Who says “Use half box speed for ZS”?

Bill Burk

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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.
 

ic-racer

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The Picker books suggest this but maybe not the quote you seek.

"My Tri-X rating is 1/2 the manufacturers rating. I have access to an electronic shutter speed tester and my shutter is close to accurate."
"My experience in checking the tests of workshop students indactes that in a bout 80% of cases, 35mm Tri-X must be rated lower than ASA 400."

Zone IV Workshop, Amphoto, Garden City NY ©1974
 
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wiltw

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Given how ZS first came about around 1940, and the fact that films had an ASA re-rate about 1960, such as ASA 200 film rerated to ASA 400, it is understandable how such a conclusion might arise, to be consistent with the original teachings of the 1940's and 1950's!

Ansel Adams himself sort of side steps around the issue in The Negative, mentioning how film makers may change rating and reminding the user to carefully read the tech sheet and perform PERIODIC TESTING confirming the individual user's own rating for validity. He alludes to the re-rating of films which he had experienced.

On another forum, someone posted in 2007
"I took a B&W Printing Course at SVA in NY. The instructor was very strict with
the following instructions and I would love to hear your Point-Of-View;
whether you agree or disagree.

"EXPOSING THE FILM
"He claims, all B&W film manufacturers fake (?) their ISOs. So (?), you should
always halve the ISO (i.e. shoot at 200 if you buy ISO 400, and then develop
at 20% less time than the manufacturer's recommended time.) "Everyone knows
and does this", he said... Use Zone System to expose the film."​
 
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Vaughn

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I always have heard (here and elsewhere) that:
1) ASA/ISO are determined by tests that are not always closely correlated with real-world usage.
2) Companies will fudge to get a higher rating.
or 3) Pick a conspiracy theory of your choice.

With that and exposure being the limiting factor for shadow information, exposing at the meter reading and then at 1 stop more seems a sensible plan if one is not going to carry out the whole testing regime. Given the latitude for B&W negative film, a beginner should be able to nail a few shots with just a little instruction on metering. I believe I told all our students that when they took out the 4x5s for the first time...along with be aware the RF monster and the bellow extension correction.
 

Nicholas Lindan

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I sez it.

I went through the whole rigmarole back in the 70's and ended up with Tri-X at somewhere around 250-300. I found I am not alone - it seems everyone comes up around a stop short. So why not save an awful lot of film and chemistry and buy the wife something nice with the money you would have thrown away on a densitometer?

In any case a stop of safety margin and a stop's more shadow detail are nice things to have. I don't always meter to a gnat's backside of shadow detail. In my take the ASA/ISO speeds are the highest speed you can rate the film and still bring back Mr. Jones' "First Excellent Print." Going at the highest rated anything is something I have found to be a generally bad idea.

For color transparency it is a whole 'nuther matter.

I think it all started with the Illuminati.
 
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Paul Howell

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I've found that I can shoot Tmax 100 and 400 at box or higher when shooting with a modern (well a more modern film) camera with matrix metering and electronic shutter. With my 4X5, MF, and mechanical shutter 35mms are all over the map. I've never found that I need to shoot film Trix or any other film at 1/2 speed as a general rule.
 

Horatio

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Inaccurate shutter speeds would certainly have an effect, but that would be camera-specific, would it not?
 
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Bill Burk

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michael_r said:
I don’t know who said it first but I say it all the time on here and LFPF. I usually say 2/3 stop just to be correct, and then recommend simply rounding it to a stop..... It’s almost as bad as the “true speed” nonsense.
Click to expand...

I consider “correct” to be a whole stop, not rounding, but correcting additional differences in methods.

I often mention the 2/3 stop obvious difference first. Next most significant difference is ZS N is not 0.62 CI - it’s closer to 0.55 (but still uses 0.1 speed point).

As for the true speed, you can’t argue with any speed used to create a beautiful print. So everyone is always one shot away from finding what works for them.
 

Sirius Glass

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Does anyone see the logical fallacy? If "all B&W film manufacturers [are] fake", then taking the fake data point and divide by two is fallacious.
 

Nicholas Lindan

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Sirius Glass said:
If "all B&W film manufacturers [are] fake"
Click to expand...

I don't think anyone is saying that. The Zone System uses a different method than ASA/ISO for determining film speed - and it invariably results in 2/3 to 1/2 of the box speed. Sounds like a ringing endorsement for the accuracy of the manufacturers' numbers.

A lot of us don't pay much heed to the Zone System for negatives but do find it advantageous to be generous when exposing negative films.

In AA's book The Making of 50 Photographs it is interesting to read that almost none of his iconic images were made using the ZS.
 

Sirius Glass

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Check out the original post that I quoted. Evidently an instructor said it.
 

wiltw

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Sirius Glass said:
Does anyone see the logical fallacy? If "all B&W film manufacturers [are] fake", then taking the fake data point and divide by two is fallacious.
Click to expand...
OTOH, an interpretation that one can draw is
  1. the pre-1960 definition of film speed resulted in what many find to be 'better exposure' than the post-1960 definition of film speed (the mininmum)
  2. so if you divide current box speed / 2, you will result in the 'better exposure' that was obtained yesteryear
Just saying. Not calling anything 'a lie', merely recognizing that the standard was different now vs. back then.

If the very common technique is to overexpose color neg by +1EV in order to get less muddy color in the shadows, then 'divide by 2' might be a better rated speed than what is on the box.
One might argue that while 'divide by two' is good practice for B&W or color neg, while the box speed is better for exposing color transparency in order to not blow out the highlights, so the post-1960 rating is better for that.
Toe-may-toe, Toe-mah-toe
 
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Bill Burk

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Horatio said:
Inaccurate shutter speeds would certainly have an effect, but that would be camera-specific, would it not?
Click to expand...

In the lore I recall, there is a tendency to mention the equipment checks OK.
 

Andrew O'Neill

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I don't think I've said to use half box speed, but I'm pretty sure I've said one should test to see which EI gives you what you want, depending on film used. It can be held box speed, but for most of the film's I use it's two thirds stops less box speed.
 

Maris

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I use an alternative approach particularly in large format work. This is to give MAXIMUM USABLE exposure.

No, not maximum possible exposure but rather that exposure which fills the film with as much information as it can hold without blocking highlights where I want tonal gradation. A negative full of information offers the greatest versatility and expressive possibilities.

In modern times the role of N+. N, and N- development is worth discarding to be replaced by changing paper grades on the superb variable contrast papers now available. A change from paper grade #2 to grade #3 is remarkably equivalent to a N+1 development change, for example.

The possibility of split grade burning and dodging on variable contrast paper can achieve results the classic zone system cannot do.

I'll say the zone system is now effectively obsolete in terms of making the best possible black and white prints.

And in pursuit of maximum usable exposure I often find my light meter is set to half box speed.
 

wiltw

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michael_r said:
The change in the standard was to remove the safety factor, reflecting the improvements in exposure meters etc.
Click to expand...

That was the reason that was officially given. Not to promulgate a conspiracy theory, but maybe the film lobby had the safety factor removed so as to give the impression that films of the era were faster than practically speaking. The pragmatists simply adopted a 'divide box speed by 2' practice, to get them back to the results they used to get before the 1960 standard adoption! And the rest is unrecorded history.
 

Vaughn

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Horatio said:
Inaccurate shutter speeds would certainly have an effect, but that would be camera-specific, would it not?
Click to expand...
A lot of different types of shutters out there. I deal mostly with shutter/lens combo for large format work. They can vary with the amount of exercise they get, how old, etc. generally they slow down a bit as the shutter speeds get longer, or too short. Most folks who CLA these shutters provide a list of the actual shutter speed of each setting. The secret is to always use B or T...

I have counted out exposures of 3 to 5 minutes often enough (keep forgetting to bring a watch or phone), and sometime longer. Generally my count is too long which I figure just helps with resiprocity failure...and being off a few seconds every 60 seconds is not significant.
 

RalphLambrecht

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don't know but it's close to true. I suggest 2/3 top below box speed as start. most film tests verify this.
 
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