Speed Increasing Dev Question

[Jed Freudenthal]

A speed increasing developer like Acufine or Microphen lets you expose the film at a higher speed than the box setting (i.e., it lets you "underexpose" in camera, but you're not really underexposing, because the speed is really higher), but still retain good shadow detail and normal contrast at the reduced exposure.

This differs from what people normally call "pushing" (attempting to increase film speed substantially by extending development time), which usually increases density in the highlights while not really improving shadow detail significantly, and film speed is measured in terms of shadow detail.

Good, there are always people who bring us back to the subject

And then I go back to the remarks of David Goldfarb (see quotation). David is absolutely right in his observation and remarks. Shadow detail in acufine e.g. has a different origin than shadow detail in a non-compensating developer. The acufine will add shadow detail and will not change the normal contrast. That sounds as straightforward language. [ The MTF story is just to clarify this; but the opposite might be the result; poor teachers ].

Jed

 

[Roger Hicks]

. Shadow detail in acufine e.g. has a different origin than shadow detail in a non-compensating developer. The acufine will add shadow detail and will not change the normal contrast.

Jed

Dear Jed,

Now we're back on track:

I am sure you know this, but others who read your post may not: ANY speed increasing developer (e.g. Microphen, DD-X) will increase shadow detail at a constant contrast.

In what sense has the shadow detail in a compensating developer a different origin from shadow detail in a non-compensating developer?

Cheers,

R.

 

[Jed Freudenthal]

Dear Jed,

Now we're back on track:

I am sure you know this, but others who read your post may not: ANY speed increasing developer (e.g. Microphen, DD-X) will increase shadow detail at a constant contrast.

In what sense has the shadow detail in a compensating developer a different origin from shadow detail in a non-compensating developer?

Cheers,

R.

Dear Roger:

Thanks to our danish friend, we are back on track. B.t.w where is Aquitaine? I am quite often in the Aquitaine in France; but is that where you are?

Anyway, I will try to clarify why a compensating developer like acufine will show the shadow detail better, without changing the contrast in the middle area. And then in non-scientific language. To that end we have to look at a shadow in the world around us. Or even better, look at the brightness (luminance) distribution in the middle area. You will notice, that the luminance in no spot is really the same as in the spot next to it.
The brightness is an ever changing in nature, from every spot to every spot.. And, it is the brightness (luminance) that we are recording on our film.
Now, when you look at the shadows, it is exactly the same as with the middle tones. It is possibly a little more difficult to observe, because it is darker, but there is a variety of brightnesses. Some are tiny, some are only a little brighter or darker than the surroundings. Anyway, a shadow area in nature is not an area of an uniform brightness, but a complex of many brightnesses.
Now, if you take a developer that can catch this complex picture of different brightnesses, you will get the complete richdom of the shadow in your image. Now, this is what a compensating developer does. Of course, it will add extras in the middle tones too; but this is less noticed.
With high quality lenses, the effect in the shadows is very pronounced, because tiny lighter spots in the shadows will show up.
A non compensating developer may have certain qualities, but not the quality to record all those details in the shadows ( and in the middle tones and highlights)

Jed

 

[Roger Hicks]

Dear Roger:

Thanks to our danish friend, we are back on track. B.t.w where is Aquitaine? I am quite often in the Aquitaine in France; but is that where you are?

Anyway, I will try to clarify why a compensating developer like acufine will show the shadow detail better, without changing the contrast in the middle area. And then in non-scientific language. To that end we have to look at a shadow in the world around us. Or even better, look at the brightness (luminance) distribution in the middle area. You will notice, that the luminance in no spot is really the same as in the spot next to it.
The brightness is an ever changing in nature, from every spot to every spot.. And, it is the brightness (luminance) that we are recording on our film.
Now, when you look at the shadows, it is exactly the same as with the middle tones. It is possibly a little more difficult to observe, because it is darker, but there is a variety of brightnesses. Some are tiny, some are only a little brighter or darker than the surroundings. Anyway, a shadow area in nature is not an area of an uniform brightness, but a complex of many brightnesses.
Now, if you take a developer that can catch this complex picture of different brightnesses, you will get the complete richdom of the shadow in your image. Now, this is what a compensating developer does. Of course, it will add extras in the middle tones too; but this is less noticed.
With high quality lenses, the effect in the shadows is very pronounced, because tiny lighter spots in the shadows will show up.
A non compensating developer may have certain qualities, but not the quality to record all those details in the shadows ( and in the middle tones and highlights)

Jed

Dear Jed,

The very north of the historic Aquitaine; near Thouars, the last city to fall to the French in the Hundred Years' War.

Either I am misunderstanding you grievously or your explanation of a compensating developer is at variance with the facts.

Shadow density in any given developer depends on exposure and development time. In order to remove the variable of development time, the original DIN standard specified development to gamma infinity and a fixed density of 0,10; the original Kodak/ASA standard specified a fractional gradient criterion; and the current ISO standard combines the two in a rather ingenious way with the fixed density and a gradient that is near enough 0,615.

Film speed (= shadow density under the specified contrast criteria) varies with developer. A speed increasing developer such as Ilford DD-X will give a true ISO speed of better than 650 with Ilford HP5 Plus. A fine grain developer may reduce the true speed to 250 or less. This is completely separate from any compensating effect.

Compensation is a means of allowing development to continue in the shadows while suppressing it in the highlights, by the simple means of exhausting the developer in the highlights. This 'pushes over' the shoulder of the D/log E curve, thereby inevitably compressing the differentiation of the mid-tones: the paper can only represent a log density range of about 2.2 maximum, 1.95 dynamic, so if a longer subject brightness range is represented in that print, the tones must be compressed one way or another.

There are three main ways of doing this: reduced development, softer paper, and compensating developer. The first two compress all tones more or less evenly; the last compresses the mid tones, thereby allowing better representation of both shadows and highlights, but always at the expense of the mid tones. It cannot be otherwise.

Let us now consider a big step wedge with widely spaced 1/10 stop gradations. A contrasty lens/camera system -- not necessarily the same thing as a lens with a high MTF at high frequencies -- will have less flare and is more likely to differentiate all the tones in the shadows. With a low-contrast system, flare will 'fill' the shadows, which will be accordingly more poorly rendered.

Now, perhaps what you are saying is that a compensating developer allows overdevelopment for a steeper toe (and hence better differentiation of closely separated shadow tones) without excessive highlight contrast. This is probably true with the right developer, but I would be astonished if the development in this case met ISO contrast conditions and, as I say, the mid-tones must be compressed, i.e. the curve becomes more S-shaped. Whether or not this is desirable will of course depend on the subject matter and brightness distribution. I would also be surprised, having plotted a number of D/log E curves in my time, if the increase in shadow detail were anything like as significant as the pushing-over of the shoulder.

A further complication is that increased agitation will raise toe speed at a given contrast (and therefore the ISO speed), while compensating developers necessarily rely on reduced agitation.

I would therefore argue that first, while a contrasty lens is very highly desirable, the 'relevant frequencies' which you mentioned but never defined can afford to be quite low, corresponding perhaps to 50-60 lp/mm, and second, that except for subject with a very long brightness range, a true speed increasing developer is vastly more useful than a compensating developer.

I apologize for the excessively long letter, and the somewhat combative tone of the second paragraph, but really, I cannot see your argument. I am not completely ignorant in this field, having started some 40 years ago and numbering among my friends and (more usually) acquaintances a number of people who are very knowledgeable indeed in various photographic fields. They know much more than I, but I must say that in many years of conversation and correspondence I have never been quite so perplexed by the arguments of somone apparently knowledgeable.

I'll end by straying (slightly) off-topic again, with something which a Zeiss lens designer once said to me: I think it was Dr. Hubert Nasse, but it was a good few years ago, so I'm not sure. It seems to me to cut to the centre of this discussion, and to apply to most of photography. I paraphrase from memory:

"You can design a lens, and computer-simulate it, and think you know everything about it, but until you build it, you won't know how it performs. And even when you have built it, you can't quantify everything about it. Every lens has its own look..."

Cheers,

R.

 

[Jed Freudenthal]

Dear Jed,

The very north of the historic Aquitaine; near Thouars, the last city to fall to the French in the Hundred Years' War.

Either I am misunderstanding you grievously or your explanation of a compensating developer is at variance with the facts.

Shadow density in any given developer depends on exposure and development time. In order to remove the variable of development time, the original DIN standard specified development to gamma infinity and a fixed density of 0,10; the original Kodak/ASA standard specified a fractional gradient criterion; and the current ISO standard combines the two in a rather ingenious way with the fixed density and a gradient that is near enough 0,615.

Film speed (= shadow density under the specified contrast criteria) varies with developer. A speed increasing developer such as Ilford DD-X will give a true ISO speed of better than 650 with Ilford HP5 Plus. A fine grain developer may reduce the true speed to 250 or less. This is completely separate from any compensating effect.

Compensation is a means of allowing development to continue in the shadows while suppressing it in the highlights, by the simple means of exhausting the developer in the highlights. This 'pushes over' the shoulder of the D/log E curve, thereby inevitably compressing the differentiation of the mid-tones: the paper can only represent a log density range of about 2.2 maximum, 1.95 dynamic, so if a longer subject brightness range is represented in that print, the tones must be compressed one way or another.

There are three main ways of doing this: reduced development, softer paper, and compensating developer. The first two compress all tones more or less evenly; the last compresses the mid tones, thereby allowing better representation of both shadows and highlights, but always at the expense of the mid tones. It cannot be otherwise.

Let us now consider a big step wedge with widely spaced 1/10 stop gradations. A contrasty lens/camera system -- not necessarily the same thing as a lens with a high MTF at high frequencies -- will have less flare and is more likely to differentiate all the tones in the shadows. With a low-contrast system, flare will 'fill' the shadows, which will be accordingly more poorly rendered.

Now, perhaps what you are saying is that a compensating developer allows overdevelopment for a steeper toe (and hence better differentiation of closely separated shadow tones) without excessive highlight contrast. This is probably true with the right developer, but I would be astonished if the development in this case met ISO contrast conditions and, as I say, the mid-tones must be compressed, i.e. the curve becomes more S-shaped. Whether or not this is desirable will of course depend on the subject matter and brightness distribution. I would also be surprised, having plotted a number of D/log E curves in my time, if the increase in shadow detail were anything like as significant as the pushing-over of the shoulder.

A further complication is that increased agitation will raise toe speed at a given contrast (and therefore the ISO speed), while compensating developers necessarily rely on reduced agitation.

I would therefore argue that first, while a contrasty lens is very highly desirable, the 'relevant frequencies' which you mentioned but never defined can afford to be quite low, corresponding perhaps to 50-60 lp/mm, and second, that except for subject with a very long brightness range, a true speed increasing developer is vastly more useful than a compensating developer.

I apologize for the excessively long letter, and the somewhat combative tone of the second paragraph, but really, I cannot see your argument. I am not completely ignorant in this field, having started some 40 years ago and numbering among my friends and (more usually) acquaintances a number of people who are very knowledgeable indeed in various photographic fields. They know much more than I, but I must say that in many years of conversation and correspondence I have never been quite so perplexed by the arguments of somone apparently knowledgeable.

I'll end by straying (slightly) off-topic again, with something which a Zeiss lens designer once said to me: I think it was Dr. Hubert Nasse, but it was a good few years ago, so I'm not sure. It seems to me to cut to the centre of this discussion, and to apply to most of photography. I paraphrase from memory:

"You can design a lens, and computer-simulate it, and think you know everything about it, but until you build it, you won't know how it performs. And even when you have built it, you can't quantify everything about it. Every lens has its own look..."

Cheers,

R.

Dear Roger,

Interesting to note, you are living in the French Aquitaine. My brother, and his family are living there too. ( Portets, Bordeaux and Toulouse). So I am in the Aquitaine from time to time. Just two months ago I was there, and I got some wine in my cubitainers.

Let our first staring point be the remark of David, that it is possible to get better shadow detail using a developer like acufine. And I agree with that. The question is: what is the explanation. My answer is: you cannot explain it in a sensitometric way. THis is a macroreproduction. One cannot apply it to a developer like acufine. Such a developer has a microreproduction. Hans Windisch, in his famous book 'New Photo School' has described already in the 1930 th how to deal with this phenomenon. I would think, this is enough for the average photographer ( certainly for David).
Another question is the explanation of this phenomenon. And, I think it is very hard to give an explanation without getting involved in scientific matters.
The best thing is, I would say, try a compensating (or High Definition) developer and look at the result. The result is, what counts. There are quite a number of that kind of developers around. Acufine is a commercially available one, and I have published on the APUG site a few recipes of my own. In the Netherlands, we have made comparisons between the developers in a workshop which was held last fall.

Jed

 

[Roger Hicks]

My answer is: you cannot explain it in a sensitometric way. THis is a macroreproduction. One cannot apply it to a developer like acufine.
Jed

Dear Jed,

If you can't explain it in a sensitometric way, i.e. draw the D/log E curve, you can't explain it scientifically, and we are back to Dr. Nasse's observations -- which rather discounts your observations about MTF, etc., as we then agree that the answer is (in the English vernacular) 'Suck it and see'.

Cheers,

R.

 

[Jed Freudenthal]

Dear Jed,

If you can't explain it in a sensitometric way, i.e. draw the D/log E curve, you can't explain it scientifically, and we are back to Dr. Nasse's observations -- which rather discounts your observations about MTF, etc., as we then agree that the answer is (in the English vernacular) 'Suck it and see'.

Cheers,

R.

Dear Roger,
In sensitometry, one has the relationship between luminance and density. But, this does not mean that you are allowed to apply this relation anywhere. C.N. Nelson has indicated where you can apply sensitometric principles and gives a few examples, where not. [ 'The theory of the photographic process, 4 th ed, ed T.H. James]. See page 560, starting with : A tone reproduction curve is a description of the microreproduction, not the microreproduction characteristics of the photograph'.....
I hope you have this classical standard text availble; it is quite a job to retype the whole text.
It is like in mathematics: when you need a description with negative or rational numbers , the numbers 1,2,3... are not enough anymore. Or in painting; you cannot make an oil painting, when you have water colors only.
Or, in the Zeiss example. They have much under control in their theories, but not everything. And no wonder; perception is important in photography. But, perception is psychologically controlled. The psychologists are trying to get that part under control, using MTF.
But, we have to becareful not to go in many interesting areas. Keep an eye on the original question.

Jed

 

[Roger Hicks]

Keep an eye on the original question.

Jed

I hesitate to appear rude, but until your first post in this topic, that's what everyone did. I pointed out several errors in your analysis -- some of which corrections you do not seem to have disputed -- and things went down hill from there.

Cheers,

R.

 

[Jed Freudenthal]

Speed increasing developers

I hesitate to appear rude, but until your first post in this topic, that's what everyone did. I pointed out several errors in your analysis -- some of which corrections you do not seem to have disputed -- and things went down hill from there.

Cheers,

R.

Dear Roger,
The subject of this thread is speed increasing developers. David Goldfarb mentioned a few compensating developers developers with that property ( and he defined it via an increase in detailed shadow). Soeren mentioned another example. I agree with their point of view, and added literature references, to support the thesis. Moreover, within APUG we made comparative tests to proof the speed increasing property.
If you do not agree with this point of view, I would rather say: it is your turn to proof your view. Up to now I have not seen anything like that.
In my opinion, it is a question of terminology. 'Speed increasing developers' is used by photographers for a long time to indicate an increase in shadow detail. It is a practical photographic approach.
The increase of (ASA) speed is possible by modifications of a film, not by developers. It is the field of film producers.

Jed

 

[Soeren]

Dear Roger,
Snip
'Speed increasing developers' is used by photographers for a long time to indicate an increase in shadow detail. It is a practical photographic approach.
The increase of (ASA) speed is possible by modifications of a film, not by developers. It is the field of film producers.

Jed

Ehh ASA/ISO well ok thats the boxspeed right? how about EI (exposure Index)
It is common knowledge that the effective speed or EI of a film is reduced in Perceptol compared to D76 isn't it? And the EI is for that film is higher if developed in Microphen/DDX? Reading this thread is confusing me. I really should let it go
Cheers
Søren

 

[jim appleyard]

Ehh ASA/ISO well ok thats the boxspeed right? how about EI (exposure Index)
It is common knowledge that the effective speed or EI of a film is reduced in Perceptol compared to D76 isn't it? And the EI is for that film is higher if developed in Microphen/DDX? Reading this thread is confusing me. I really should let it go
Cheers
Søren

Correct. There is only one ISO, your box speed, but many EI's. Your EI, and I stress YOUR, depends on subject matter, how you meter (in-camera, spot, incedent {sp?} and how accurate they are), developer, developer dilution, type of enlarger and what type of print you like to make, etc.

 

[varjag]

Different developers have different efficiency, and can give different effective ISO speed to film. Box speed for classic BW film means just a practical average from manufacturer's point of view, typically in something like D-76, and indeed can be vaired to either side with changes in development. Unless you have strictly limited processing options (developer formulation, processing time, agitation, temperatures), like in E6 or C41 processes, true film speed can vary and be affected by development.

 

[Jed Freudenthal]

Correct. There is only one ISO, your box speed, but many EI's. Your EI, and I stress YOUR, depends on subject matter, how you meter (in-camera, spot, incedent {sp?} and how accurate they are), developer, developer dilution, type of enlarger and what type of print you like to make, etc.

This is exactly what it is.

Jed

 

[haris]

OK, I never understod it...

I do understand in theory what you are saying, but what that means in practice? For example:

I shoot ISO 100 film with particular developer. There is written that if develop it for 6 minuter I will get speed of ISO 100, and if develop it 8 minutes I will get speed of ISO 200. Is that practically means that if I shoot film at ISO 100 I develop it for 6 minutes, and if I shoot it at ISO 200 I develop it for 8 minutes. That is how I understand it.

Or that means I shoot film at ISO 100 and during developing I increase its speed. I don't see usefulness of that, and don't understand if that is issue.

What is use for shooting film at one ISO and increase its speed during developing? I understand if I have ISO 100 film, but it is dark for ISO 100 and I use it as ISO 200 film (set meter as ISO 200 film) and develop it 8 instead 6 minutes.

What is reason to have light for ISO 100 film, shoot film as ISO 100 film, and during developing develop it as ISO 200 film that is increase its speed during developimg, not during shooting.

I simply don't get it...

 

[varjag]

Haris, what you talking about is commonly referred as "pushing". Say you have developer D1, which gives ISO speed 100 to particular film F with processing time of 6 minutes. When you rate film F for speed of 200 (or in proper terminology use exposure index, or EI, of 200) and process the film for 8 minutes in D1 you do not increase ISO speed, but underexpose and overdevelop. This doesn't bring you any more detail in the shadows and increases contrast, bringing midtones out to printable levels.

However, same film F may give true ISO speed of 200 in developer D2, or ISO 50 in developer D3.

 

[haris]

Haris, what you talking about is commonly referred as "pushing". Say you have developer D1, which gives ISO speed 100 to particular film F with processing time of 6 minutes. When you rate film F for speed of 200 (or in proper terminology use exposure index, or EI, of 200) and process the film for 8 minutes in D1 you do not increase ISO speed, but underexpose and overdevelop. This doesn't bring you any more detail in the shadows and increases contrast, bringing midtones out to printable levels.

However, same film F may give true ISO speed of 200 in developer D2, or ISO 50 in developer D3.

Thank you. So, this is clear. Ok, now, what is practical reason for increasing film speed. What is reason to shoot film at speed let say ISO 100 and increase its sped with developing? In fact what is increasing speed with developing?

I mean: I shoot HP5 and set meter for ISO400(or other speed which I think is film "real" speed, but for making thing simple let say its real speed is ISO400) and have ID11. And in booklet (or I find out, but again to make things simpler) says for HP5 in ID11 developing if light is metered as for ISO400 film is 8 minutes. So, there we have film's real speed and correct developing for film's real speed. But, then there says that for HP5 in Microphen developing time of 10 minutes will give ISO800, even if I shoot it as ISO 400, real speed, film. What I will get if I shoot HP5 metered at ISO400 and develop it 10 minutes in Microphen instead 8 minutes in ID11, that is why there are reasons for getting ISO800 with developing of film which was shooted as ISO400 film? Why not shoot that film at ISO800?

Or, that means I can shoot HP5 metering light as for ISO800 film, develop it in Microphen for 10 minutes, and will have same "quality" of tone scale as if I shooted HP5 as ISO400 and developed it in ID11 for 8 minutes.

So, if that is case, why then HP5 is refferd as ISO400 film, and not as ISO800?

(All times are just as examples not real developing times)

Sorry, but I never understood that.

 

[Roger Hicks]

The increase of (ASA) speed is possible by modifications of a film, not by developers. It is the field of film producers.

Jed

Dear Jed,

I am sorry, this is simply not the case.

True ISO speeds are determined by the exposure needed to give a density of 0,10 above fb+f under ISO contrast conditions. Depart from ISO conditions and you have an EI, not an ISO speed, but as long as you develop to ISO contrast and measure the ISO speed point, you have an ISO speed, which can vary. As a rule of thumb you can, by choice of developer, add up to about 1 stop or wipe off a stop or more. Thus the ISO speed of an 'ISO 400' film can easily vary from ISO 200 to ISO 650 or a little more.

This is sufficiently commonplace among anyone who understands the subject and knows what ISO means that it hardly requires justification: it's taken for granted, which is why it rarely appears in the literature. The first example that springs to mind is Foma's instruction sheet for Fomapan 200, where it is clear from the D/log E curves that the film is only ISO 200 in a speed-increasing developer -- and barely, even then.

Or look at a Kodak data sheet: I quote from FY-2 issue H: 'D-25 Extra-fine-grain developer -- This developer necessitates an exposure increase of 50 to 100 per cent'.

Or from Ilford Data Sheet P10.5: "Special developers have been formulated to produce images of reduced graininess. Many of these developers restrict grain size by dissolving some of the silver forming the image. Since this causes a reduction in density a longer exposure is needed to achieve a satisfactory density for printing ." They then go on to say that with Ilford Microphen developer "A speed increase of at least 50 per cent is possible with most materials..."

Most manufacturers choose a 'middle of the road' developer for speed determination, as it gives the best balance of speed, grain and sharpness. More speed = coarser grain (and sometimes lower sharpness), finer grain = lower speed (and often lower sharpness). You can't get something for nothing.

If speed were constant, why would anyone use anything other than a fine-grain developer for speed determination? Why do you think there used to be a standard ANSI/ASA developer? And why do you think that current ISO standards require the manufacturer to state what developer they used? There can only be one answer to all these questions: different developers affect speed. True speed, under ISO conditions, not 'pushing' or 'pulling'. Agitation is specified for the same reason: more agitation = a higher toe speed.

Have you ever plotted a D/log E curve? Because if you can, it's pretty easy to see that true film speed is indeed affected by developer choice. Expose two rolls of the same film identically. Process one in Perceptol and one in DD-X or Microphen, to ISO contrast. Plot the curves. Superimpose them. They will diverge most at the base, because that's where the speed increase is determined. If the curves are not parallel (and at the ISO standard slope), adjust your development times until they are. When you've done that, to remind yourself how it works, go back to the films and take densitometer readings of identically exposed areas. The ones in the speed increasing developer will be denser...

You clearly know a great deal less about this than you think you do. You started out by trying to blind me with science and MTF curves. That failed, because what you were saying did not make sense, so you switched to saying that science can't tell us everything: an impressive change of ground. Now you are simply departing from the truth. Developers DO affect ISO speeds, and I am somewhat exasperated by the time it has taken to try to explain this to someone who clearly knows very little about the subject and is unwilling to learn.

Cheers,

Roger

 

[Jed Freudenthal]

Dear Jed,

I am sorry, this is simply not the case.

True ISO speeds are determined by the exposure needed to give a density of 0,10 above fb+f under ISO contrast conditions. Depart from ISO conditions and you have an EI, not an ISO speed, but as long as you develop to ISO contrast and measure the ISO speed point, you have an ISO speed, which can vary. As a rule of thumb you can, by choice of developer, add up to about 1 stop or wipe off a stop or more. Thus the ISO speed of an 'ISO 400' film can easily vary from ISO 200 to ISO 650 or a little more.

This is sufficiently commonplace among anyone who understands the subject and knows what ISO means that it hardly requires justification: it's taken for granted, which is why it rarely appears in the literature. The first example that springs to mind is Foma's instruction sheet for Fomapan 200, where it is clear from the D/log E curves that the film is only ISO 200 in a speed-increasing developer -- and barely, even then.

Or look at a Kodak data sheet: I quote from FY-2 issue H: 'D-25 Extra-fine-grain developer -- This developer necessitates an exposure increase of 50 to 100 per cent'.

Or from Ilford Data Sheet P10.5: "Special developers have been formulated to produce images of reduced graininess. Many of these developers restrict grain size by dissolving some of the silver forming the image. Since this causes a reduction in density a longer exposure is needed to achieve a satisfactory density for printing ." They then go on to say that with Ilford Microphen developer "A speed increase of at least 50 per cent is possible with most materials..."

Most manufacturers choose a 'middle of the road' developer for speed determination, as it gives the best balance of speed, grain and sharpness. More speed = coarser grain (and sometimes lower sharpness), finer grain = lower speed (and often lower sharpness). You can't get something for nothing.

If speed were constant, why would anyone use anything other than a fine-grain developer for speed determination? Why do you think there used to be a standard ANSI/ASA developer? And why do you think that current ISO standards require the manufacturer to state what developer they used? There can only be one answer to all these questions: different developers affect speed. True speed, under ISO conditions, not 'pushing' or 'pulling'. Agitation is specified for the same reason: more agitation = a higher toe speed.

Have you ever plotted a D/log E curve? Because if you can, it's pretty easy to see that true film speed is indeed affected by developer choice. Expose two rolls of the same film identically. Process one in Perceptol and one in DD-X or Microphen, to ISO contrast. Plot the curves. Superimpose them. They will diverge most at the base, because that's where the speed increase is determined. If the curves are not parallel (and at the ISO standard slope), adjust your development times until they are. When you've done that, to remind yourself how it works, go back to the films and take densitometer readings of identically exposed areas. The ones in the speed increasing developer will be denser...

You clearly know a great deal less about this than you think you do. You started out by trying to blind me with science and MTF curves. That failed, because what you were saying did not make sense, so you switched to saying that science can't tell us everything: an impressive change of ground. Now you are simply departing from the truth. Developers DO affect ISO speeds, and I am somewhat exasperated by the time it has taken to try to explain this to someone who clearly knows very little about the subject and is unwilling to learn.

Cheers,

Roger

Dear Roger,

First off all, I developed (scientific) film emulsions as part of my profession. I had a microdensitometer, and we did in the laboratory HD as well as MTF.
When I read your remarks right, and I did that a few times again, I read hat the practical speed, the EI, or whatever you want to name it, developer dependent is. So, what are we talking about?:confused:
I have been member of many standardization committees, and the starting point is to have an unique result, based an accurately defined conditions. And that is in the ISO standard also the case.
The two situations are incomparable, as has been said by other people and me in this thread.
I use the ISO number on a film box just as a reference point, or starting point. What I really use depends on the situation ( the developer is just one). In the case of a HD developer, it might even change from one photograph to the other. It will depend on the light distribution in the deep shadows ( this is the interpretaion from the artistic point of view, and called the black compression).


Jed

 

[Roger Hicks]

Dear Roger,

First off all, I developed (scientific) film emulsions as part of my profession. I had a microdensitometer, and we did in the laboratory HD as well as MTF.
When I read your remarks right, and I did that a few times again, I read hat the practical speed, the EI, or whatever you want to name it, developer dependent is. So, what are we talking about?:confused:
I have been member of many standardization committees, and the starting point is to have an unique result, based an accurately defined conditions. And that is in the ISO standard also the case.
The two situations are incomparable, as has been said by other people and me in this thread.
I use the ISO number on a film box just as a reference point, or starting point. What I really use depends on the situation ( the developer is just one). In the case of a HD developer, it might even change from one photograph to the other. It will depend on the light distribution in the deep shadows ( this is the interpretaion from the artistic point of view, and called the black compression).


Jed

Dear Jed,

With all due respect, your reply addresses none of the points I mention.

I have never served on an ISO committee. One of my friends (Mike Gristwood) was however on the photographic ISO standards committee, until he left Ilford. Much of what I know -- and of what I have said in this thread -- comes from discussing with Mike the things I have read over the last 40 years.

I suspected that you had some peripheral knowledge of the subject, and I was right -- but scientific emulsions are not the same as pictorial emulsions. As you clearly illustrate, expertise in one ISO standard is no indicator of knowledge of, let alone expertise in, any other. From your replies, I find it hard to believe that you know very much about the ISO film speed standard.

You asked for supporting literature; I quoted some that was to hand. I also suggested a simple experiment that will confirm what I said: one that should be easy for you, with your access to densitometers and microdensitometers. What more do you want?

Perhaps you could answer a simple question:

Do you accept (or not) that ISO speeds -- not (in your patronising phrase) 'EIs or whatever I want to call them' but actual ISO speeds -- can be made to vary by choice of developer?

If yes, I consider myself vindicated. If no, then you are simply at variance with all the published literature and experimental fact, and there is little point in continuing.

I have no wish to appear rude, but most of what you have said in this thread is wrong, opaque or confusing -- sometimes all three. You have also changed your ground repeatedly, which is often the sign of someone with no supportable argument. I apologize for such blunt language, but I do not see any other way of conveying the strength of my disagreement.

Cheers,

Roger

 

[varjag]

What is reason to shoot film at speed let say ISO 100 and increase its sped with developing? In fact what is increasing speed with developing?

First you need to distinguish between "ISO speed" and "Exposure Index". They are sometimes used loosely but in general are not interchangeable.

To recur, when for film F in developer D1 you have ISO speed of 100, but expose it for 200 and increase processing time, you do not make it ISO 200. You use EI 200, but the film's true speed in the developer is still 100. In effect you underexpose and overdevelop, i.e. push film.

The main purpose of pushing is getting something printable from out of unfavorable light conditions.

But, then there says that for HP5 in Microphen developing time of 10 minutes will give ISO800, even if I shoot it as ISO 400, real speed, film.

No, you shall shoot it at EI 800, which in this case matches true speed of the film in Microphen. If the datasheet is correct, you will have same amount of shadow detail at reference contrast as you would with HP5 in ID11 shot at EI 400. You just need twice less light to achieve that, and that is a speed enchancement.

If you shoot it at EI 400 and process in Microphen as suggested, you will overexpose film 1 stop.

What I will get if I shoot HP5 metered at ISO400 and develop it 10 minutes in Microphen instead 8 minutes in ID11, that is why there are reasons for getting ISO800 with developing of film which was shooted as ISO400 film? Why not shoot that film at ISO800?

Mainly because relatively few developers match Microphen for film speed. D-76 (or ID11 if you like) has been the most common developer for decades, and if film would not achieve box speed in D-76 most people would consider it bogus, bordering to false advertisement.

Some manufacturers still do tricks like that however.

Or, that means I can shoot HP5 metering light as for ISO800 film, develop it in Microphen for 10 minutes, and will have same "quality" of tone scale as if I shooted HP5 as ISO400 and developed it in ID11 for 8 minutes.

Not entirely, because there are other factors in development aside from ISO speed. Different developers may e.g. have or not have compensating effect, and render distinctively different grain pattern, which all would affect visual perception of final image. This is why arriving at film/developer/EI combination remains very individual thing, and all suggestions (including datasheets) should serve mainly as starting points.

 

[haris]

First you need to distinguish between "ISO speed" and "Exposure Index". They are sometimes used loosely but in general are not interchangeable.

To recur, when for film F in developer D1 you have ISO speed of 100, but expose it for 200 and increase processing time, you do not make it ISO 200. You use EI 200, but the film's true speed in the developer is still 100. In effect you underexpose and overdevelop, i.e. push film.

The main purpose of pushing is getting something printable from out of unfavorable light conditions.


No, you shall shoot it at EI 800, which in this case matches true speed of the film in Microphen. If the datasheet is correct, you will have same amount of shadow detail at reference contrast as you would with HP5 in ID11 shot at EI 400. You just need twice less light to achieve that, and that is a speed enchancement.

If you shoot it at EI 400 and process in Microphen as suggested, you will overexpose film 1 stop.


Mainly because relatively few developers match Microphen for film speed. D-76 (or ID11 if you like) has been the most common developer for decades, and if film would not achieve box speed in D-76 most people would consider it bogus, bordering to false advertisement.

Some manufacturers still do tricks like that however.


Not entirely, because there are other factors in development aside from ISO speed. Different developers may e.g. have or not have compensating effect, and render distinctively different grain pattern, which all would affect visual perception of final image. This is why arriving at film/developer/EI combination remains very individual thing, and all suggestions (including datasheets) should serve mainly as starting points.

Thank you varjag.

So, if I understand correctly, thing is next:

I shoot HP5 as ISO (EI) 400, develop it in ID11 as ISO400 film, and for example getting images which are not printable because in this light conditions and developing method scene is too dark for getting quality prints. But, if under same shooting condition I develop HP5 in Microphen for getting ISO800, I will get images which will be printable with acceptable quality.

Thanks again for answers

 

[varjag]

I shoot HP5 as ISO (EI) 400, develop it in ID11 as ISO400 film, and for example getting images which are not printable because in this light conditions and developing method scene is too dark for getting quality prints. But, if under same shooting condition I develop HP5 in Microphen for getting ISO800, I will get images which will be printable with acceptable quality.

Now, careful here: if you process your film for its true speed in particular developer (say ISO 400), but get unprintable results it means your exposure was wrong. In your first case, if you set shutter speed and aperture combination according to amount of light available and film speed of ISO 400 you can expect good results. And in the second case, if you set shutter speed and aperture combination according to amount of light available and film speed of ISO 800 you can expect equally good results (modulo the difference in granularity and tonality). The difference is of course that in 2nd case you need twice less light available.

To re-iterate, using a speed enchancing developer is not the same as pushing. Pushing does not give you a faster film speed, it only makes mid-tones on negative dense enough to be printed or scanned.

 

[Jed Freudenthal]

Dear Jed,

With all due respect, your reply addresses none of the points I mention.

I have never served on an ISO committee. One of my friends (Mike Gristwood) was however on the photographic ISO standards committee, until he left Ilford. Much of what I know -- and of what I have said in this thread -- comes from discussing with Mike the things I have read over the last 40 years.

I suspected that you had some peripheral knowledge of the subject, and I was right -- but scientific emulsions are not the same as pictorial emulsions. As you clearly illustrate, expertise in one ISO standard is no indicator of knowledge of, let alone expertise in, any other. From your replies, I find it hard to believe that you know very much about the ISO film speed standard.

You asked for supporting literature; I quoted some that was to hand. I also suggested a simple experiment that will confirm what I said: one that should be easy for you, with your access to densitometers and microdensitometers. What more do you want?

Perhaps you could answer a simple question:

Do you accept (or not) that ISO speeds -- not (in your patronising phrase) 'EIs or whatever I want to call them' but actual ISO speeds -- can be made to vary by choice of developer?

If yes, I consider myself vindicated. If no, then you are simply at variance with all the published literature and experimental fact, and there is little point in continuing.

I have no wish to appear rude, but most of what you have said in this thread is wrong, opaque or confusing -- sometimes all three. You have also changed your ground repeatedly, which is often the sign of someone with no supportable argument. I apologize for such blunt language, but I do not see any other way of conveying the strength of my disagreement.

Cheers,

Roger

Dear Roger,
An ISO speed is given for a specified developer, under specified conditions.
If your conditions or developer is different. the rersult will be different. That is why there are so many different developers around. With certain one will get better shadow detail e.g. With other developers, the grain will be finer, and 35 mm users might use those developers. Any photographer can make its own choice, and the choice will usually depend on the camera he is using and the subject he is photographing.

So, I accept the ISO values, but only under the conditions for which they are valid. Those conditions can be found in the relevant ISO standard publication.
I think, you will not find many photographers following the ISO conditions. Therfore we use E.I. , based on own experience.

I have the impression that I (and others in this thread) reformulate the subject over and over. Therfore, I propose not to go ahead with is for the moment. I promise to come back, when we have new results on the subject within the Dutch APUG group.


Jed

 

[Roger Hicks]

Dear Roger,
An ISO speed is given for a specified developer, under specified conditions.

Dear Jed,

Precisely. And under the current ISO standard, ANY DEVELOPER MAY BE SPECIFIED. There is no longer a standard ISO developer.

The choice of developer affects the speed.

Now which bit do you disagree with?

Cheers,

R.

 

[Keith Tapscott.]

Under the current ISO standard, ANY DEVELOPER MAY BE SPECIFIED. There is no longer a standard ISO developer.
The choice of developer affects the speed.

Ilford`s technical data sheets usually mention the use of ID-11 for the ISO of their films, based on practical evaluation and not foot speed as is the ISO standard. I`m not sure which developer(s) are used for speed evaluation by other manufacturers, but I have a book called "Photographic Sensitometry" by Hollis N Todd & Richard D Zakia. On page 47, there is mention of the use of a developer for the American Standard PH 2.5-1960 of which the formula is:

Air-Free distilled water = 500ml
Metol developing agent = 1.0 g
Sodium Sulphite ( anhydrous ) = 25.0 g
Hydroquinone = 2.0 g
Sodium Carbonate ( anhydrous ) = 3.0 g
Potassium Bromide = 0.38 g
More air-free distilled water to make 1 litre.

As said, any developer may be specified and the developer type will have an effect on yield, e.g. speed, grain etc although it may be less confusing if the manufacturers would agree on an ISO testing standard formula, something which I doubt will ever happen.
:confused: