When the HECK did ASA become ISO??

[JW Dewdney]

Okay- so we used to have this system. ASA film numbers. Typically, 100 (normal speed), 400, etc. etc... and we had a european system called ISO - where 100 ASA translated to 21 degrees ISO. Every doubling or halving of ASA speed would result in adding 3 or subtracting 3 to the ISO scale. Logarithmic scale. Simple enough. But in recent years, everyone's referring to what was PREVIOUSLY ASA as ISO. What gives? Sorry if I'm not on the bandwagon - guess I stopped paying attention years ago.

Can someone also give me the lowdown on granularity indices? According to what I've read/heard, Fuji NPS should be a much finer, more detailed film than Velvia 50 - which makes no sense to me.

Thanks so much, if anyone has any feedback opinions on these issues...!

[Oren Grad]

That's not quite right. The linear-scale American standard was ASA, while the logarithmic-scale European standard was DIN (Deutsche Industrie Norm). The new international ISO standard formally combines them in this sort of notation: ISO 100/21°. However, it's common practice to omit the logarithmic element, making it look as though the ISO system is just the same as the old ASA system.

[Ted Harris]

More arcane detail to follow on behind Oren. ASA stands for the American Standards Association (now American National Standards Institute) which, along with the National Institute of Standards and Technology (NIST .. former National Bureau of Standards), feed into the International Standards Organization ((SO). ANSI is industry based and private and sets voluntary concensus standards, NIST performs similar functions on an official basis for the USG; ISO sets international standards. It is not just film speed but everything from baseline measures of weight and length, etc. to composition of materials and accounting standards.

[Oren Grad]

The current version of the applicable ISO standard is:

ISO 6:1993 Photography -- Black-and-white pictorial still camera negative film/process systems -- Determination of ISO speed

[Oren Grad]

And on the color films, not only do measured granularities correlate only approximately with subjectively perceived graininess, my recollection is that there are technical reasons why measured granularity indices of negative and slide films cannot be directly compared. I'd have to do some digging to locate a specific reference on that for you - perhaps someone else here is more on top of the details.

[Helen Bach]

ANSI is the organiser of the ISO technical committee (TC 42) that prepares photographic standards, so ANSI is still heavily involved.

Reversal colour film speed: ISO 2240:2003
Negative colour film speed: ISO 5800:1987
Digital cameras: ISO 12232:2006

Best,
Helen

[Helen Bach]

A single number for RMS granularity doesn't tell you much. It would be better to show R, G and B granularities over the density range of the film. That would tell you a lot more than the single number, because granularity varies with density and layer. Fuji give the RMS granularity for a density of 1.0 above DMin for both reversal and negative colour films.

Contrast affects the appearance of graininess - so the granular appearance of negative film will be increased by most printing methods and decreased when printing reversal film. Assuming a typical print density range, the density range of negative film is magnified by printing (say 1.2 to 2.0), while it is decreased when printing reversal film (say 3.0 to 2.0).

Does that help?

Best,
Helen

[Ted Harris]

Laughing ..... JW, I hope that Oren's, Helen's and my posts have not drivenyou over the cliff .... although all are totally correct.

One more point on RMS granularity. The single number the manufacturers give you and Fuji makes so much out of in its marketing hype is still useful in comparing one film to another. OTOH today's films are all sooooo good in this respect.

[Kevin Crisp]

JW: This happend a long time ago, I'd guess as far back as 1980.

[Helen Bach]

The official birth of ISO film speeds could have been even earlier. TC 42 was in existence in 1972, and ISO arithmetic/logarithmic speeds were mentioned in the 1974 ISO standard for light meters that replaced the 1971 ANSI standard.

Best,
Helen

[Oren Grad]

Judging from my tattered collection of old issues of Popular Photography, the transition in popular usage occurred around 1983.

[al olson]

It should be noted that both the ASA and the ISO curves are log-log. That is the density (vertical axis) is the logarithm of the inverse of transmissivity and the horizontal axis is the logarithm of exposure. For data on the same film that curves are identical. This curve is referred to as the gamma curve, the G-bar curve, the G curve, as well as the characteristic curve.

What is different is how the speed point is determined.

ASA took the Average Gradient (AG) which more or less corresponds to the straight-line portion of the curve (over a log exposure interval of 1.5). Then it computes a line with a slope of .3 times the slope of the AG and finds the tangent point between this line and the toe of the curve. "The speed is computed by taking the reciprocal of the exposure value E [the exposure where the point of tangency occurs], in meter-candle-seconds, and rounding the result to the nearest step on a scale in which the steps differ by a factor of the cube root of 2, as 100, 125, 160, 200, etc."

This is from the Kodak Data Book, Kodak Films, 6th edition, published in 1954. It is interesting that in the 7th edition, published two years later, Kodak explains the gamma curve again, but leaves out the description of how the speed point is calculated.

The ISO calculation of the "Speed Point" is entirely different. Again, ISO works with the gamma curve. First, they measure "base plus fog" by developing unexposed film. This is because the film base reduces transmissivity and the unexposed emulsion will also produce a slight residual fog. The starting point adds a density of .1 [an arbitrary convention] to the density of base plus fog. "The film is then developed so that another point, which has received 1.3 log units more exposure than the starting point, is 0.8 density units (2 2/3 stops) darker than the base point. Then by dividing .8 by the exposure at the base point, you determine the arithmetic speed of the film ..."

This description is available in a number of sources, I simply took the liberty of quoting "The Black & White Handbook", 2000, Hicks and Schultz.

It is said by many photographers that the old ASA is more honest because it determines the speed point on the curve where the rate of density vs exposure is significant while films with a shorter than normal or a longer than normal toe can distort the true value of the film.

Unfortunately, the ASA values were difficult to calculate back in the days before computers were common. ISO is less complex to calculate, the method was used by the Europeans long before it was adopted by the Americans, and the resulting film speeds are usually similar. The differences are miniscule considering that we round the film speeds to the nearest 100, 125, 160, 200, 250, 320, or whatever, anyway.

It is interesting to note that the ASA system was devised by couple of photogrammetrists (?) Jones and Condit based on research by Hurter and Driffield a couple of English photogrammetrists who worked for a British subsidiary Kodak's back in 1895 (the gamma curve was often also called the D&H curve). Jones seems to get more credit than Condit for devising the ASA index.

In any event, the gamma curves for ASA and ISO are identical, they are simply plots of the density vs log exposure. The difference is in the methods for determining a film's speed index.

[al olson]

A couple of quick corrections from further research:

The characteristic/gamma/H&D/G-bar curve is also referred to in some quarters as the D/log E curve.

As a historical note, my date of 1895 was wrong, from further research I find Ferdinand Hurter, who was Swiss, and Vero Driffield, English, originated the science of photographic sensitometry in 1890, not 1895.

[Helen Bach]

ISO colour negative speeds are determined by simply taking the exposure for Status M 0.15 above fb+f in each of R, G and B then using

Hmean= (Hgreen x Hslowest)^0.5.

Best,
Helen

[David G. Gagnon]

My head aches

DG :D

[JW Dewdney]

JW: This happend a long time ago, I'd guess as far back as 1980.

Geez Louise...! I musta been in some kind of time bubble. Though I remember ASA being used in 1987 - so I'm not so sure about that. But the error in my post (& thinking) was that I was getting ISO and DIN mixed up. DIN was the log scale. I appreciate the info. It was something I paid attention to once upon a time - and since then, I'd just used my old standards...

As for granularity - well, I'd been looking at some sort of 'objective' measurement to be able to figure out a good film stock to use for scanning. Surely - scanning must be the great equalizer, regardless of channel-dependent granularity indices. Anybody know of a good experiment published online looking at detail and film grain comparing various neg & pos. films?

[Helen Bach]

...

As for granularity - well, I'd been looking at some sort of 'objective' measurement to be able to figure out a good film stock to use for scanning. Surely - scanning must be the great equalizer, regardless of channel-dependent granularity indices. Anybody know of a good experiment published online looking at detail and film grain comparing various neg & pos. films?

I wonder if there are too many variables for a useful objective assessment. Scanner type, samples-per-inch, type and degree of grain reduction and sharpening (the interaction between the scanned appearance of the grain and that software), varying contrast, varying placement on the characteristic curve, etc.

I just try a few films for myself with the equipment and processes I have available and am happy with using. I find that Pro 160S is effectively grain-free when scanned at 2000 ppi on a (rented) Imacon 949 and printed to 20x24 from 4x5 with no grain reduction applied.

Though I did it as an example of B&W conversion, here is an example of Pro 160S scanned at 2050 ppi. The full 4x5 frame, and about 1/300th of the full frame. The detail is a compressed JPEG at the original scanned pixel dimensions - approx 500 x 500. It is of the little plant tag/plant tombstone in the centre of the upper right quadrant.

Best,
Helen

http://gallery.photo.net/photo/4921836-md.jpg

http://gallery.photo.net/photo/4944823-lg.jpg

[John Kasaian]

I think there might be a legal firm named ASA, ISO, & DIN.

[C. D. Keth]

That's interesting how they're calculated, actually. I have a question for someone. Why do motion picture films use EI (exposure index) instead of ISO? It's the same number but on motion picture products, they print it as EI. I'm a cinematographer so I'm curious why they are doing it different when it's effectively exactly the same.

[Helen Bach]

Christopher,

I don't think that there is an ISO standard for the speed of motion picture negative films. ISO 2240 can be used for colour reversal films - though only if they are intended for amateur use.

In practice, I guess that mid-tone methods (eg LAD) are more relevant to cinematography than toe speed methods - but that is just my very selective observation. I use 18% aim density for establishing speed. Out of interest, what do you use?

Best,
Helen

[C. D. Keth]

I base my speeds on 18% grey. I almost always overexpose negative by 2/3 of a stop or a stop for the tighter grain pattern it yields, which is considerably more important when you have a linear enlargement factor of several hundred for projection rather than 10 or 20 for printing. In addition, the film will go through a couple duplication steps before it goes to release prints.

Generally, I start with the factory rating and just do a studio test where I shoot a greycard held by a lit assistant, a greyscale, in a room lit similarly to what I expect most of the movie to be like. I'll then bracket up and down a couple stops (making sure to have something labeling the bracket in the scene) each way in 1/3 stop increments. Then I'll ahve a film print made by the lab and ask them to correct the greycards in each scene to 18% neutral grey in the print. This will give me a baseline reference constant to each bracket. I'll then project the test to judge the results (projecting is essential because film grain looks very different in a still as opposed to randomly changing 24 times a second.)

Anything else you're wondering about? :)

[Helen Bach]

Thanks Chris,

That's not entirely dissimilar to LAD - the difference being that with LAD you decide on the optimum density for the 18% exposure and work from there. Anyway, it illustrates the point that in cinematography midtone exposure is the common way of determining speed, rather than toe exposure, and that we don't need an ISO speed. I've been a DP since the mid-70's, by the way.

Best,
Helen

[C. D. Keth]

Exactly. It's not the most scientific way of testing but it works fine for me :)

You should ahve mentioned your profession, my post could have been half it's length without some explanation :P I didn't know if you were familiar with motion picture post or not. What sort of things do you generally shoot lately?

[Jonathan Brewer]

My understanding/concept is that EI and ISO ratings are different, ISO/ASA rates film by itself, use a filter/polarizer et al, you rate the film at another speed, a film normally rated at ISO 400 has an EI of 100 when used w/an orange 21 filter.

'I don't think that there is an ISO standard for the speed of motion picture negative films'......................yes there was, since the days before 5254, one of the first modern motion picture negative films, a film I loved and loaded in my 35mm camera via 'short ends' I'd load from my 'ice box'. This was a film so good, I never understood why they changed to 5247 and on and on.

In terms of the EI issue, go outside w/color neg motion picture film, traditionally, the Asst.(if they've been working together for any length of time) didn't need to be told by the DP to slap on the 85B to correct for daylight, which naturally changes the speed, when I think of the speed of a film, w/no filter, no nothin, I think of its ISO speed, EI for me considers filters, changes the shutter on a MP camera from 180 to 90 degrees et all.

Just check out the old Asst. Cameraman manual/handbook by the husband and wife team, the Carlsons, it's all in there, H&D curves/ASA ratings.

[Helen Bach]

...
'I don't think that there is an ISO standard for the speed of motion picture negative films'......................yes there was, since the days before 5254...

If there is an ISO for motion picture negative film please tell us the number. Why does David Samuelson quote EI instead of ISO in his Manual? Why does he say "There is no official standard for motion picture color negative film speed measurement"?

Why does the ASC manual say "While ASA film speeds do not apply directly to motion-picture films...

All film manufacturers furnish EI numbers related to commercial exposure meters as a recommendation for a starting point in determining optimum exposure."

As you say, EI is not ISO. ISO is a standard, EI is not.

Best,
Helen

[Jonathan Brewer]

Let me clarify a couple of things, 5254 and later, 5247, were references to Kodak films, when Kodak pretty much dominated the films shot in hollywood, and they were processed by the Technicolor outfit, later Fuji came on to challenge Kodaks dominance, and they other folks got into the act, regardless..........................at that time, the DP or the gaffer/head electrician(who works for the DP), would each have a meter and play around w/the film speed and/or ASA values.

Sometimes to tweak/change/correct what the did/missed/wanted to change, they call the lab/write out instructions as to color corrections, and an increase/decrease in exposure in terms of 'points' in an effort to 'time' the film, 8 points was equal to a stop.

An old camera like an arri doesn't have a shutter like a still camera, its shutter is shaped like a circular disk, you can adjust its shape to open or close it, since it spins, whether there's a smaller wedge in the disk allowing light to get to the film, or you've adjusted this disk so it looks like a 'half moon', determines how much light gets to the film.

Adjusting this shutter for example/opening or closing it/changing it shape as it spins, means opening or the closing the shutter in terms of degrees, so many degrees, so much of a stop.

[Jonathan Brewer]

I entered the Producers Guild trainee programs for Asst. Cameraman, 10 positions were available, 5000 people took the test as USC, 70 interviewed for the 10 trainee positions, I made it to of one of the 10 positions, you were a trainee for a year(@ $600.00, and if you passed successfully you got a card in Local #659(that's what it was called back then, as a trainee, you got the Carlson handbook, which says what I say it says,....................if you don't believe me, get the book, it was bought and used extensively by the Assistants I worked with when I was a trainee, when you became a trainee, you went down to Larry Edmunds in Hollywood and got the book.

The Directors of Photography I watched while functioning as a trainee, and working later as a 2nd Asst. and then rerating to 1st Asst. rated their films in terms of an ASA rating, some of the folks I trained under would be Fred Gately('Docters Hospital'), and Gerald Perry Finerman(DP on the first 'Star Trek', I had a chance to audit a lecture at the American Film Institue by George Folsey('Green Dolphin Street', 'Forbidden Planet').

Now please read what I said, ASA what was used then not ISO, ASA was what was used by these folks when I trained w/them, the ISO term/concept came later, but these folks to a man used the concepts in the Carlson book manual, and they all/all of their Gaffers used Spectra's and played around w/ASA ratings to get exposures.

Also check on the old 5254 and 5247 Kodak motion picture neg. films, they had an ASA rating which the Cameramen of that time period used. Now, I'm not making this all up.

Again I didn't say what you're suggesting, EI and ISO the way I learned it, was to distinguish between a films native speed, and its Effective Index when its sensitivity to light was being affected/changed/cut down by a filter, a change if the shutter et al, which is the whole idea behind EI versus ISO, an ISO 400 film HAS an effective speed(Exposure INDEX) of 100 when you use an orange filter, period. Configure a MP camera's shutter from 180 to 135 degrees, you change the amount of light hitting the film, the changes in filtration/shutter et all thus become EV(exposure values, so you can think of an EI(a different speed to use), because you've slapped on a filter, or you can think of EV(exposure value), or simply consider the native ASA/ISO speed of a film, and adjust your exposure, simple as that, THAT'S WHAT THESE FOLKS USED, and how they taught me, so if you going to dispute that/don't believe it, get the Carlson book, and I will rest my case.

[Jonathan Brewer]

OMT....................I don't disupute how you learned, or what is says your book, but I due dispute your blanket generalization about these films not having an ASA speed, they did.

[Helen Bach]

Jonathan,

I think that you misunderstand something. I am well aware that we set our meters to 'ASA speeds', but the point is that there is no official standard for MP colour neg film speed - and I'm not the only person saying that. That is the point we were discussing, in answer to Chris' sensibly curious question. If you know of a standard, please tell us. Please also tell the ASC, 'cos what do they know?

Best,
Helen

PS I've just looked in the Carlson's book - they quote recommended exposure indices, not ASA ratings.

[C. D. Keth]

I'm not debating that they did have an ASA rating. They had one recently, even. I was wondering why they don't have one now. I'm not looking for a history lesson, I know all that stuff, trust me.

If ISO and EI are different things, then why, when I go to Kodak down the street (I'm not kidding, I'm in Rochester ;)) and buy a can of 5218, does it say "EI500?" Kodak sure isn't going to tell you the speed of the film with a 90 degree shutter, an 85 and a pola in the equation. That's retarded. They're going to tell you the speed of the film bare-assed naked, so to speak.

[Jonathan Brewer]

"That's retarded.'...............Please show your ass to anybody but me, I've addressed everybody in this thread with respect, I wouldn't bother to give you a history lesson, because I wasn't talking to you, I was responding to Helen Bach. Films used to have an ASA rating, now it's ISO, YOU, I repeat you, calculate, Exposure Indexs, or determine Exposure Value,...............what's retarded is the 'ass ugly' personal comments,............read what I said...................you can manipulate exposure two ways, you can incorporate a change in the light hitting you film and give it an EI, or you can leave the nominal film speed rating alone, and adjust/compensate your exposure by changing the shutter etc, which is Exposure values, one way or the other.

On the issue of ASA ratings, with all due respect, you're plain wrong on that, it boggles the mind you'd suggest that kodak wouldn't supply an ASA rating when they manufacture a film, check out the specs on the old 5254 or 5247 films.

'Please also tell the ASC, 'cos what do they know?'....................spare me the snide personal comments to undercut what I'm saying, I don't appreciate it. I read the magazine just like you do.

You're now saying something a little different than what you first said, you didn't mention Exposure Indice when you made your first statement, now that you've checked you mention EI rec. but insist/now you're 'massaging' it to it wasn't official, I disagree with how you're characterizing this, and yes everybody I worked for/learned from had out their Spectras, to do what I suggested they did, they didn't use their Spectras to comb their hair.

I've disagreed with you vigorously, I don't think I've gotten insulting and/or snide with anybody and I'll demand the same treatment back, if not, don't bother responding to my posts.

[Helen Bach]

Jonathan,

I haven't changed my story - film manufacturers quote EI not ISO because there is no ISO for motion picture colour negative film speed. That is a simple fact, not an opinion. A manufacturer cannot quote a standard speed when there is no standard. I mentioned the ASC because they say the same thing, and you dismissed the reference rather off-handedly. Even the book you referred to quotes exposure index for films rather than ISO or ASA.

If you know of an ASA or ISO standard, please quote it.

5247?
Here's what Kodak say:

"Exposure Indexes

Tungsten (3200K) - 125/22 Daylight1 - 80/20"

5254?

"EASTMAN Color Negative film, 7/5254. Tungsten, EI 100."

Best,
Helen

[Jonathan Brewer]

You haven't changed your story???...........................then I need to go have my eyes checked. You said this earlier...........................................'I don't think that there is an ISO standard for the speed of motion picture negative films'....................there was nothing in this about EI, but after you checked whatever you check, you then change it to this/add.................................'film manufacturers quote EI not ISO because there is no ISO for motion picture colour negative film speed.'.

The..................'film manufacturers quote EI'............part of the last statement wasn't in the first statement, and you'd didn't say this until after I suggested you check out what I was saying, and you then suggesting that it's not really official, that is a difference WITHOUT a distinction.

IS0 ratings did not exist with the advent of Kodak 5254, but I suggested to you that there was an ASA rating with these two films I mentioned, because I think it needs to be said that regardless of whether it's talking about ISO or it's predecessor ASA, and despite it's disclaimers in its spec sheets, kodak provided you with a film speed, whether or not it's official is you saying that. If you called up Kodak and asked the film speed of 5254 or any of the later films, you were given a number, the Directors of Photograhy mostly used their meter rating the film at that number, and then Technicolor would process for that rating, again, the people who taught me used it as 'Gospel', I'll simply stand on what I said and leave it at that.

[Helen Bach]

Jonathan,

The original question was

Quote: "Why do motion picture films use EI (exposure index) instead of ISO? It's the same number but on motion picture products, they print it as EI."

My answer was that it is because there is no relevant ISO. No need to mention EI in the answer, because it has already been mentioned in the question.

Though this discussion is about what there is now, I would be interested to know of a standard that existed in the past. So far you have not come up with a single piece of evidence despite repeated requests. If it exists, please enlighten us.

Yes, the number that Kodak gives is a film speed, and it is numerically equal to a standard speed ("It's the same number ..." as Chris wrote), but it is not a standard speed because there is no standard. That's why they call it an EI rather than an ASA or ISO. Nobody has a problem with that. Of course people refer to '100 ASA' films on set - it doesn't matter in practice. But that wasn't the question. I tried to explain that a few posts back.

Best,
Helen

[Jonathan Brewer]

"Yes, the number that Kodak gives is a film speed'..............................yes, exactly, and in terms of the films that existed before the ISO standard, this is exactly what they did, if you called up Kodak on the phone and asked them the ASA rating of 5254, they'd give you a number, and that's how the folks used it ..................................so a discussion about ISO as it relates to a film like the late 5254 doesn't mean anything.

I don't know how I can make this any clearer, you made a blanket statement refering only to MP film and the ISO standard, and I've suggested to you that this was dealt with another way before that standard came out, and you keep 'skipping' over this point.

I don't need to prove/give you any proof, this is simply the way it was in the period around the time of 5254, when dealing w/5254 folks would light w/their Spectras set up for Kodak's rating, and this was when 5254 was the only game in town, do you know of anyone that did otherwise, everybody lit 5254 and 5247 according to Kodaks rating, and this was BEFORE the ISO standard came into existence, and you hadn't included these qualifiers in your statment.

[Helen Bach]

Jonathan,

I honestly believe that you have misunderstood the point of this discussion, and I have tried to point this out before. Please read the original question. Everyone understands that ASA and ISO speeds are what we set our meters to, and that EI and ASA/ISO are effectively the same. The question was why the manufacturers don't call it 'ISO'. My original answer is perfectly correct. The manufacturers can only call it ASA or ISO if there is an ASA or ISO standard for the speed of motion picture colour negative film. There is no standard. That is not a matter of debate. The ASC manual says that. David Samuelson says that. The ISO say that by not having a standard. There is no ISO standard for the speed of motion picture colour negative film so it isn't a matter of what happened before ISO, it is a matter of what we have always done. The manufacturer suggests an EI, we test for the speed if that is our way of doing things, then we set the chosen speed on our meters which are calibrated in ASA or ISO film speeds. The meters are calibrated in ASA or ISO speeds, because there were/are ASA and ISO standards for meter calibration.

We can call film speed what we want. The manufacturers can't. That is what this discussion is about.

Best,
Helen

[C. D. Keth]

"That's retarded.'...............Please show your ass to anybody but me, I've addressed everybody in this thread with respect, I wouldn't bother to give you a history lesson, because I wasn't talking to you, I was responding to Helen Bach. Films used to have an ASA rating, now it's ISO, YOU, I repeat you, calculate, Exposure Indexs, or determine Exposure Value,...............what's retarded is the 'ass ugly' personal comments,............read what I said...................you can manipulate exposure two ways, you can incorporate a change in the light hitting you film and give it an EI, or you can leave the nominal film speed rating alone, and adjust/compensate your exposure by changing the shutter etc, which is Exposure values, one way or the other.

On the issue of ASA ratings, with all due respect, you're plain wrong on that, it boggles the mind you'd suggest that kodak wouldn't supply an ASA rating when they manufacture a film, check out the specs on the old 5254 or 5247 films.

'Please also tell the ASC, 'cos what do they know?'....................spare me the snide personal comments to undercut what I'm saying, I don't appreciate it. I read the magazine just like you do.

You're now saying something a little different than what you first said, you didn't mention Exposure Indice when you made your first statement, now that you've checked you mention EI rec. but insist/now you're 'massaging' it to it wasn't official, I disagree with how you're characterizing this, and yes everybody I worked for/learned from had out their Spectras, to do what I suggested they did, they didn't use their Spectras to comb their hair.

I've disagreed with you vigorously, I don't think I've gotten insulting and/or snide with anybody and I'll demand the same treatment back, if not, don't bother responding to my posts.


Jonathan, I never used the word 'retarded' in any relation to you. The ass comment was in no way directed at you, or anybody else for that matter. I never insulted you, nor was I snide with you. Please extend the same courtesy to me and DO NOT EVER twist my words around again to make me look stupid. Your attempt to belittle me worked rather poorly anyway, if I say so myself. I am not returning to this thread because, for one my question has been answered logically and thoroughly by Helen. Also, I am sick of your inane babbling, poorly supported truths, and insults. Because I am not returning, you needn't bother with a response. Have a fine evening, Sir.

[Jonathan Brewer]

Read it again??? don't think so, I understood it the first time, several hours ago, the discussion is what everybody discussed including our exchanges, and as to how they did it before ISO came into play, which you didn't address, the original issue notwithstanding.

Don't you think that folks considering our exchange got a different perspective/additional info on this and motion picture film, and how it was rated and exposed, than just a blanket generalization regarding MP film and the ISO?

I've tried to suggest by how they addressed this before the idea of an ISO standard, that whatever you call a rating, or insist that since the manufacturer calls it an EI that it's not official, or that whatever it is it can't be ISO, it just doesn't make any difference, and it didn't make any difference to the Cameramen who worked with various films when there was no ISO standard.

I think what I've said applies in context, and within the framework of the discussion, and if we're mis-communicating so be it, but this statement is just plain wrong............................
..................."There is no ISO standard for the speed of motion picture colour negative film so it isn't a matter of what happened before ISO,".......................What happened before ISO, were some great/monumental achievements in Cinematography, it doesn't matter to you, it does matter to me.

Now unless you can read minds Helen, please don't speculate on my understanding of all this, we can agree to disagree and hopefully folks can judge for themselves, but I stand on this, I didn't see a reason to get rid of the ASA standard, and I don't think that whether there was, or wasn't an ASA/ISO standard made one bit of difference to the individual Cinematographer, in the past, or present, and I don't care what it is or isn't, all of these are starting points, ratings you can accept or reject, all of them, you can talk all night, you aren't going to convince me that HP5 is ISO 400, I think ISO 320 is more accurate, but since they're sticking w/400, I shoot at an EI of 320.

Now I'm going to retire w/my wife so we can have a long discussion about her Tulips growing in the back yard, C ya later.

[Jonathan Brewer]

Christopher Keith.................... live with it,.......get lost, .....you twisted your own words, now go nag somebody else.

[Helen Bach]

"There is no ISO standard for the speed of motion picture colour negative film so it isn't a matter of what happened before ISO,".......................What happened before ISO, were some great/monumental achievements in Cinematography, it doesn't matter to you, it does matter to me.

Jonathan,

You have misunderstood what I am writing, and you have twisted my words. "It isn't a matter" and "It doesn't matter" mean two very different things and your rewording seems to me to be wilfully antagonistic, especially as my original words were "...it isn't a matter of what happened before ISO, it is a matter of what we have always done."

The is no 'before and after ISO' in terms of MP colour negative film speed ratings or practical cinematography because there is no ISO for MP colour neg films, so there is no 'after'. In practice we do what we have always done, more or less.

I haven't said that a manufacturer's EI is not 'official' (another example of you twisting my words, for example "you then suggesting that it's not really official"). I have said that it is not a standard speed because there is no official standard. Saying that 'there is no official standard' is a statement of fact, not a statement of my opinion. In one of my early posts I mentioned that I used LAD. Though 'official' isn't a word I would want to use in this case, LAD is a good example of a clearly defined, repeatable, standardised method for determining the speed of MP colour neg films, but it isn't an ASA, ANSI or ISO standard.

Next example of twisted words: I suggested a few times, in an attempt to explain the apparent contention, that I thought that you had misunderstood the point of this thread, and that you should re-read Chris' original question. That is not the same as saying that your "understanding of all this" (your words) was deficient.

My opinion is that you have misunderstood what I am trying to say, and in doing so you have found contention where none exists. What should have been a simple explanation of the curious practice of manufacturers quoting EI instead of ISO has turned into trench warfare, for no real reason that I can see. The EI/ISO thing is not that big a deal, nor does it have any bearing on practical cinematography. Had we continued to discuss methods of determining film speeds in general by using mid-tone methods instead of toe speed methods it could have been worthwhile.

Best,
Helen

[Jonathan Brewer]

Again, spare me the mindreading, I gave you my perspective on this..........there were some great achievements in Cinematography by people who never heard of an ISO, from my perspective the ISO standard is a non-issue.

I'm not antaganistic toward you, your suggestion that I am is giving yourself too much credit, very respectfully, but also very frankly, I don't care about you one way or the other. I think the thread speaks for itself for itself.

'The EI/ISO thing is not that big a deal, nor does it have any bearing on practical cinematography.'................................this is the most reasonable thing you've said, which simply should have been said upfront, it's what I've been suggesting all along, it's extremely important to a discussion about ASA/ISO, I think it's a more relevant declaration that what an ASA or ISO is or isn't, and whatever they are, they're no big deal.

As I've already said, when I disagree w/you, I may disagree w/you vigorously, you've gotten snide with me in this thread, that also is not big deal, we both gave and we got, but if you're going to take personal and that's all you get from what I've said, then simply don't respond to my posts.

[Helen Bach]

Again, spare me the mindreading, I gave you my perspective on this..........there were some great achievements in Cinematography by people who never heard of an ISO, from my perspective the ISO standard is a non-issue...

I think the thread speaks for itself for itself.
...

Jonathan,

I share your sentiment that the contributions made to this thread speak for themselves.

I am unaware of a relevant ISO, so if at a later date you feel able to tell us which ISO you are referring to I would be genuinely interested to learn of it. As far as I'm concerned we don't need no stinkin' ISO to tell us what to set our meters to.

I apologise for coming across as being snide. That was not my intent - I hoped that the reference to telling the ASC would introduce some levity, but I was mistaken. I did not take anything you said personally - not because I don't care about what you think, but because I regard this as a purely technical discussion of no great importance. I also see less disagreement between us in this discussion than you appear to see.

Best wishes,
Helen

[Jonathan Brewer]

'As far as I'm concerned we don't need no stinkin' ISO to tell us what to set our meters to.'.......................

.....................................'Treasure of Sierra Madre' was one of my favorite movies Helen, hell of a movie wasn't it? And it was shot w/out the benefit of an ISO standard, but since you don't believe like I do, that the EI/ASA/ISO issue isn't really that big of deal, how bout we both leave this thread on an upbeat note.

Ciao
Jonathan

[raucousimages]

For all practical purposes ASA=ISO. Get over it.

[Helen Bach]

...but since you don't believe like I do, that the EI/ASA/ISO issue isn't really that big of deal...

No Jonathan, you are completely wrong about my views, I don't think that it is any deal at all: that's what I've been saying. There is no standard (a fact), and it doesn't matter at all because we determine our own speeds. That is what I have been saying all along. I tried to tell you that you had misunderstood my point.

Best,
Helen

[Jonathan Brewer]

That's on the money, asa=iso pretty much, so just get over it, I'm gone, I've got better things to do.

[Helen Bach]

...EI and ASA/ISO are effectively the same...

At least we agree on something.

Best wishes to all.
Helen

[Jonathan Brewer]

'Kodak generally determines the speed ratings for films using ISO speed rating methods'........................................................................................



................................You know I was gone from this thread, but admittedly part of my interest had been further 'piqued' by the discussion, so I went to the horses mouth, Kodak, the above phrase Helen, and for anyone else interested, is from this Article: ISO vs EI speed ratings for Kodak films, and I'll comment on what I get from it, although by all means read it yourself.

Kodak has always given a film speed, and actually this article spells out why they choose to label that number an EI vs a particular ISO AND I would suggest, ASA numbers before the ISO standard came along, and Kodaks reasoning in this article is right on the money, as in their example of the possible need to 'push process' part of a roll in deciding when to label a film w/an EI as opposed to an ISO speed.

Rereading some of the thread, I mis-spoke at least twice saying ISO when I meant ASA, I don't think that changes what I meant, and I think this article clears it up for everybody, since it discloses the why, it doesn't make any difference whose right, but I would suggest from my perspective that the numbers as we've all agreed are pretty interchangeable, the variables Kodak considered for the change from an ISO number to an EI notwithstanding. And the article is official.

I'm glad I found the article because I think it explains the issues for everybody.

[Helen Bach]

Here's a link:

CIS-185 (http://www.kodak.com/global/en/professional/support/techPubs/cis185/cis185.jhtml)

I read that document a while ago, and understand it perfectly. It is about still films, not MP film, so it isn't really relevant to this discussion. There are ISO standards for still film, just as there were ASA standards. There are no ISO standards for MP film speed, but Kodak could use still methods to determine the EI if they wanted to (they don't, as far as I've been told by the guys at EK when I worked with them on the LAD method), they just can't quote ISO speeds for MP colour neg because there is no ISO standard. That isn't explained in CIS-185, because CIS-185 is not about MP film. The EI ratings that EK give for MP film are for normal ratings for standard processing, so non-standard processing isn't the reason.

Jonathan,

Why didn't you leave this thread on the agreeable note that it was on? The fact that you refer to CIS-185 as an explanation makes me think that you don't understand what we have been talking about. Sorry.

Best,
Helen

[Jonathan Brewer]

You just don't have any understanding, if you read the article, it doens't say anything about still versus MP film, it talks about film period. Kodak doesn't say that in the article, if fact it doesn't mention a difference between still photography and motion picture film, the article talks about the reasons behind EI versus ISO, not just testing, which I believe in, but as hedge against consumers who don't test, and everything else in the article.

Where does Kodak specify not having a standard for MP film?

There is a standard, read the first sentence of my post, Kodak points it out. There's no difference between an EI for MP and film intended for still photography, and Kodak points out how they come up w/their EI in black and white, the SAME WAY they come up with their ISO, numbers.

ISO numbers are often inaccurate, HP5(a still film) w/an ISO of 400 is really 320 from my tests, which approaches half a stop off, you test with any film you're not sure of.

I'll make this short and sweet, please show where Kodak, the folks who MAKE the film specify that there are ISO speeds in regards to Color neg MP, because there is no ISO standard, and this will be my last word on the matter and I will go onto other things, because the article does mention a standard/standardization of how they derive both numbers.

[Jonathan Brewer]

Quit the bating, I'm not responding to that, I read the article, posted it here, please answer my points regarding my perspective on it vs yours.

[Jonathan Brewer]

Here's the first third of the article, and it talks about standardization and repeatability. Comment on it and not on me please.......................



.....................Kodak generally determines the speed ratings for films using ISO speed rating methods. However, ISO speed ratings are determined under one set of very specific conditions. Sometimes those conditions, while highly standardized, do not correlate as closely as desired to real world conditions. This can be due to a number of circumstances including, but not limited to:
1. The specified process conditions for determining ISO speed are defined for repeatability and standardization, but may not be representative of the process conditions commonly used in the trade. This is especially true of black-and-white films because of the diversity of developers available.
2. Standard film speed determination is usually based upon a set of specifically defined criteria. Those criteria may not always be consistent with optimum quality or best practices for a given photographic system or common application. There are several circumstances where this may apply:..............................

...................The article is pretty long winded, so I didn't copy and paste all of it, I think it does speak of a standard, AND the considerations of when Kodak varies from it.......

[tim atherton]

I'll make this short and sweet, please show where Kodak, the folks who MAKE the film specify that there are ISO speeds in regards to Color neg MP, because there is no ISO standard, and this will be my last word on the matter and I will go onto other things, because the article does mention a standard/standardization of how they derive both numbers.

That's easy, go to the ISO site and find the ISO Standard for determining Motion Picture Film Speed as opposed to the standard for determining Still Photography Colour Negative/reversal film speed and post the link here when you find it.

[Jonathan Brewer]

I'll check it out, certainly, but that's not what I asked, I asked about the Manufacturer's method and standardization for their film speed ratings, Kodak's product and Kodak's films and how they rate their own film....................Kodak's already said they do this....................'Kodak generally determines the speed ratings for films using ISO speed rating methods'.

[tim atherton]

to make it easier, here's

ISO 5800:1987
Photography -- Colour negative films for still photography -- Determination of ISO speed

http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=11948&ICS1=37&ICS2=40&ICS3=20&scopelist=

(ISO note regarding the above: The specifications do not apply to colour negative films for motion-picture and aerial photography.)

So now just match it with the equivalent standard for Motion Picture Film:

(you can do it easily by running an ISO search for "Determination of ISO speed")

[tim atherton]

I'll check it out, certainly, but that's not what I asked, I asked about the Manufacturer's method and standardization for their film speed ratings, Kodak's product and Kodak's films and how they rate their own film....................Kodak's already said they do this....................'Kodak generally determines the speed ratings for films using ISO speed rating methods'.

exactly - they use the globally recognised ISO standard but I think you'll find - if you search the ISO standards - that there is no standard for Determination of ISO speed for Motion Picture Films - ergo Kodak cannot be using the ISO Standard for determining the speed of motion picture film....

So however it is they may be determining and describing the "speed" of motion picture film, it isn't by using ISO

[Jonathan Brewer]

I've clicked your link, and nothing comes up, and when I type it in there are a million articles, by all means steer me to a link Tim, I'll honestly look for it, but as I said, Kodak makes it, derives their film speeds per the article, even if there's nothing from the ISO folks, the motion picture color negative film exists, and Kodak provides a film speed that works.

[Jonathan Brewer]

I disagree...............Kodak says this..............................'Kodak generally determines the speed ratings for films using ISO speed rating methods.'.........and they make the film, and the film speeds they supply with those films work, which is why can incorporate those values in your meter. If they were'nt right, if Kodak isn't doing what they're saying, the ratings wouldn't work, and I don't believe that.

And films w/an ISO rating can be way off, what do you rate HP5 at(yes it's a film for still photography)? The 400 that's on the box? It's more like 320 from my tests.

Another thing, the article mentions testing, I do that, not just Helec Bach, I also test like many folks here on films w/an ISO rating(yes still film), some of them are off, how many people rate HP5 @ ISO 400.

It's the documention of the folks who set up the standards, versus the folks who make the product, you haven't convinced me, if kodak said there wasn't any standard then I stand corrected, but I don't agree.

[Helen Bach]

...
I'll make this short and sweet, please show where Kodak, the folks who MAKE the film specify that there are ISO speeds in regards to Color neg MP, because there is no ISO standard, and this will be my last word on the matter and I will go onto other things, because the article does mention a standard/standardization of how they derive both numbers.

Oh, OK, if you insist:

"Why is the speed rating of motion picture camera films given in Exposure Indices rather than ASA or DIN values?
There is no ANSI standard to determine the speed of these films.
The speed of motion picture camera films and the suggested filtrations are determined on the basis of practical picture tests. Suitable safety factors have been included to allow for differences in cameras, variation in lighting, etc. The exposure index values should not be regarded as numbers which express the absolute speed or sensitivity of the film, neither should they be regarded as fixed values which can not be changed if the results of repeated tests indicate the need for such changes."

Here. (http://www.kodak.com/US/en/motion/support/faq/index.jhtml?id=0.1.4.15.16&lc=en#preprod8)

And just in case you query the difference between ANSI and ISO, ANSI are the leaders of the ISO technical committee on cinematography.

You didn't believe me, you didn't believe David Samuelson, you didn't believe the Carlsons, you didn't believe the ASC, will you believe EK?


Best,
Helen

[Jonathan Brewer]

OMT.............................you're telling me you can personally test to come up with a reliable number for a film, but Kodak who makes this stuff can't????????????................I don't agree.

[Jonathan Brewer]

I believe Kodak's claim, no one has shown me anything that invalidates that claim and Samuelson doens't make Kodaks product.

[tim atherton]

but as I said, Kodak makes it, derives their film speeds per the article, even if there's nothing from the ISO folks, the motion picture color negative film exists, and Kodak provides a film speed that works.

well, not quite, as has been pointed out many times, Kodak provides and EI for their motion picture films - their testing methods for which aren't defined by a recognised universal standard (nor, with relation to moiton picture film, fully described), as opposed to an ISO rating, which is. Kodak's EI for a particular film may usefully relate to the ISO Film Speed standard on - say - light meters, but are not defined by that standard.

Kodak describes it as:

Exposure Index
The film exposure index (EI) is a measurement of film speed that can be used with an exposure meter to determine the aperture needed for specific lighting conditions. The indexes for KODAK Motion Picture Films are based on practical picture tests but make allowance for some normal variations in equipment and film that will be used for the production. There are many variables for a single exposure. Individual cameras, lights, and meters are all different. Lenses are often calibrated in T-stops. Coatings on lenses affect the amount of light that strikes the emulsion. The actual shutter speeds and f-numbers of a camera and those marked on it sometimes differ. Particular film emulsions have unique properties.

Camera techniques, as well as the lens and lighting, can also affect exposure. All of these variables can combine to make a real difference between the recommended exposure and the optimum exposure for specific conditions and equipment. For these reasons, it is always wise to test several combinations of camera, film, and equipment to find the exposures that produce the best results for your operation. Exposure index figures are applicable to meters marked for ISO (International Standards Organization) or ASA (American Standards Association) speeds, and are used as a starting point for an exposure series.

(gotta love this pinhead/angels stuff....)

[Helen Bach]

I believe Kodak's claim, no one has shown me anything that invalidates that claim and Samuelson doens't make Kodaks product.

Which claim? Having seen Kodak's words:

"Why is the speed rating of motion picture camera films given in Exposure Indices rather than ASA or DIN values?
There is no ANSI standard to determine the speed of these films."

are you now satisfied that Kodak quote EI instead of ISO for MP colour neg because there is no relevant ISO?

You wrote: "...please show where Kodak, the folks who MAKE the film specify that there are ISO speeds in regards to Color neg MP, because there is no ISO standard, and this will be my last word on the matter..."

We've shown you where Kodak explain that there is no ISO standard for MP colour neg , but you haven't kept your side of the bargain. Please keep to your word.

Best,
Helen

[tim atherton]

ISO numbers are often inaccurate, HP5(a still film) w/an ISO of 400 is really 320 from my tests, which approaches half a stop off, you test with any film you're not sure of.


Do you find "your" film speed by following the ISO standards for testing and determining film speed?

[Jonathan Brewer]

I don't know where you get the Carlsons, they don't dispute any of this, and I've met them, have you???? When they did their own projects they slapped kodaks rating into their meters without much change.

Yes, yes, disclaimers, here's a number,...................... but you're on your own if you mess up, I've seen several cameramen use motion picture negative film, some would meter whatever they lit/whatever shot @ Kodak's rating, and everything would turn out perfect, no timing need @ the lab. Others would do tests, like John Alonzo(or so he related to trainees), every time he did another film, and even if he was using the same film, his reasoning, if memory serves me right was to fine tune adjustments due to differences in batch/cut, then insuring that everything shot for that film was the same batch.

Some DP's get on the phone to ask kodak about a particular batch, and it's performance, and Kodak's tightness of controls regarding it's products. None of these folks were 'slouches', they had to do it right, or they didn't eat.

Bottom line, many didn't have time on a series, shooting 16hrs a day to complete an episode in one week, to test, when they didn't have the time, they went by the film speed Kodak gave them.

There's taking what some folks say is 'Gospel' because it's written down somewhere, and there's experience working with this stuff, and working with this stuff, it works, Kodak's numbers work.

[Jonathan Brewer]

'Do you find "your" film speed by following the ISO standards for testing and determining film speed?'....................no I didn't.

Again, there not being an ISO standard from the ISO, doesn't mean anything, real world experience does, and what the folks do who make the film, some of the Directors of Photography that I've been privileged to watch, were magicians, some came in 'cold' at the last minute, because the previous guy had been fired, come onto the set, look at the script and rehearsals the same day, and take a drab, damp, and moldy set, and use their skills and turn the set into another world, and they had to get it right the first time, not like still photographer doing their own personal work where you don't like it, you throw it in the trash and start over, these folks didn't have that luxury, they knew their shit and so did Kodak. Many in the above scenario only had time to slap in the 100 slide for 5254 for metering purposes and start winging, watch 'dailies' the next day, you could see some magic, that is, some of these guys were so good, the stuffed didn't need to be times by the lab!!!!!!

[Jonathan Brewer]

I've gotten all this out of my system, and I'm outta here to help the kids w/their homework, but I have a suggestion for you, get some 'shorts ends' from folks who sell 'short ends', load it up in a 35mm camera shoot something outside, shoot it pretty much straightforward(no tricks), process it somewhere/someplace/at some lab that can process, per Kodak's rec., unless they've slacked up since I've been in it, it ought to be on the money, and as much on the money as some ISO films can be off the money, then come back here and tell us how the film performs.

It's been fun but I gotta run.

[Helen Bach]

Jonathan,

I find your last post objectionably condescending. ("...I have a suggestion for you, get some 'shorts ends' from folks who sell 'short ends', load it up in a 35mm camera...") Can I use my Aaton, or do you want me to use a still camera?

Nobody has suggested that the EI that Kodak give for their films is unusable. I don't know where you have got that impression from. That is not what we have been discussing.

I've been a DP since the early 70's. I've worked with EK and carried out practical speed tests of new MP films for them, possibly because EK thought that I knew my shit, as you put it.

You decided to contradict me when I explained that EK (and everyone else) quote EI not ISO for MP colour neg film because there is no ISO for MP colour neg films.

Since then you haven't offered one single piece of evidence to support your case. You have introduced many red herrings.

Tim and I have quoted EK's explanation of why they state EI instead of ISO - you promised that if we offered that evidence you would stop posting. You didn't keep your word.

I believe that there is more than enough information in this thread to let any venturesome reader make their own minds up, and see no point in continuing this discussion with you.

Regards,
Helen

[al olson]

Some thoughts on the history of ASA and ISO.

As I mentioned in an earlier post, they are each determined in a different manner but from the same gamma curve. Oren Grad cites 1983 based on his archive of Popular Photographies and I believe that would be correct. I have a copy of KODAK Films Color & Black-and-white, AF-1, published in 1978 that still uses ASA for the exposure standards of their films so the change-over would be later than that date.

Although the International Standards Organization was formed much earlier, the American National Standards Institute was slow to adopt the international standards in photography, computer languages, computer cabling, etc.

I believe the Europeans were earlier in using the ISO method to determine speed. They were already using the same method to determine the DIN. I seem to recall that some of the imported films (like Agfa and maybe Ilford) were already using ISO for awhile before Kodak changed over from ASA.

To obtain a standard film speed, either ASA or ISO, the film was exposed according to the standard and received standard development. The film manufacturers were usually free to specify the developer they used for standard development. Kodak usually used D-76 and Ilford standardized on ID-11 for the black and white films.

Now! I don't understand the confusion over Exposure Index. If the ISO is 400 and you rate the film at 400, then 400 is also the EI. If, instead you rate the film at 320, then the EI is 320, but the ISO is still 400.

Kodak does not always rate a film with an ASA or ISO. High Speed Infrared is a good example. In my 1978 Kodak Films book, Kodak gives "film speeds" under various filtering conditions, but does not call them ASA. This is true also today, and they are still not referred to as ISO.

To quote 1978 Kodak:
It's not possible to give exact speeds for Kodak High Speed Infrared Film, because the ratio of infrared to visible light is variable, ... Similar levels of visible light may be vastly different in the amounts of infrared radiation they contain. Make trial exposures to determine the proper exposure for the conditions under which you take your pictures. [The table that follows provides "Film Speeds" for various filters and light conditions.]

Their current WEB site states it slightly differently:
You cannot make exact meter readings to determine exposure for infrared films. Exposure meters are not calibrated for infrared radiation, and the ratio of infrared to visible radiation varies with the light source. Make trial or bracketing exposures over a five-stop range to determine the proper exposure for your application. Under average conditions, use the following speed ratings to make starting-point exposures with handheld meters or through-the-lens light meters. ...

In actuality, High Speed Infrared will provide satisfactory images using EIs ranging from 50 to 400 before correction for the filter factor, although Kodak recommends a daylight speed of 80 with no filter.

It is clear to me that if Kodak cannot rate a film to a standard, then they recommend film speeds, or exposure indices, as a starting point and expect the consumer to bracket to determine the results.

Cheers,
al

[al olson]

An addendum:

I have just reviewed a couple of Kodak Data Books titled Kodak Films for Black-and-white Photography. One, the 6th edition, was published in 1954 and the 7th edition was published in 1956.

For none of the film data in these Data Books is the film speed referred to as ASA. Kodak does call it an "Exposure Index" with the following caveat:

These settings are recommended for meters marked for American Standard Exposure Indexes. Normally they provide a safety factor in exposure when the film is developed as recommended.

Even more interesting is the data sheet on Royal-X Pan:

Exposure Meter Use: An index of 1600 should be used with most exposure meters for most applications of this film. This index makes the best possible use of the film's speed, graininess, and definition characteristics. It leads to minimum exposures which, with the recommmended normal development, yield good quality negatives for subjects of average brightness scale. For very flatly lighted subject, good negatives can often be obtained at two or three times this index value, using extended development.

In the next paragraph, Kodak states:

The American Standard Exposure Index is 650. This value is comparable to the daylight indexes published for other Kodak films and includes a safety factor which sets the exposure level substantially above the minimum required.


Hope this is helpful.
al

[Jonathan Brewer]

Good morning...............

................Let's clear up one thing and this is the last thing I have to say to Helen Bach, my suggestion about the 'short ends' was intended for anyone who hasn't dealt with the project, I figured you being a DP, you'd know that without me saying that, I'm sure you're a fine DP, I took you for your word that you've been one since the 1970's, and have never disputed that premise, you keep wanting to make this personal and it's not.

The statement about the folks who I had the privilege of watching/working with, knowing their 'shit' was a fact, they did know their 'shit' and I wanted to express that admiration for them here, my respect for them has nothing to do with you, it wasn't a putdown of you, you keep seeing attacks that aren't there, so by all means, just go away.

Tim..........................The first sentence I copied and pasted from the Kodak, refers to a determination of 'film speed', a number, and then they discuss why the labels, EI/ASA/ISO, the go into the consideration for why a EI designation versus an ISO number, push processing, different soups, testing, the fact that some consumers don't test, the way the film is used, and so forth, regardless......................you get a film speed that works, the labels are interchangeable and are thus meaningless in terms of real world Cinematography.

You say this.......................................'there is no standard for Determination of ISO speed for Motion Picture Films - ergo Kodak cannot be using the ISO Standard for determining the speed of motion picture film....

So however it is they may be determining and describing the "speed" of motion picture film, it isn't by using ISO'.............................................................

..........................and particularly this part of the above quote........................it .................'isn't by using ISO'......................................I don't believe, oh of course the ISO folks say it, .............but Kodak manufactures the film, they're the same folks who give some of their products an ISO number,.........they can do that, but can't use the same methods to come up with a reliable film speed when it comes to MP color negative film?????? That's what they say they can do, and I believe them, and if that's true the numbers are equivalent, and if they're reliable film speeds that work, then saying there is no ISO standard for MP color negative film is meaningless.

There's been a suggestion that there is no standard for MPCN because everybody tests, that's not true, some test, some don't, I've seen that with my own eyes, some test to confirm their own films speeds, some accept Kodaks number as true speed and start shooting.

How many week long discussions have folks had here about the zone system, busting out with step wedges, and densitometers, and calibrations, for films THAT DO have a number on the box that supposedly does reflect an ISO standard???? Testing is done regardless of whether or not there is or isn't an ISO standard for a particular emulsion, so ultimately, it means nothing,........................................Kodak, or whoever manufactures the film, gives out an EI-ASA-ISO, the number counts, you either consider this number as the true film speed, the way Kodak or whoever says it should be exposed and processed, or you test to confirm a new number in conjunction with how you're going to expose and process the film, if that's different from the manufacturers recommendations.


I don't care what the foodtaster says went into a meal, I believe the cook......
....................That's all I have to say.