Do you test your film for true ISO?

[Bill Burk]

#4 shot at box speed certainly looks the best to me also. My own procedure since I shoot landscapes and develop 120 roll film in an outside lab is to bracket my shots +1 and -1 from box speed regardless of the type of film: color or BW negatives or positive chromes. This allows for lab processing variables as well as my mistakes in calculating exposures. It also allows me to see different contrast ranges and select the final exposure frame I want to use.

#4 looks the best because handle2001 did not try to make the best print he could from each frame. Once you realize that overexposure in a black and white negative process is a situation that can be compensated for by printing down... the possibility that 250 is the best speed can be appreciated.

 

[handle2001]

Ok then if I understand correctly the benefit to this that by shooting at a lower EI (i.e. deliberately over-exposing) I'm pushing the shadow detail up out of the toe where it will have more definition in the final print if that's what I desire. Denser negative and all that. I guess what confuses me then is that people often say, for example, they always shoot Tri-X at an EI of 320 or 250, yet I can think of situations where I would *not* want detail in certain shadows and yet there they'll be, adding density to my negatives. I'm starting to think I wouldn't really see much benefit from shooting under box speed unless I was also able to adjust development to compress the highlights back down into a reasonably printable range, something that's not very practical on roll film. Am I way off base here?

 

[Xmas]

Depends

If you can meter accuratly you can shoot at ISO.

Is you are occasionally a stop out eg 1% of time then

0.5 % will have missing zone 1 shadows
0.5 % will need to print for longer

Depends how accurately you can meter.

You need a contrasty scene for a test shoot five frames, -2, -1, 0, +1, +2 of a stop

Waste a weekend printing all five don't tell us what your answer is...

 

[georg16nik]

Ok then if I understand correctly the benefit to this that by shooting at a lower EI (i.e. deliberately over-exposing) I'm pushing the shadow detail up out of the toe where it will have more definition in the final print if that's what I desire. Denser negative and all that. I guess what confuses me then is that people often say, for example, they always shoot Tri-X at an EI of 320 or 250, yet I can think of situations where I would *not* want detail in certain shadows and yet there they'll be, adding density to my negatives. I'm starting to think I wouldn't really see much benefit from shooting under box speed unless I was also able to adjust development to compress the highlights back down into a reasonably printable range, something that's not very practical on roll film. Am I way off base here?

In the last 50 years, most photographers who print, traditionally down-rate the box speed of the film.
Before the ISO standard was finessed in 1960, what we call now down-rated speed was the box speed.
So, in 1960 the interested parties figured that quoting higher films speed won't hurt sales - the greatest “speed” increase in the history of B&W film.
So, the box speed is just a number.

Hey, it's a free world - everyone's free to bury the shadows even under the toe of the curve.
You will waste more paper that way - more power to you.

 

[removed account4]

Ok then if I understand correctly the benefit to this that by shooting at a lower EI (i.e. deliberately over-exposing) I'm pushing the shadow detail up out of the toe where it will have more definition in the final print if that's what I desire. Denser negative and all that. I guess what confuses me then is that people often say, for example, they always shoot Tri-X at an EI of 320 or 250, yet I can think of situations where I would *not* want detail in certain shadows and yet there they'll be, adding density to my negatives. I'm starting to think I wouldn't really see much benefit from shooting under box speed unless I was also able to adjust development to compress the highlights back down into a reasonably printable range, something that's not very practical on roll film. Am I way off base here?

hi handle2001

from my experience over or under exposing 1 stop and processing "normally" ( as if it was box speed or whatever my "normal" developing time is )
really is not that much of a difference than the iso stated on the box. it is a subtle difference not so much of a difference you can't print the negative.
that's the beauty ( for me at least ) about film, you have 3 speeds to choose from on the same roll and process normally and things usually work out.
it is OK to be exact, its ok to be precise but if it leaves me scratching my head because i can't decide how to expose a roll of film it is a waste of time.
that's one of the reasons i like using low tech cameras when i can ( or just setting my leica, or graflex slr, or pen ft or .... on f"x" and 1/30th S and focusing )
you just load them and use them, and don't worry about iso or fstops &c, it frees me to think about what photography is, that is composition and light and shadow.
obviously everyone likes photography for different reasons, but getting perfect empty exposures is not why i do it ...
while i enjoy reading 9 pages about ISOs and toes shoulders, slopes extended/reduced development &c, its fun to read, but i don't really care about that stuff
i'd rather just expose and develop and print, because in the end, if all an image shows is that the exposure was good, and it scanned and printed easily, but the frame was empty,
to me that's a waste of film that could have had an image on it.

YMMV

btw

the attached scan shows shelf stored extremely expired tri x and tmy exposed at 200 and 800 side by side on the same 4x5 sheet of film.

good luck !
john

 

[Sirius Glass]

Ok then if I understand correctly the benefit to this that by shooting at a lower EI (i.e. deliberately over-exposing) I'm pushing the shadow detail up out of the toe where it will have more definition in the final print if that's what I desire. Denser negative and all that. I guess what confuses me then is that people often say, for example, they always shoot Tri-X at an EI of 320 or 250, yet I can think of situations where I would *not* want detail in certain shadows and yet there they'll be, adding density to my negatives. I'm starting to think I wouldn't really see much benefit from shooting under box speed unless I was also able to adjust development to compress the highlights back down into a reasonably printable range, something that's not very practical on roll film. Am I way off base here?

No you figured out that the film manufactures know their own products better than some hack on the web.

 

[removed account4]

No you figured out that the film manufactures know their own products better than some hack on the web.

it has nothing to do with hacks on the Internet ..
people have been using Asa/ISO and development times as starting points ..
including ansel adams , and I don't think many people would call mr adams a hack ...

 

[ColColt]

For over 35 years if I'm shooting Tri-X or HP-5(or any slower film for that matter) and it's an overcast day or if the entire roll will be shot in flat conditions I shoot it at rated 400 speed. If I'm out and plan on using the entire roll on a bright sunny day with ink like shadows then I shoot at 200-250 and develop accordingly. Seems to have always worked for me.

Others here shoot at 200 all the time with the developer and/or dilution of choice and it works out fine for them. No point in reinventing the wheel.

 

[Stephen Benskin]

In the last 50 years, most photographers who print, traditionally down-rate the box speed of the film.
Before the ISO standard was finessed in 1960, what we call now down-rated speed was the box speed.
So, in 1960 the interested parties figured that quoting higher films speed won't hurt sales - the greatest “speed” increase in the history of B&W film.
So, the box speed is just a number.

Hey, it's a free world - everyone's free to bury the shadows even under the toe of the curve.
You will waste more paper that way - more power to you.

From Safety Factors in Camera Exposure: (Sounds like a conspiracy to me)

"During the past three or four years, much criticism has been aimed at the safety factor involved in the use of American Standard exposure indexes' with exposure meters calibrated in accordance with Ameri¬can Standard procedures. A number of articles in photographic magazines have pointed out the penalties and disadvantages resulting from the use of too large a safety factor and have urged that a smaller safety factor be introduced by means of a revision in the American Standard for determining ASA exposure indexes for black-and-white negative films. The general spirit of these articles is illustrated by the following title of one of them: "ASA Exposure Index: Dangerously Safe."

A safety factor exists in a camera exposure whenever that exposure is greater than the minimum camera exposure that will produce a negative from which a print of excellent quality can be made. The ratio of the actual camera exposure to this minimum camera exposure is, by definition, the safety factor.

If a large safety factor is used, the negatives obtained will, on the average, be much denser than is required for making a high-quality print. A small safety factor means thinner negatives. The main advantages of negatives resulting from the use of a small safety factor are:

1. Easier focusing of enlargers
2. Shorter printing times
3. Less graininess in enlargements
4. Sharper pictures
a. Greater depth of field
b. Reduced subject-motion blur
c. Reduced camera-motion blur

Another advantage, found with the use of some films (especially if they have been overdeveloped), is that the shape of the part of the density-vs-log exposure curve which is used for the thinner negatives is better than the shape of the part of the curve used for the heavily exposed negatives.

Because of these advantages, many photographers are convinced that the best camera exposure is one which is only slightly greater than the minimum camera exposure required for a print of high quality.

The main disadvantage of a small safety factor is that occasionally an underexposed negative will be obtained as a result of an error in camera exposure. The original purpose of the safety factor was to absorb such errors. Present-day experience with color reversal films, for which a large safety factor cannot be used, shows, however, that the number of underexposed pictures resulting from the use of a small safety factor is remarkably small.

If a large safety factor is undesirable at the present time, why was it thought to be necessary when the American Standards for film ratings and exposure meters were first adopted in the 1940's? The first reason is that exposure meters, camera shutters, and lens apertures were not as accurate in the 1940's as they are in 1959. The second reason is that the camera-exposure latitude of black-and-white films was effectively greater in those earlier years, largely because the increase in print graininess with increase, in camera exposure was not as evident with the large cameras, large negatives, and small degree of enlargement or contact printing then commonly used. The great increase in the number of small cameras in recent years and the increase in the degree of enlargement has made the graininess problem more acute.

Many photographers have adopted the practice of giving less exposure than is indicated by the use of ASA exposure indexes with exposure meters. The American Standard indexes for black-and-white films are used by them only as a starting point for deriving a new kind of exposure index which is obtained by the simple procedure of doubling the Standard exposure index. This practice, of course, has the effect of cutting the safety factor in half, giving the preferred thinner negatives.

In recognition of this practice, a new Subcommittee, PH2-18, of the American Standards Association was formed a little more than a year ago for the purpose of revising the American Standard for Determining photographic speed and Exposure Index. Under the chairmanship of J. L. Tupper, .his Subcommittee has prepared a draft of a new Standard which will very likely be officially approved soon by the ASA Sectional Committee PH2 on Photographic Sensitometry (M. G. Anderson, Chairman), the Photographic Standards Board, and the officials of the American Standards Association. In this proposed Standard, the level of the numbers used for rating black-and-white films is approximately doubled. Such a change would have the fleet of reducing the safety factor to one half its present value.

There are no plans for reducing the safety factor by means of a change in the calibration formula or exposure meters because there are too many meters in existence with the present calibration and because the meters are also used for color film for which no change in exposure level or film rating is required or desired."

 

[Sirius Glass]

No you figured out that the film manufactures know their own products better than some hack on the web.

it has nothing to do with hacks on the Internet ..
people have been using Asa/ISO and development times as starting points ..
including ansel adams , and I don't think many people would call mr adams a hack ...

No, I am talking about the computer hacks and testinestas, not the people following the Zone System in some form. I add "in some form" because the Zone System was formulated for sheet film developing duplicate shots separately at N-1, N-2, ... Using the Zone System with roll film can be problematical.

 

[MattKing]

The pre-1960 ASA standard weighted shadow detail more heavily than highlight detail.

The post-1960 ISO standard is strongly based on print evaluation data, which reflects a preference for highlight detail. The prints used in the supporting research were un-manipulated - think of the output from commercial photo labs.

Those of us who print in the darkroom tend to prefer extra detail in the shadows, because of the availability of print manipulation tools and other factors.

The change in the standard reflects changes in materials, and careful evaluation of viewers' preferences.

You may very well prefer the results obtained when you lower your EI, and therefore give your film more exposure.

But I would suggest that you pay close attention to how the highlights display when you print the negative appropriately, before you decide.

 

[Bill Burk]

The post-1960 ISO standard is strongly based on print evaluation data, which reflects a preference for highlight detail. The prints used in the supporting research were un-manipulated - think of the output from commercial photo labs.

MattKing, I think you might be a little mistaken on your thoughts here... I think the print study results were used before 1960, and I got the impression there was a definite preference for a certain minimum amount of shadow detail. I agree with your other points.

But the thing I find interesting - and which influences what I do - is that although the prints were "unmanipulated", I think they were carefully matched in the darkroom to paper contrast and print exposure. I think the studies might have found thin negatives printed on grade 4 were best. I don't know if that information was provided it's just a gut feeling when I read that they made "the best possible prints".

 

[Sirius Glass]

The pre-1960 ASA standard weighted shadow detail more heavily than highlight detail.

The post-1960 ISO standard is strongly based on print evaluation data, which reflects a preference for highlight detail. The prints used in the supporting research were un-manipulated - think of the output from commercial photo labs.

Those of us who print in the darkroom tend to prefer extra detail in the shadows, because of the availability of print manipulation tools and other factors.

The change in the standard reflects changes in materials, and careful evaluation of viewers' preferences.

You may very well prefer the results obtained when you lower your EI, and therefore give your film more exposure.

But I would suggest that you pay close attention to how the highlights display when you print the negative appropriately, before you decide.

So if one wants more shadow detail ala the pre 1960 style then shoot at half the box speed since around 1960 most film speeds doubled. Hence no testing is needed if this is what you want.

 

[Bill Burk]

I still think people should try to evaluate the contrast that they are getting. And I think the "one wasted shot" approach is the least expensive test that one can do... Take a normal shot of something, then take an extra shot two stops overexposed. When developed, you should be able to invent a way to tell if the two shots are one stop apart in terms of density, which would indicate a 50% gradient.

Then accept the rated speed of the manufacturer and recognize that it is likely the true speed of the film. Do what you like (shoot half rated speed). As you see fit.

 

[MattKing]

MattKing, I think you might be a little mistaken on your thoughts here... I think the print study results were used before 1960, and I got the impression there was a definite preference for a certain minimum amount of shadow detail. I agree with your other points.

But the thing I find interesting - and which influences what I do - is that although the prints were "unmanipulated", I think they were carefully matched in the darkroom to paper contrast and print exposure. I think the studies might have found thin negatives printed on grade 4 were best. I don't know if that information was provided it's just a gut feeling when I read that they made "the best possible prints".

Bill:

Your points don't match my understanding, but they may very well be correct.

I really doubt, however, that the standards are based on grade 4 paper. In the 1960s, most (35mm) films were relatively grainy, but 35mm was certainly becoming more main stream.

A thin 35mm negative printed on grade 4 was unlikely to yield "the best possible prints".

 

[Bill Burk]

Bill:

Your points don't match my understanding, but they may very well be correct.

I really doubt, however, that the standards are based on grade 4 paper. In the 1960s, most (35mm) films were relatively grainy, but 35mm was certainly becoming more main stream.

A thin 35mm negative printed on grade 4 was unlikely to yield "the best possible prints".

True, the best possible prints probably really did print on a normal grade. It's that old conspiracy theory mindset run amock...

Mees did show pictures of people judging prints in my copy of "The theory of the photographic process" from 1942... So am sure the excellent prints went into an earlier ASA standard. Exactly which one, is probably easy to find.

 

[Stephen Benskin]

But the thing I find interesting - and which influences what I do - is that although the prints were "unmanipulated", I think they were carefully matched in the darkroom to paper contrast and print exposure. I think the studies might have found thin negatives printed on grade 4 were best. I don't know if that information was provided it's just a gut feeling when I read that they made "the best possible prints".

From The Evaluation of Negative Film Speeds in Terms of Print Quality, "Having obtained a series of test negatives for each of the four negative materials, prints were made therefrom. Those responsible for making these prints were instructed to make the best possible print from each negative by using any one of the six contrast grades of developing out papers. In order to do this, it was of course necessary to make a series of prints, in which the printing exposure was varied on each of two or three of the contrast grades...From each group of such prints, one was chosen as being the best that could be made from that negative with any variation of printing paper contrast and printing exposure. In this way a series of twelve prints was obtained for each of the four negative materials."

 

[RalphLambrecht]

Sometimes...

I have in the past, but not currently. My constraint is not equipment. I have a nice densitometer purchased new by me years ago. My constraint is time and weather. Time due to job responsibilities. And weather because clear sunny skies are my uniform light source of choice for the test exposures, and the Pacific Northwest doesn't have many of those over the course of a year to begin with. Especially on Saturdays and Sundays.

These days I simply use box speeds and recommended development times. Fine tuning will need to wait until retirement in a few years. The procedure is not difficult. And as David says, one can learn a lot by doing it.

I can't even imagine what waking up each morning and doing what I want to do will be like. That hasn't happened on a long-term basis since I was 4-years-old.

Ken

Ido that every day.It's great! Work is extremely overated

 

[RalphLambrecht]

designing a practical and meaningful test procedure is an art and the result will always be questioned by the good, the perfect and the lazy.

 

[removed account4]

designing a practical and meaningful test procedure is an art and the result will always be questioned by the good, the perfect and the lazy.

spoken by a true genius

 

[RalphLambrecht]

How to rate the film is less about it's actual speed and more about personal taste, needs, and metering method. All of which is discovered through use. All of which isn't film speed but EI.

Apart from the Zone System testing, there's the Delta-X Criterion method (modified fractional gradient method) which the ISO standard uses. There are a number of recent threads in the Exposure section that discuss it's methodology. How a film is tested is directly related to the results. Anyone who thinks they are obtaining a film's "true" film speed with a gray card and exposure meter are misinformed.

To answer the OPs question. Because I have a calibrated sensitometer, I get the effective film speed from the sensitometric exposure when ever I do a processing check. It's not a separate procedure for me.

I much prefer the simplicity of a fixed-density criterion over the delta-x-criterion for practical testing,or better yet, just reduce box speed by 1/3 stop and go for it

 

[Bill Burk]

The Good, the Perfect and the Lazy - Sounds like the title of the movie Clint Eastwood would make about us.

I agree the simplicity of the fixed-density criterion gives a good benchmark. And I use it with the approximate 0.62 average gradient of the ISO parameters to fix that speed in mind.

For illustration, I mark my graphs with speeds at the fixed-density point. But when I get out and take pictures, I ignore the speed changes and stick with the speed I found at the ISO speed point. Delta-X justifies that as Stephen Benskin has shown: speed doesn't move much with development change when using the Delta-X criterion.

In other words, for simplicity, don't change exposure index for every planned change of development time. I think Beyond the Zone System went too far beyond calculating a different exposure index for each meter reading. That is overly complicated and counterproductive in my opinion.

It's OK to use 0.1 speed point for illustration, but in the field, I ultimately agree to running with a slight speed reduction. I like 2/3 stop, you like 1/3 stop. These recommendations are so close to each other that we could say we agree completely...

Ralph Lambrecht (or anyone who cares to pipe in), what's your opinion of the minimum useful gradient criterion (0.3 times the average gradient)? I think that's the point identified by the "first excellent print" studies, so systems (spreadsheets) should try to identify the minimum useful gradient.

This would be especially useful for Michael R 1974's low gradient developer.

But you know, ultimately the "first excellent print" criterion is the ruler of the land. In the case of special developers we may need to toss all the characteristic curve criteria and go all the way to the print series and pick the best print.

 

[georg16nik]

... draft of a new Standard which will very likely be officially approved soon by the ASA Sectional Committee PH2 on Photographic Sensitometry (M. G. Anderson, Chairman), the Photographic Standards Board, and the officials of the American Standards Association. In this proposed Standard, the level of the numbers used for rating black-and-white films is approximately doubled. Such a change would have the fleet of reducing the safety factor to one half its present value...

Yep, they doubled the box speed number, while the film emulsions stayed the same.
Even today, in 2015, most B&W films box speeds over-promise and under-deliver when it comes to real world film shooting - the easy fix is pretty much still the same - shoot by the old, pre-1960 box speeds.

Furthermore, something I've posted in another thread here, The Kodak essential reference guide for filmmakers (motion pictures) notes:

A word about film speeds
You probably know that motion picture films use exposure index (EI) to indicate speed. Although similar, EI is not the same as the ASA or ISO speed used for still films. EI denotes a somewhat conservative figure related to the higher quality requirements of motion picture film that must be projected onto a large screen. Typically the EI speed is about one stop lower than ASA or ISO. EI 500 film, therefore, is the equivalent of ASA/ISO 1000.
http://motion.kodak.com/motion/uplo...nce_Guide/kodak_essential_reference_guide.pdf

higher quality requirements hits home for me when I shoot most of my films one stop lower than ASA or ISO and print them in my darkroom.

 

[Stephen Benskin]

This graph shows the relationship of exposure to print quality from the first excellent print test. I've added the approximate points for the fractional gradient point, the current ISO speed point (it is determined in relation to the fractional gradient point) and 1/2 ISO, Zone System and the ASA speed prior to the 1960 standard.



The fractional gradient point defines the limiting gradient. The rest can be thought of as personal taste. A major problem with personal testing is that it is replete with experimental errors, questionable assumptions, and unknown variables. The ISO has meaning and for general purpose developers can be used as a reference from which to base a personal EI. The personal EI, which reflects taste and metering preferences, can be determined while doing practical photography.

Think about it. If you choose a personal EI anywhere in the Goldilocks' zone, how precise does your personal EI need to be.

 

[Stephen Benskin]

Yep, they doubled the box speed number, while the film emulsions stayed the same.
Even today, in 2015, most B&W films box speeds over-promise and under-deliver when it comes to real world film shooting - the easy fix is pretty much still the same - shoot by the old, pre-1960 box speeds.

Not the point. You implied there was conspiratory and nefarious reasons why the methodology was changed and clearly that is not true.

Furthermore, something I've posted in another thread here, The Kodak essential reference guide for filmmakers (motion pictures) notes:

higher quality requirements hits home for me when I shoot most of my films one stop lower than ASA or ISO and print them in my darkroom.

FYI, there are different requirements for positive material projected in a darkened room than for prints to be viewed in a lite room as well as different requirements for color and black and white. Not that the note in the link about underrating film isn't applicable to black and white, it included a distinction, "Although similar, EI is not the same as the ASA or ISO speed used for still films." Let's not forget the motion picture release print is multiple generations removed from the original camera negative and there's quality loss with each generation.



Finally, you are confusing film speed with personal preference again. Don't know if you noticed, but I'm not suggesting people should exposure at the ISO rating. It's the part of your argument that the film speed method is somehow wrong because you like to the results from underrating the film is what I find credulous.