal, I was surprized to find that I had some usable negatives. The grain was fairly large; my 5x7 enlargements looked about as grainy as D3200 would have looked (or, at least it seemed that way).

 

[Markok765]

..

 

[gnashings]

Dear Mr. Hicks,

Thanks for the explanation - it certainly sheds some light (no pun intended) on the differences between the two films. It also explains the difference in look between the two, accounting for my preference of Delta over Tmax - but also the ability of Tmax (especially 100) to give almost unreal sharpenss and fine grain - however clinical and lifeless the look ends up being in my hands.

I will from now on refer to them as "new technology films" and to all the TriX's, FP's and HP's as "traditional technology" - I think that's accurate enough for my general purposes.

Thanks,

Peter.

 

[Roger Hicks]

I would want to see Ilford's technical description of it, but I don't buy that argument.

Dear Ryuji,

Whether you buy it or not, the information given came from Mike Gristwood of Ilford (since the reorganization, he works elsewhere). We have had many conversations about such matters and he sent me a copy of a 64-page or so paper on monodisperse emulsions (not an internal Ilford document). He had no especial reason to lie; their 'core shell' technology is epitaxial on my understanding; and I have seen some of the electron micrographs of both T-grain and Delta, which I assume you have not.

You may well be right about the reason for the reduced blue sensitivity, but whatever the reason, it is there and measurable.

As I said, there would probably be those on the forum who knew more than I, but equally, I am aware of multi-layer coating of mixed monodisperse emulsions. There's just a limit to what you can get into one post.

Cheers,

Roger

 

[Ryuji]

You misread my post; I'm saying that all emulsions mainly consisting of tabular grain (or however they call it) can be called epitaxial grains. I don't know of any other practical way to make tabular core-shell grains without epitaxial process.

I make several kinds of silver halide emulsions, some of which are tabular grain. I am very familiar with the emulsion making process and of course I'm very familiar with how crystals of various crystalographic types look. I also strip (dissolve, to be precise) emulsions off some commercial products and examine their crystals and how they develop in particular developers.