Who says “Use half box speed for ZS”?

[Vaughn]

They said it...

And I do not think many take it as a universal truth -- just a handy starting place.

 

[wiltw]

LOL... just another stereotype that is either blindly believed or true enough times that folks consider it universally true.

That is what I conclude based upon Ralph's response in post 83!

 

[Stephen Benskin]

LOL... just another stereotype that is either blindly believed or true enough times that folks consider it universally true.

Take for instance the misunderstanding of the fractional gradient method and First Excellent Print test in this very thread. A group of individuals discussing what they know or have heard but most not having access to the source material. It's not hard to believe how some of these misconceptions could become ingrained.. Humans are built to find patterns and connections. Real or imagined. Fortunately this is a niche topic and not as widely disseminated as the Zone System.

Two potential myths that could come from this thread.

Fractional gradient speeds are at the minimal possible exposure.

The pre-1960 ASA speed was not the same as the fractional gradient speed point. It was actually two stops above it and about one stop above todays. Fractional gradient defines the limiting point of exposure and it is consistent in its results across film types so it's possible to compare speed apple to apples. Interesting disconnect. How can the film speed double with the 1960 standards when the myth is the speed was at the minimum useable gradient?

It's not good to adhere to the results of a dogmatic methodology like the fractional gradient method.

The EI for film speeds was set at two stops above the fractional gradient point. As the fractional gradient point is the limiting gradient for exposure to produce an excellent print and the EI is two stops above it, doesn't that mean, at the very least, that placing the shadow anywhere inbetween the two points is fine. That doesn't sound all that dictatorial.


Back to the OP subject. Obviously the topic wouldn't have occurred before the 1960 standard. It had to happen after, but when. A new edition of The Negative was released in the mid-seventies. I believe this is when the Zone System began to reach a larger audience and probably when the true speed conspiracy theories began to take off.

 

[Stephen Benskin]

A list of obsolete Speed methods. So, if you used one of these, what would your "true film speed" be? The different methodologies between Zone System testing and the ISO standard accounts for most of the 1/2 to 1 stop reported discrepancies in film speed. FYI, only the fractional gradient speed related methods used a psychophysical approach.

 

[Bill Burk]

It is the result of empirical testing of a large photographic community and quite reasonable advise in MHO

Thanks Ralph,

I thought that might have been the answer all along.

So maybe there isn’t any named person who started saying it. Maybe not even a particular day when they started saying it.

Maybe I can get away with this: A large community of photography cannot agree on anything except “use half box speed”. To satisfy their intense desire to disagree... those who give this advice, fiercely disagree about why.

 

[Stephen Benskin]

and color theory too!

Do you know what the sample size is, approximately, in these studies. I understand the Power Test and confidence intervals but never saw the original studies to see the actual subject pool constituency. If that’s in the first two pages previously posted, please forgive me as o can’t read them on my phone. Must wait for a bigger display... thanks to presbyopia and cataracts not ready for fixing yet.

Jones used two groups of 100 judges. He notes, "there is very little difference between the average based upon thirty observers and that including the entire one hundred." It should also be noted that judging for the first excellent print wasn't the only criteria. The judges were asked to judge for "just acceptable."

If you're interested the tests are primarily in a series of three papers.

Jones, LA, The Evaluation of Negative Film Speed in Terms of Print Quality, Journal of the Franklin Institute, Vol 227, March 1939.
Jones, LA, The Evaluation of Negative Film Speeds in Terms of Print Quality (conclusion), Journal of the Franklin Institute, Vol 228, April 1939.
Jones, LA, Nelson, CN, A Study of Various Sensitometric Criteria of Negative Film Speeds, Journal of the Optical Society of America, Vol 30, March 1940.

Kind of like the MCU movies. You had to wait a year for the conclusion.

Stephen

 

[Stephen Benskin]

I’m a long-time fanboy... since graduate school some 40+ years ago, but don’t have an autographed picture. You are very lucky, in a nerdy sort of way!

Not signed. Sadly, Jones died about a month after retiring.

 

[BrianShaw]

 

[Craig75]

Thanks Ralph,

I thought that might have been the answer all along.

So maybe there isn’t any named person who started saying it. Maybe not even a particular day when they started saying it.

Maybe I can get away with this: A large community of photography cannot agree on anything except “use half box speed”. To satisfy their intense desire to disagree... those who give this advice, fiercely disagree about why.

if you look back through the thread though @Renato Tonelli is saying his tests, which he had checked by a 2nd party, showed more than box speed but those kind of results always seemed to get brushed under the carpet.

 

[Stephen Benskin]

if you look back through the thread though @Renato Tonelli is saying his tests, which he had checked by a 2nd party, showed more than box speed but those kind of results always seemed to get brushed under the carpet.

Apart from the obvious answer that there are always variations from the norm, we have no idea how the test was performed. Was it repeated with the same results? Just because I gave someone my data and they checked it, doesn't confirm that the testing methodology was appropriate and without errors. Even if the testing was good, it can just be an outlier. We need more information to properly evaluate the claims.

Once again, most of the Zone System testing resulting in speeds 2/3 slower than the ISO rating is because the testing procedures are different. In effect, one stops down 4 stops and one stops down 3 1/3. The vast majority of Zone System users got results of 1/2 - 1 stop under box speed not because that was the actual speed, but because they all used a similar methodology. In reference to this thread, you'd expect a population using a similar methodology to obtain similar results. It doesn't make the results or conspiracy theories any more valid - ad populum. The results should stand or fall on their own merit.

Two outside temperature readings at the same time. One in the sun and one in the shade. They can't be expected to be the same. You need to know the methodology to properly understand the data. Renato only said he made a test. Nothing about how the test was made.

In the medieval ages people thought a mandrake root looked like a human. They concluded that when picked, it would scream and anyone around would go mad. So, they put beeswax in their ears, tied the root to a dog and whipped the dog. The root got picked. Just because people agree with something and the methodology produces results, doesn't make it correct.

 

[Craig75]

Apart from the obvious answer there are always variations from the norm, we have no idea how the test was performed. Was it repeated with the same results? Just because I gave someone my data and they checked it, doesn't confirm that the testing methodology was appropriate and without errors. Even if the testing was good, it can just be an outlier. We need more information to properly evaluate the claims.

Once again, most of the Zone System testing resulting in speeds 2/3 slower than the ISO rating is because the testing procedures are different. In effect, one stops down 4 stops and one stops down 3 1/3. The vast majority of Zone System users got results of 1/2 - 1 stop under box speed not because that was the actual speed, but because they all used a similar methodology.

Two outside temperature readings at the same time. One in the sun and one in the shade. They can't be expected to be the same. You need to know the methodology to properly understand the data. Renato only said he made a test. Nothing about how the test was made.

In the medieval ages people thought a mandrake root looked like a human. They concluded that when picked, it would scream and anyone around would go mad. So, they put beeswax in their ears, tied the root to a dog and whipped the dog. The root got picked. Just because people agree with something and the methodology has results, doesn't make it correct.

View attachment 274412

I agree but (am my understanding is very basic and likely incorrect) - emulsion speed is determined by an average of different samples and some variance is allowed ie the master roll isnt a consistent 100 iso (or whatever) across every part of it. Just that alone will affect individual results and I am sure people can think of a number of uncontrollable factors for the end user in testing.

 

[Stephen Benskin]

I agree but (am my understanding is very basic and likely incorrect) - emulsion speed is determined by an average of different samples and some variance is allowed ie the master roll isnt a consistent 100 iso (or whatever) across every part of it. Just that alone will affect individual results and I am sure people can think of a number of uncontrollable factors for the end user in testing.

True, ISO speeds are an averaging of a large number of samples from a number of batches produced over a period of time. Manufacturing tolerances and testing controls tend to limit the range of variance to something like 1/6 of a stop if I remember correctly. Good testing is also designed to eliminate as many variables as possible and repeating tests can catch any instance a mistake was made doing any one test. Zone System testing doesn't address many variables and accepts many more that don't have to do with emulsion speed. That's why unsupported claims have to be taken with a grain of salt.

 

[foc]

Two outside temperature readings at the same time. One in the sun and one in the shade.

Of course you know that the correct way to measure air temperature is in the shade?
But yes I get your point.
I also like your mandrake root analogy.

 

[Stephen Benskin]

Of course you know that the correct way to measure air temperature is in the shade?
But yes I get your point.
I also like your mandrake root analogy.

I do. I've always like the mandrake analogy too. Never sure if it's really appropriate.

How about one about measuring when water boils. Not a Celsius thing, but one measured at sea level and the other at a higher altitude. Without that information, we have conflicting results even though there is no right or wrong.. The context / conditions of a test need to accompany test results. Else you can get 50 years of conspiracy theories.

 

[Doremus Scudder]

Just throwing this out for consideration:

Empirical testing by a largish group of people, aka common knowledge, can be mistaken, but can also reflect real trends and phenomena. I think that holds true more for modern times, where the "scientific method" of hypothesis-testing-evaluting results is widely accepted and used compared to, say medieval times, when "reasoned-out" information without the benefit of comparison with the real world was more in vogue (e.g., the mandrake analogy).

I have a tendency to think that the experience of lots of photographers, who are interested in getting as much speed out of their film as possible while at the same time being able to make excellent prints from their negatives, would have a tendency to push to the limits of the system in order to optimize these two variables. Many of these same photographers are skilled lab workers with willingness and ability to do lots of non-technical testing.

Assuming that to be true along with the general consensus (rather general, I presume) that rating the film somewhat slower than box speed gives better results, shouldn't we at least entertain the notion that, yes, it is indeed likely that rating the film slower than box speed does indeed give better results?

In other words, why would the practice of rating the film slower than box speed be so prevalent if it didn't have an advantage, especially when it comes at a cost, i.e., needing to use slower shutter speed and/or larger apertures, which is rarely convenient in LF work?

In my personal experience, I couldn't make a print that I liked until I started rating my film a bit slower than box speed (1/2-2/3 stop for me, e.g., 320 Tri-X @ E.I. 250 and TMY @ E.I. 250 as well). Only when I started giving that little bit more exposure could I get the richness in my prints that I desired.

Where is the opposite view: that rating the film faster than box speed gives better results? Yes, there is a school of "pushers" out there, but they accept the loss of shadow detail and/or like the "look," which is likely not in the parameters of the instructions to the judges of the "first excellent print" test.

Just questioning...

Doremus

 

[Huss]

I don't trust the box speeds on Lomo Fantome 8 and Babylon 13. I rate Fantome 8 at 6, and Babylon 13 at 12.
Night and day difference.

 

[wiltw]

Just questioning...

Doremus

Just musing to your questioning...

Perhaps the issue back before 1960 was no true consistency between brands in rating film speed, and in 1960 by defining 'the minimum' point along the sensitometric curve that helped to establish more CONSISTENCY of rating. That might be the only 'benefit' of the 1960 action, and better exposures resulted by using the 'a bit more exposure than box rating' Certainly color neg improves with +1EV to reduce muddy shadows.

 

[MattKing]

Where is the opposite view: that rating the film faster than box speed gives better results?

If you have a lab do all your work, and you are just getting machine prints - not custom enlargements - using box speed will probably give you more good results.
Box speed tends to give good mid-tone and highlight rendition in straight prints.

 

[Doremus Scudder]

If you have a lab do all your work, and you are just getting machine prints - not custom enlargements - using box speed will probably give you more good results.
Box speed tends to give good mid-tone and highlight rendition in straight prints.

Aha!

Maybe fine-art and custom printers of B&W prints have a markedly different set of standards than the processing machines do, and different criteria for what makes an "excellent" print?

Or (conspiracy-theory alert), maybe "box speed" was adopted as a standard simply because it gave the best "straight prints" from processing machines?

Doremus

 

[MattKing]

Aha!

Maybe fine-art and custom printers of B&W prints have a markedly different set of standards than the processing machines do, and different criteria for what makes an "excellent" print?

Or (conspiracy-theory alert), maybe "box speed" was adopted as a standard simply because it gave the best "straight prints" from processing machines?

Doremus

It isn't so much different criteria for an excellent print, but rather different criteria for a negative, because custom printers don't restrict themselves to negatives that print without any darkroom manipulations.
Fine art and custom printers also tend to pay more attention to shadows than most of the population - I expect it is an earlier version of "pixel peeping".
If you want people to like your photos, than you will have lots more success if the mid-tones and highlights look good.

 

[Adrian Bacon]

I always assume that the manufacturer rounds up by a third of a stop, and assume that the shutter/aperture will only be within half a stop, and my developer choice probably isn't the most speed producing. Knowing that the worst thing you can do is under expose film, based on that, I generally bias towards over exposure, and half box speed is a nice starting point for a film that is new to me. Once I've run a bit of it, I adjust to my liking.

 

[Craig75]

I would agree with Michael_r that there seems to be a lot of suspect written material in photo technique books by photographers (as opposed to scientistic papers) that does mean a lot of us (def including me) have ended up with a load of nonsense in our heads as facts.

 

[Ian Grant]

I literally do not remember who said it first or who says it now.

I have repeated it so many times that searches on Photrio are going to keep pulling up my posts.

Who is it that started telling new Zone System users to “just use half box speed”, since that’s what your tests are going to find anyway.

I don’t want to keep saying “they always say” if I can credit some or a few people.

Well that's blanket statement.

With some film developer combinations that is in my experience the case, older Tmax 100 & 400 in Xtol and?pyrocat Hd but Ilford films don't need the same drop, Agfa (not rebranded) none.

For many years I sot Tmax 100 at 50EI, EfFKE Pl 25 at 50EI (it's daylight box speed, and Agfa AP/APX100 box speed same dev tank and times. There's no rule of thumb except between makes.

Ian

 

[Doremus Scudder]

Can’t agree with any of this I’m afraid, including the underlying assumptions. Basically I would say the prevalent practice of rating films at lower than ISO speed is based on a combination of nothing, and tradition (also based mostly on nothing, along with the desire to emulate the working methods of some good photographers who also didn’t really know why they were doing what they were doing, and were using totally different materials). It has nothing to do with better results. In my experience, a very, very small number of photographers make good prints, or are even interested in print quality. This is not surprising. All art forms are like this.

Interesting...

I'm still curious then as to why anyone would go to the trouble of rating their film differently from the manufacturer's suggestion if it really makes no difference in the final results.

I'm still not convinced that photographers of the skill levels on this forum (and over on the LF forum) would just blindly follow advice about film speed that introduces a greater level of difficulty in image making (working with slower film is harder than working with faster) just because AA or Barnbaum or whatever other master photographer recommended it.

Which also begs the question: Why did the practice come into being in the first place? If there were never any advantage to downrating your film speed, why would anyone even bother? Maybe the whole thing is just a safety factor that was once useful (because of the unreliability of older meters, etc.) that is no longer necessary?

Certainly, underexposing has disadvantages whereas slight overexposure does not, especially with larger film sizes.

If that's all it is, well then, I'd probably stick with my 1/3 - 2/3 stop adjustments in E.I. just to be on the safe side. A whole stop though might convince me to do some "testing."

Still, I have a hard time thinking that numerous intelligent practitioners of photography, whose goal was to make excellent final prints, would consistently arrive at the same practice without some basis in reality.

Best,

Doremus

 

[Stephen Benskin]

Just musing to your questioning...

Perhaps the issue back before 1960 was no true consistency between brands in rating film speed, and in 1960 by defining 'the minimum' point along the sensitometric curve that helped to establish more CONSISTENCY of rating. That might be the only 'benefit' of the 1960 action, and better exposures resulted by using the 'a bit more exposure than box rating' Certainly color neg improves with +1EV to reduce muddy shadows.

Today's b&w ISO speed rating still establishes the fractional gradient speed point, but it does it mathematically. The ISO developmental parameters that need to be met before determining film speed is the Delta-X Criterion method. When Delta D from the standard is 0.80, the fractional gradient speed point falls 0.297 log-H to the left of the fixed density point of 0.10. If you read the two page excerpt from the Safety Factor paper, they give you the reason.