Box ISO rate and Real ISO

Ian Grant · Apr 30, 2014

cliveh said:
Shoot at box speed and develop to your own requirements.

That's not Kodak's recommendations when I used Tmax100. Their large data sheet said to use at 50EI for the best tonality and that matched my own Zone system tests and also John Sexton's excellent articles about the films in Darkroom Techniques.

Ian

removed account4 · Apr 30, 2014

there are a lot of variables in chemical based photography.
folks who practice photography need to create a system/standard
that works for them, and that they have no trouble modifying to suit their needs.

Thomas Bertilsson · Apr 30, 2014

In my opinion the only thing of importance is to develop a system that works for us as individuals. There are so many variables in how we photograph, stretching from camera and shutter tolerances (especially as they age), material choices, technique with metering and the light meter itself, not to mention how we print and final output requirements.

My Gossen Luna Pro does very well at box speed for me. My in camera meter on the Canon EOS 3 likes a lower than box speed EI for the most part (about 2/3 stop), the Pentax KX requires me to set the film speed at half box speed, etc.

The trick to becoming a good craftsman (craftsperson?) is to know our materials well enough to know what to do in all kinds of situations. Nothing else really matters, regardless of what the box says.

Jaf-Photo · Apr 30, 2014

Well, perhaps you can view box speed as a kind of starting point?

Then different films behave differently. Some like both being pushed and pulled, some like one but not the other and some likes neither.

Colour films are different from B&W too, usually requiring you to stay pretty close to box speed.

markbarendt · Apr 30, 2014

Jaf-Photo said:
Well, perhaps you can view box speed as a kind of starting point?

Then different films behave differently. Some like both being pushed and pulled, some like one but not the other and some likes neither.

Colour films are different from B&W too, usually requiring you to stay pretty close to box speed.

You are correct that box is a place to start.

The films and developers are not the wildcards, we are, all us nuts behind the cameras and agitating our films.

The materials we use are remarkably reliable and consistent as long as we do our part.

Our vision for the end result and our preferences in how we like to do things are what drives us to deviate from "normal". These decisions are regularly poorly informed and done for irrational reasons.

As to color forcing us to stay close to box speed, that is at best an urban legend. Kodak's old Portra brochures claimed consistent color from one stop under to two stops over. Disposable cameras are more proof of that.

Ko.Fe. · Apr 30, 2014

I went through the bulk of Fomapan 400 recently. Most of it in Rodinal.
Have hard time to believe it needs twice time for stand developing and twice time for fixing. But true.
Best results were at ISO 200 for me.
Same with Kentmere 400.

Gerald C Koch · Apr 30, 2014

Back when film speed was determined by the ASA (American Standards Association) a specific developer was specified. The formula for which was part of the ASA standard as it was not a commercial developer. Now with ISO standard the manufacturer is allowed to pick the developer that they wish to use. Different manufacturers can use different developers. I personally have never found this idea to be particularly attractive. As the old saying goes "The nice thing about standards is that there are so many of them."

Certain developers like D-76 and Rodinal (with other analogs like R09) do not produce full rated speed. So its is not surprising that Fomapan 400 only yields an EI of 250 in Rodinal. Manufacturers design their films and developers together. My advice would then be to look into one of Foma's recommended developers like Hydrofen. I published the formula and developing times on APUG some time ago.

Xmas · Apr 30, 2014

Ko.Fe. said:
I went through the bulk of Fomapan 400 recently. Most of it in Rodinal.
Have hard time to believe it needs twice time for stand developing and twice time for fixing. But true.
Best results were at ISO 200 for me.
Same with Kentmere 400.

Well the formapan data sheet says 250 ISO in DK76.
So you are not far away,

In 1+100 60 mins at 30C Rodinal &
In Microphen 9 mins at 20C I use 320

I use a Weston incident or zone1 reflective and 200 might be better, I hate empty shadows and open up a stop for non Caucasians.

It fixes quite quickly for me unlike the tabulars which take aeons.

Photo Engineer · Apr 30, 2014

This comment is appropriate here then!

Traditionally, EK ran a release process for all B&W films to verify the speed and curve shape of all films before going out into the trade. The developer used was D-76. They may have changed, but when I was "there" that is what was used. And, the speed ratings were given for an approximate contrast of 0.6 as I have noted before.

Thus, if a Kodak film is developed to a contrast of about 0.6 - 0.8 (professional to consumer range) the speed should be spot on for the box rated ISO speed.

PE

marciofs · Apr 30, 2014

This is all interesting. I don't have much to say but I am follwing.

I use Kentmere 400 to actually push up to 1600 and 3200. And I am experimenting now with Fomapan 400 for the same.
I used to get "strong blacks" (poor shadow definition) with Kentmere and I took a while until realised that it wasn't actually the only characteristic of the negative but only on of the possible results that I was getting, then experimenting other results by reducing development time. But it becomes clear to me that there are a lot more than just development time after using Fomapan and reading about it. Specially after notice that most results I got from negatives are often not exactly the same on the examples I find in the internet. (I like whay I get the best by the way ).

Gerald C Koch · Apr 30, 2014

Michael R 1974 said:
I hate to be a stickler, but how do you know know D-76 does not produce "full rated speed"?

The ASA standard developer was more active than D-76 using sodium carbonate as the alkali. High solvent metol based developers appear to produce slightly less film speed. Once diluted 1+1 the film speed improves. At least this was the conventional view when photo mags were popular. I remember Tri-X being rated at 320 with D-76.

Ian Grant · Apr 30, 2014

Gerald C Koch said:
High solvent metol based developers appear to produce slightly less film speed. Once diluted 1+1 the film speed improves. At least this was the conventional view when photo mags were popular. I remember Tri-X being rated at 320 with D-76.

I agree with you and Michae, back in the 70's when I used ID-11/D76 it was the norm with professionals to shoot FP4/HP5/Tri-X etc at a a third of a stop lower (sometimes a half) than the box speed because this gave better shadow details. Later I switched to Adox Borax MQ which is closely related to the ASA developer and that gave box speed as well as finer grain and better tonality (longer scale) because it was cleaner working (lower base fog).

When I needed to push process HP5 (which I used for photographing rock concerts) I used ID-68 (Microphen) only stopping when Ilford released XP1 then later XP2 which I push processed in C41 chemistry.

It's interesting that Kodak had the old ASA part of the ISO changed because Tmax films couldn't reach the claimed ISO using the previous testing standard. Ilford use a practical set of tests to determine ISO ad developing times.

EFKE are now defunct but their ISO speeds were based on their films performance in Tungsten light and that goes back to the previous manufacturers if the films Dupont and prior to Dr C. Schleussner Fotowerke GmbH. So EFKE KB/R/PL 25 (new ASA name), 14 (old DIN name) is the Tungsten speed.

The speeds went up slightly when the boxes & packaging were changed to reflect their speed in ID-11/DS76 rather than FR 5 which is similar to D23.

It was once common for manufacturers to publish 2 ASA speeds, Daylight and Tungsten although the higher one was used on the box and cassette/backing paper. With slightly less Red sensitivity there's a bigger difference between the Tungsten speed & Daylight speeds with the old EFKE films.

Ilford give 2 ISO speeds for Ortho Plus Daylight & Tungsten, they also state in their datasheets for other films that the ISO's are for Daylight, there won't be a full stop drop and there's so many variables you need to learn by experience or testing how much extra exposure is needed (if any).

Ian

Sirius Glass · Apr 30, 2014

Michael R 1974 said:
Interesting how almost "anti-box speed" people are. Even granting people are disinterested in the basis for ISO speeds (since it seems people tend to view it as some laboratory thing of little practical use in the making of real art, or as a marketing trick), I wonder how many of them are getting what they think they are getting when it comes to the various methods of establishing a personal EI.

Photo Engineer · Apr 30, 2014

Well, there are 2 points here to address.

I usually shoot all negative films about 1/3 stop slower than box speed so as to get better overall latitude. So, a 400 speed to me is a 320.

And, when you push for speed, you are not reallly getting more speed, you are getting higher contrast and less latitude, but the mid scale and lower scale densities are higher thus giving a denser negative at higher speed setting. This is both good and bad. Good, in the sense that you can expose a 400 speed film at 800 or 1600 and get a good image, but bad in the sens that you lose latitude doing so.

Now, thinking about it, I wonder of the release tests were done with D76 1:1. I never really thought about that one as most all workers used it straight.

PE

Stephen Benskin · Apr 30, 2014

Michael R 1974 said:
Interesting how almost "anti-box speed" people are. Even granting people are disinterested in the basis for ISO speeds (since it seems people tend to view it as some laboratory thing of little practical use in the making of real art, or as a marketing trick), I wonder how many of them are getting what they think they are getting when it comes to the various methods of establishing a personal EI.

Michael, exactly my thinking. One of the problems with these types of threads is that there are at least 2 topics being discussed. One is about film speed (especially a speed standard) and the other is about a personal EI.

The ISO film speed standard is a fixed density method that under specific contrast conditions will yield speeds based on the fractional gradient point. This methodology is called the Delta-X Criterion. The fractional gradient point is the minimal point of exposure where the film produces the minimum gradient sufficient for producing an excellent print (it's not 0.10 over Fb+f). It is the film gradient and not film density which is determinant of print quality. By knowing where the factional gradient point lies, exposure or a personal EI can be determined base on what's important to the individual.

For those who point to the difference in the ISO gradient and the gradient for the statistically average normal, film speed changes little with developmental changes when it is based on gradient like with Delta-X and the fractional gradient method. In fact, according to C.N. Nelson in Safety Factors in Camera Exposure, in comparison to the Delta-X Criterion speeds "the fixed-density criterion tends to underrate films that are developed to a lower average gradient and to overrate films that are developed to a higher average gradient."

So as Michael points out, not only are people not getting what they think they are getting, but for those who think the "box speeds" are wrong only think so because they are themselves using methods that are producing inaccurate results.

Ian Grant · May 1, 2014

Stephen Benskin said:
So as Michael points out, not only are people not getting what they think they are getting, but for those who think the "box speeds" are wrong only think so because they are themselves using methods that are producing inaccurate results.

Box speeds are actually just a starting point, after all Kodak actually recommended using Tmax 100 at 50 EI for greater tonality. What's more important is what EI gives you the results you require and that may not be the box speed.

Ian

Doremus Scudder · May 1, 2014

Ian Grant said:
Other way round you mean increase the exposure by decreasing the Effective film speed (EI - exposure index) - to give better shadow detail.

Ian

Thanks for the correction Ian! I got stuck between "increasing exposure" and "decreasing EI" and just made matters more confusing! Hopefully the OP figures it out.

FWIW, it seems pretty well-established that reducing developing times significantly from standard (whatever that is now, since every manufacturer can decide for itself), for whatever reason (contrast control, personal EI, etc.) will reduce effective film speed. With that in mind, it only makes sense, sensitometrically, that if one develops to a lower contrast index, one's personal E.I. will be lower than ISO speed. Mine are, but just a bit: I shoot 320 Tri-X and TMY at E.I. 250. I'm sure my metering techniques and light meter come into play here as well, but that's the point, isn't it? My personal E.I. should give me negatives that have the shadow detail I want and print like I want. I don't really think that I am using methods that produce inaccurate results by doing so.

For color film, even with "standardized" development, there is still the question of metering and meters in general. Not only do individual metering practices vary, so do the light meters themselves, due to design or manufacturing tolerances. I know I have a hard time finding two meters that agree completely. That in itself should prompt everyone using a meter to find their own personal E.I. This is not denying ISO speed, simply compensating.

If I am going to err when shooting black-and-white negatives, then it will be on the side of overexposure. I'm not really interested in "living on the edge" of not getting enough exposure. LF black-and-white film does fine with more than minimum exposure (sometimes better in the case of 320Tri-X).

In any case, the negative is just an intermediate step to get a good print. I'm pretty sure the viewers of my work don't go around saying, "Oh my, he must have shot that at different than box speed!" If box speed is giving you the shadow detail you desire with the way you work, fine. If not, change your personal E.I. to compensate.

Best,

Doremus

markbarendt · May 1, 2014

Doremus Scudder said:
I'm sure my metering techniques and light meter come into play here as well, but that's the point, isn't it? My personal E.I. should give me negatives that have the shadow detail I want and print like I want. I don't really think that I am using methods that produce inaccurate results by doing so.

Fully agree.

The problem that pops up though here on the forums, and in real life ,is when "I" suggest my EI as a remedy to "my buddy's" problem, these suggestions become the root of myths and legends.

The ISO standard gives us a way to "talk the same language". From there we can figure out how our processes differ.

Doremus Scudder said:
For color film, even with "standardized" development, there is still the question of metering and meters in general. Not only do individual metering practices vary, so do the light meters themselves, due to design or manufacturing tolerances. I know I have a hard time finding two meters that agree completely. That in itself should prompt everyone using a meter to find their own personal E.I. This is not denying ISO speed, simply compensating.

I do have two Sekonic L-358's that match.

When I decided to use incident metering as my standard I interestingly found that my judgement about which tone went where when using reflective metering was more skewed than my reflective meters.

Regardless of the meter in question though, testing is important. We need to know how our scene metering relates to the print.

Doremus Scudder said:
If box speed is giving you the shadow detail you desire with the way you work, fine. If not, change your personal E.I. to compensate.

Yep.

markbarendt · May 1, 2014

Ian Grant said:
Box speeds are actually just a starting point, after all Kodak actually recommended using Tmax 100 at 50 EI for greater tonality. What's more important is what EI gives you the results you require and that may not be the box speed.

Ian

Similarly Ilford suggests extra exposure for XP2 to reduce grain.

Stephen Benskin · May 1, 2014

Ian Grant said:
Box speeds are actually just a starting point, after all Kodak actually recommended using Tmax 100 at 50 EI for greater tonality. What's more important is what EI gives you the results you require and that may not be the box speed.

Are a starting point for exposure not film speed. I believe I made this point in my post. The ISO speed gives you information from which to make a personal EI choice.

Doremus Scudder

FWIW, it seems pretty well-established that reducing developing times significantly from standard (whatever that is now, since every manufacturer can decide for itself), for whatever reason (contrast control, personal EI, etc.) will reduce effective film speed. With that in mind, it only makes sense, sensitometrically, that if one develops to a lower contrast index, one's personal E.I. will be lower than ISO speed.

It's a very common misunderstanding. Film speed isn't determined by density because negative density by it self isn't relative to print quality. Film speed is determined by gradient. The fixed density of the ISO standard is a short cut to determining the fractional gradient point. As per Nelson, the fixed density method is only accurate when the contrast falls within the ISO contrast parameters. Otherwise you need to plug ΔD and Δlog-H into the Delta-X equation because with increased and decreased negative development, the fixed density method is less accurate. You're probably conflating it with how an increase in film density usually is accompanied by a higher gradient. This isn't always the case and definitely not to the same degree in different film types. This is all explained in Simple Methods of Determining the Fractional Gradient Speeds of Photographic Materials by C.N. Nelson and J.L. Simonds. If the OP really wants to understand what the REAL ISO is about, this is the paper.

As for a personal EI, whatever makes you happy.

The statement that very manufacturer deciding for themselves what the contrast for the standard should be is patiently wrong. The contrast parameters are clearly defined in the standard. Any variation and the ISO prefix cannot be used.

markbarendt · May 1, 2014

Agreed Michael,

It was interesting for me when I started to grasp the concept of latitude and that we didn't actually ever print everything available from a given film/frame and that our prints generally only represented a fraction of what a given negative held.

When I came back to film I started with slides and was coming from digital where I loved shooting jpeg. It was really tough coming to grips with the thought that what I did with the camera/film only had a general relationship to the print, not an absolute one. That the print I just made was just one possible interpretation of many.

With this realization I started testing the latitude and was amazed just how far one can stray (in EI terms) and still make nice prints, just as expected. Finding the limits of that range, for any given film/developer combo, allows for a great amount of creative freedom and spontaneity without worrying about whether or not I got something workable. It also moved me away from thinking my camera work had screwed my print, at least in most cases.

Photo Engineer · May 1, 2014

Michael, the same arguments hold for both B&W and color as they are generally made to the same overall aim curve shape. The big difference is that color begins to "go off" due to crossover and other effects if you go too far over or under.

PE

mklw1954 · May 1, 2014

Assuming your metering is accurate, make sure you're not using different ISO because you are not developing the film properly. Temperature control in the developer step is important - the solutions may be at the right temperature but if the tank/reels/film are different you won't be developing at the right temperature. Also, your thermometer should be calibrated to a color thermometer to get the right temperature.

Since employing good temperature control (bringing the tank/reels/film to temperature and maintaing it in a water bath, and using a thermometer calibrated to a color thermometer), results shooting at box speed and developing according to instructions have been excellent.

paul ron · May 1, 2014

I run my own speed tests to standardize my exposure technique n printing technique, paper/dev film/del combos, to give me the range of tones that fit my style. I never pay sny attension to box speeds or if my meter jives with another! Its my own standards to fit my equipment n methods.

markbarendt · May 1, 2014

paul ron said:
I run my own speed tests to standardize my exposure technique n printing technique, paper/dev film/del combos, to give me the range of tones that fit my style. I never pay sny attension to box speeds or if my meter jives with another! Its my own standards to fit my equipment n methods.

In the beginning, did you start somewhere close to box?

Box ISO rate and Real ISO

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