A general question on film development.

[Ian Grant]

If you use a different process or different developer than the factory, that doesn't magically change the ISO speed of the film. The film's speed is the same. I just don't understand the logic of people who think that the film's speed is changing when their metering or processing is changing. No, the film's speed isn't going anywhere; your metering and processing are. /QUOTE]

Unfortunately it does, the choice & balance of developing agents is extremely critical.

So a developer like Perceptol/Microdol-X cuts film speed by a stop, but a Phenidone/Hydroquinone developer like ID-68/Microphen increases speed by over half a stop.

Some super fine grain developers can reduce speed by 2-4 stops, needless to say they have gone out of use

Ian

 

[BetterSense]

So a developer like Perceptol/Microdol-X cuts film speed by a stop

I don't see it that way. Perceptol/Microdol-X may put 1 stop less density on the film than D76, but I don't see how that changed the film's speed. All it means is that you need to expose 1 stop more if you are using Perceptol. It doesn't mean the film speed magically changed. A film's speed is a property of its manufacture.

I know that if I expose a certain way, I will get probably a good stop more shadow density out of Tri-X if I develop it in Xtol than if I develop it in D23, but I don't think that developing in D23 somehow changes the film speed. Tri-X is an ISO 400 speed film, in any developer you use, period, if you believe Kodak (and there's no reason to doubt them). That's the point of standards.

Suppose Diafine, D76, and D23 are all exactly 1 stop apart in the amount of shadow detail they give HP5. Suppose Diafine gives 1 stop more shadow detail and D23 gives 1 stop less shadow detail than D76. It's muddled thinking to say "HP5 is a 400 speed film in D76, a 200 speed film in D23, and a 800 speed film in Diafine". No, it's a 400 speed film, period. If it transformed into an 800 speed film in Diafine, it would have TWO stops more shadow density when you developed it in Diafine!

 

[RalphLambrecht]

If you use a different process or different developer than the factory, that doesn't magically change the ISO speed of the film. The film's speed is the same. I just don't understand the logic of people who think that the film's speed is changing when their metering or processing is changing. No, the film's speed isn't going anywhere; your metering and processing are. ...

It doesn't change the ISO speed, but it changes your personal speed (EI) of the film in question.

... On the other side of the coin, I don't understand the value of knowing the film's exact speed, because all that matters is your results. ...

Knowing the EI of the film is away to get there.

... But if you ever want to know what it is, it's printed on the box. ...

ISO vs EI.

... I don't understand the advantage of re-rating the film speed, as if the film manufacturer does a poor job at it. ...

They don't do a poor job at it, but they have no chance of knowing what you do with it or what your photographic intent is (fine-art, reportage, forensic: all different exposure needs). The box speed is a general recommendation, nothing more. Use it as a starting point and modify it from there. Most fine-art photographers rate their film at 2/3 f/stop below box speed for a reason. They want more shadow detail!

 

[RalphLambrecht]

I don't see it that way. Perceptol/Microdol-X may put 1 stop less density on the film than D76, but I don't see how that changed the film's speed. All it means is that you need to expose 1 stop more if you are using Perceptol. If you had developed it in D76 instead, it would have more shadow density...see, the speed didn't change.

I know that if I expose a certain way, I will get probably a good stop more shadow density out of Tri-X if I develop it in Xtol than if I develop it in D23, but I don't think that developing in D23 somehow changes the film speed. Tri-X is an ISO 400 speed film, in any developer you use, period, if you believe Kodak (and there's no reason to doubt them). That's the point of standards.

BetterSense

That's just another way of saying that there is an ISO speed and a personal speed. Different way of looking at it but still the same concept.

 

[Thomas Bertilsson]

If you use a different process or different developer than the factory, that doesn't magically change the ISO speed of the film. The film's speed is the same. I just don't understand the logic of people who think that the film's speed is changing when their metering or processing is changing. No, the film's speed isn't going anywhere; your metering and processing are.

On the other side of the coin, I don't understand the value of knowing the film's exact speed, because all that matters is your results. But if you ever want to know what it is, it's printed on the box. I don't understand the advantage of re-rating the film speed, as if the film manufacturer does a poor job at it. But then, I don't really use light meters either, so maybe I should leave the film-testers and densitometrists alone to do their thing.

Film ISO speed is a pretty useless denomination for photographers is my take on it.
In order to yield optimum results with a film, there are so many variables in how we treat the film - in varying lighting conditions - than the film manufacturers do.
So we must gain experience of what to do with the film ourselves, regardless of what the silly box the film comes in says.
So I shoot TMax 250, Plus-X 80, and Acros 64. That's my starting point for normal exposure in MY process. Some lighting conditions require more exposure, others less, and that changes how the film is developed too.
If I want easily printed negs, that is. If I rate TMY-2 at EI 400 in normal lighting I struggle more when I print. Simple as that.

To each their own. It's all about developing good processes for our own working methods in the end, regardless of what everybody else says, including the people that manufactured it.

 

[RalphLambrecht]

What does "better tonality" mean?

Tonality is defined as 'the range of tones'. Giving more exposure and reducing development will increase the range of usable tones, and hence, increase tonality. I guess, you could call that 'better tonality'.

 

[MaximusM3]

Tonality is defined as 'the range of tones'. Giving more exposure and reducing development will increase the range of usable tones, and hence, increase tonality. I guess, you could call that 'better tonality'.

That's technically correct, Ralph, but since this is all very subjective, "better" may not be applicable. Giving more exposure and increasing development decreases the range of tones but that doesn't make them any less usable. Different, yes, but certainly not less usable. Again, taking Ralph Gibson as an example, one would have to say that his work is not about "better tonality" but HIS approach worked successfully nonetheless. There something to be said about a bold image that falls outside the norm to be interesting versus one that is 100% "correct" but falls flat on its face.

Best,

Max

 

[Ian Grant]

I don't see it that way. Perceptol/Microdol-X may put 1 stop less density on the film than D76, but I don't see how that changed the film's speed. All it means is that you need to expose 1 stop more if you are using Perceptol. It doesn't mean the film speed magically changed. A film's speed is a property of its manufacture.

If you need one stop more exposure to get the same density that's a speed change.

The choice of developer for the ASA/BS part of the ISO test was an agreed onenot D76/ID-II but one that actually gave slightly better film speed, the German DIN test was quite different, the ISO speed could be measured by one or the other. But if a different developer had been chosen in either then the speed would possibly have been different. But the films haven't changed.

That's why personal testing is the best option.

Ian

 

[MattKing]

I think what BetterSense is saying is that it isn't the film's "speed" that is changing, it is the "speed" of your procedure and process when using that film.

The film is the constant - the rest changes with circumstances.

It would probably be best for me (as an example) to talk about "Plus-X in exposed moderate contrast light developed in HC110 dil "E" with rotary development after a 3 minute pre-soak and printed using a diffusion light source" speed.

But I am wordy enough as it is .

 

[markbarendt]

I think what BetterSense is saying is that it isn't the film's "speed" that is changing, it is the "speed" of your procedure and process when using that film.

The film is the constant - the rest changes with circumstances.

It would probably be best for me (as an example) to talk about "Plus-X in exposed moderate contrast light developed in HC110 dil "E" with rotary development after a 3 minute pre-soak and printed using a diffusion light source" speed.

But I am wordy enough as it is .

B&W film speed is based on developed density, changing the process (chems, agitation, temp,...) changes the density. That means the speed is directly related to development.

If you want ISO standard speeds use the ISO standard process, if you are not going to use the ISO standard process you may need to test, even informally.

 

[RalphLambrecht]

That's technically correct, Ralph, but since this is all very subjective, "better" may not be applicable. Giving more exposure and increasing development decreases the range of tones but that doesn't make them any less usable. Different, yes, but certainly not less usable. Again, taking Ralph Gibson as an example, one would have to say that his work is not about "better tonality" but HIS approach worked successfully nonetheless. There something to be said about a bold image that falls outside the norm to be interesting versus one that is 100% "correct" but falls flat on its face.

Best,

Max

I was just offering a suggestion what Ian could have meant with 'better' tonality, and I think his statement was OK.

 

[RalphLambrecht]

I think what BetterSense is saying is that it isn't the film's "speed" that is changing, it is the "speed" of your procedure and process when using that film.

The film is the constant - the rest changes with circumstances. ...

I also think that is what BetterSense means, but I have to agree with Mark. There is nothing constant about film speed unless you fix the process parameters. But then it is also correct to say that film speed changes with process parameters.

It's all relative!

I'm comfortable with the idea of changing film speed with processing. That's far easier for me than thinking of my process having a 'speed'. There is nothing wrong with the concept of having a fixed ISO speed and a relative EI which changes with process and/or equipment.