Forum Übersicht - RE: ASA- und DIN-Standards vor 1960: Änderung der Norm - 2

Hi,

möchte an dieser Stelle für Leute mit alten Archivbeständen kurz darauf hinweisen, dass vor 1952 bis ca. 1960 noch Nitratfilm im Umlauf war.
Diese Filme hatten keine Acetat bzw. Kunststoffschicht als Träger, sondern Trägermaterial aus Nitrocellulose.

http://www.klauskramer.de/nitrofilm/nitrat..._top_04-09.html
QUOTE ... Film- und Fotoarchive sind jedoch nicht allein durch die leichte Entzündbarkeit des Nitratmaterials gefährdet. Nitratfilme zersetzen sich selbst. Die hierbei frei werdenden säurehaltigen Gase schädigen in der Nähe aufbewahrtes Archivgut...[/quote]


Nur so nebenbei.
Wilma

ZITAt (Stuessi @ 2011-07-18, 21:24) Welche Filme sollen davon betroffen gewesen sei?[/quote]
Wenn ich das so genau wüßte... ;-) 1960 war ich noch flüssig, insofern kann ich da Nichts aus erster Hand zu beitragen. Bei meinen Netzrecherchen habe ich verschiedene Filme, auf die das zutraf, konkret erwähnt gefunden, habe mir diese aber nicht gemerkt. Ich werde aber in Zukunft besser darauf achten und dann hier davon berichten, da ich selbst nicht den Hintergrund verstehe, warum das in vielen Fällen so gewesen sein soll, aber nicht in allen (und wo man da die Grenze ziehen kann).
Sicherlich kann man das klären, wenn man die in den verschiedenen Normen beschriebenen Verfahren studiert, aber dafür müßte man diese erstmal vorliegen haben - so weit bin ich aber selbst auch noch nicht. Mit fünfzig Jahren Abstand ist es schon schwierig, überhaupt herauszubekommen, welche Standards und Normen genau damals in welchen Ländern galten. Da habe ich zwar schon einige Puzzleteile zusammengesetzt, aber auch noch kein Komplettbild. Gemeinsam geht das mit Sicherheit einfacher, insbesondere, wo wir hier im Forum auch Mitglieder haben, die die Entwicklung damals selbst erlebt haben und möglicherweise sogar noch Dokumente aus dieser Zeit vorliegen haben.

Viele Grüße,

Matthias

ZITAt (Stuessi @ 2011-06-21, 13:08) Es hat nur eine Umstellung in den 50-er Jahren gegeben: aus 18/10° DIN wurde 1957 18 DIN[/quote]
Eine kleine Ergänzung: Mit der DIN 4512:1957 wurde aus der Zehntelgrad-Bruchschreibweise 18/10° DIN zunächst 18° DIN, erst mit der Revision DIN 4512:1961 fiel dann auch das Gradzeichen weg: 18 DIN.

In der ISO-Norm (z.B. ISO 5800:1979 und später) wird das Gradzeichen für den logarithmischen ISO-Wert (der den DIN-Graden und den 1960 eingeführten logarithmischen ASA-Graden entspricht) hingegen bis heute weiterverwendet: ISO 100/21° = ISO 100 = ISO 21° = 100 ASA = 21° ASA = 21 DIN.

Viele Grüße,

Matthias

ZITAt (Stuessi @ 2011-07-18, 21:24) Welche Filme sollen davon betroffen gewesen sei?[/quote]

Ein paar Beispiele:

Ilford HPS:

1958-1960: ISO 400/27° (keine Änderung der Emulsion 1960)
1960-1998: ISO 800/30°
Quelle: http://en.wikipedia.org/wiki/Ilford_HP

Ilford HP3:

1941-1952: ISO 125/22° (tatsächlicher Emulsionswechsel 1952)
1952-1960: ISO 200/24° (keine Änderung der Emulsion 1960)
1960-1969: ISO 400/27°

Ilford FP3:
1942-1951: FP3 40/17° (tatsächlicher Emulsionswechsel 1951)
1951-1960: FP3 64/19° (keine Änderung der Emulsion 1960)
1960-1968: FP3 125/22°

http://en.wikipedia.org/wiki/Ilford_HP
ZITATHP3 went through two speed changes in its history, but only one actual change to the emulsion. In 1960 the 200 ASA emulsion was relabelled to 400 ASA with no change to the product. The 200 ASA speed included an exposure safety margin, but with improvements in light meters this was deemed unnecessary. Thus the speed was revised up to 400 ASA.[/quote]
http://en.wikipedia.org/wiki/Ilford_FP

http://www.ureader.de/msg/15718923.aspx
ZITAT1960:

Ilford HPS 27° DIN
Ilford HP3 24° DIN
Ilford FP3 19° DIN

Neue ASA-Norm zur Filmempfindlichkeit (Norm PH 2.5 1960): 200 neue ASA
entsprechen 100 alten ASA, 21 DIN entsprechen somit 200 ASA.

Es gibt eine zweite, logarithmische ASA-Reihe: Vermehrung um 1 gleich
Verdoppelung der Empfindlichkeit, wie bei deutschen Lichtwertzahlen
(später auch laut DIN als Belichtungswert bezeichnet). Logarithmische
ASA-Reihe verwendet Grad-Zeichen. 5 Grad ASA gleich 21 DIN. Fomag
spekuliert, daß sich diese ASA-Reihe als international einheitliche
Kennzeichnung von Filmempfindlichkeiten durchsetzen werde, zumindest im
westlichen Wirtschaftsraum. Halbe Stufen sind vorgesehen, Drittelstufen
nicht, was die amerikanische Skala etwas gröber macht als die deutsche.

Kodak verwendet auf Filmschachtel die neue, logarithmische ASA-Reihe.
FoMag vermutet, daß auch in Deutschland die DIN-Empfindlichkeitsangabe
um eine Stufe angehoben wird.
[...]
1961:

Neufassung der DIN 4512, Blatt 1:

-Anpassung an ASA PH 2.5 1960, heutige Entsprechung logarithmische DIN-a
rithmetische ASA beginnt (12 ASA=12 DIN, 100 ASA = 21 DIN, 800 ASA = 30
DIN)

-Teststreifen werden auf Gamma etwa 0,6 entwickelt, nochmals milder
arbeitender Entwickler wird verwendet.

-Gradzeichen verschwindet (also 17 DIN statt 17 Grad DIN)

-Bei unveränderten Filmen wird die Empfindlichkeitseinstufung in den
meisten Fällen verdoppelt. (Wer mit seinen Filmen eingearbeitet ist
braucht sich um dat neumodische Tüddelkroams also nicht zu kümmern)

-das neue Normblatt gilt nur für SW-Negativfilme.

-Wirklich verändert wurde die densitometrische Auswertung der Testfilme.
Die alte Methode ergab für die praktische Anwendung eine Überbelichtung
von gut einer Blende und damit unnötig dichte Negative. Dies hielt man
seinerzeit für wünschenswert (Anmerkung von rck: Die Scheiner-Rekorde
führten zu praktisch viel zu dünnen Negativen. Offenbar wollte man mit
den DIN-Festlegungen diesbezüglich auf der sicheren Seite sein.)

Zwischenzeitlich hatten die Hersteller ihre Empfindlichkeitswerte nach
DIN auf die Schachteln gedruckt und dann im Beiblatt empfohlen, den
Belichtungsmesser entsprechend der tatsächlichen Empfindlichkeit höher
einzustellen. Der Verbraucher reagierte verwirrt.
[...]
1962:

Ilford FP3: 22° DIN
Ilford HP3: 27° DIN
[...]
DIN folgte vor einem Jahr ASA bei Anhebung der Empfindlichkeit um eine
Stufe, wird aber nicht von allen Herstellern gleichzeitig umgesetzt.
Daher immer noch Filme mit unterschiedlichen Angaben im Markt. Adox'
Lösung: Gar keine Empfindlichkeitsangabe auf der Packung mehr. Im
Beipackzettel der Hinweis, bei R/KB 14 den Beli auf 17 Grad DIN
einzustellen, bei R/KB 17 auf 21 Grad DIN, bei R/KB 21 auf 24 Grad DIN
und bei R/KB 27 auf mindestens 27 Grad DIN. 30 Grad DIN zu erreichen bei
Entwicklung in Adox E24, Atomal neu oder Ultrafin.[/quote]
NB Zum besseren Verständnis: Bei den erwähnten logarithmischen ASA-Graden handelt es sich um den Empfindlichkeitsleitwert Sv des APEX-Systems.

http://www.photomemorabilia.co.uk/Ilford/Chronology.html
ZITATFilm Speed Changes:

At several points in the chronology (below) reference is made to black & white film speeds changing (doubling) in 1960. This arose when American Standard PH2.5-1960 made a change to the previous American Standards Association (ASA) method of speed rating black & white film emulsions by removing an exposure safety factor that had previously been applied. The result was an apparent doubling of flim speeds.

With the greater use, by 1960, of colour films that needed accurate exposure measurement, and therefore greater use of accurate exposure metering systems, the ASA decided there was no longer need for black & white emulsions to retain their previous exposure safety margin.

This link gives access to a short article entitled "The Jump in Film Speeds", by Andrew Matheson. It is extracted from 'PhotoGuide Magazine', Vol.11, No.8, August 1960, pages 662-665.

A similar speed change, leading to a doubling of black & white film speeds (no change to the actual emulsions) was anticipated in the UK and indeed, the new, increased, film speeds appeared on film packaging during 1960, leading to confusion by some amateurs, especially since flash exposures were advised to best still be based on the lower (old) film speed rating (ref: Amateur Photographer 'Readers Ask', 11th Jan.1961). However, the new British Standard that would formally ratify this doubling of film speed was said to still be "expected almost daily" in Amateur Photographer magazine's editorial paragraphs (page 943) as late as 21st June 1961. In fact, AP may have had to wait longer than they anticipated, since the relevant BS 1380 didn't finally arrive until 1963.

The change did NOT apply to colour films, neither negative nor transparency (reversal) films, where no exposure safety margin had ever been incorporated into their speed rating. Colour film always give best results when exposed accurately to the true emulsion speed.[/quote]
http://www.photomemorabilia.co.uk/Ilford/F...peeds_1960.html
ZITATThe Jump in Film Speeds

Article by Andrew Matheson in August 1960 PhotoGuide Magazine

THE JUMP IN FILM SPEEDS
Film speeds have a habit of changing when no one is looking. Here are the facts behind the recent ASA speed changes.
By ANDREW MATHESON, London

OUT of the blue, American film makers have doubled recommended emulsion speeds. What made them do it-and why didn't they do it before?
Speed is one of the most important film characteristics. Measuring it remained the biggest headache in the film industry for nearly half a century. Not because of a lack of methods, but through too many of them. It took nearly fifty years before someone hit on the idea of relating film speed to final print quality. One reason why it took so long was perhaps that it was a cumbersome way, outside and in the laboratory. But it brought order into a chaotic state of affairs. That was the beginning of the ASA (American Standard) exposure index numbers-and later the BS (British Standard) system.
For nearly thirteen years it worked like a charm. Photographers had a figure that they could set on exposure meters and use in exposure tables, and obtain correctly exposed negatives.
Last year the American Standards Association burst into this seemingly peaceful state of affairs. A new standard, made official a few months ago, in effect doubled all previous film speed ratings. At once we are at sixes and sevens again - or more precisely at sixes and dozens. What has happened?

MAXIMUM FILM SPEED
The ASA speed system worked like a charm - or nearly. In fact, some curious rumblings started up behind the scenes almost as soon as it appeared.
The first was the cult of maximum film speed. Some ten years ago clever photographers tried cooking a film in the developer for ten hours instead of ten minutes. They discovered that they got- in addition to a lot of fog- increased effective film speeds.

TEN TIMES INCREASE?
The actual speed gain was the source of many bitter arguments in clubs and photo journals, but seemed to range from a five to ten fold increase. Usually the eager darkroom beaver claimed that he took a film rated at 50 ASA, set his meter to 500 ASA, and exposed accordingly. After an overnight developing session, he proudly waved a strip of printable negatives. There was no cheating, but how did he do it?
Some of the speed gain was genuine - but not all tenfold of it. Finality development boosted the speed 2 to 21/2 times (even if it ruined the negatives in every other respect).
Certain subjects could stand reduced exposures by having restricted tones, giving another doubling of effective speed. And finally, ASA film speed indexes (pre-1960) are designed to yield 21/2 times over-exposed negatives as a safety factor against under-exposure. So 21/2 x 2 x 21/2 = 121/2. Yes, maximum film speed claims were genuine - but misleading.

MINIMUM CORRECT EXPOSURE
It is this last factor, the latitude or safety factor against under-exposure, which has now got shot down. Actually, it had been under fire for some while.
From time immemorial the average photographer's bogeyman used to be under-exposure. As new concepts of image quality such as acutance came on the scene, together with new types of ultra-speed films, it became apparent that over-exposure was just as bad. With the fastest films, it seems quite senseless to over-expose pictures by a safety factor if you wanted to make the most of the enhanced film speed. And such films, more than any others, appreciably suffered in quality even on comparatively slight over-exposure.
Film manufacturers and users soon found that they got noticeably better results by using an appreciably higher film speed figure on their exposure meters. Films began to have two speeds: the official one and a second figure for "minimum correct exposure". Some manufacturers went so far as to quote two sets of figures for every emulsion on these lines. And plenty of photographers found that by using the higher of the figures they got as good - if not better - negatives.

DOUBLE FOR BLACK-AND-WHITE
To deal with this new confusion, the ASA speed system has been revised. Under the new system, emulsion speeds of black-and-white negative films become double what they were before. That simple process virtually eliminates the previous safety factor or margin against under-exposure. The confusion has not yet departed; for some manufacturers immediately doubled their official film speeds, others still keep quoting old ASA values. And it is a little difficult to make up your mind just where you are if you don't know who has done what, and whether a published ASA figure is an old speed index or a new one. In addition, the British Standard (BS) speeds are still unchanged for the moment, though probably they will eventually fall in line with the new ASA range.
The speed revision also cleared up a few outstanding points. One was to simplify the laboratory side of testing film speeds, and to bring it into line with another widely used system, the DIN speed criterion. When originally introduced nearly thirty years ago, the latter was itself a little unrealistic, for it measured speed under laboratory conditions of development which no amateur would ever use. The DIN standard was revised in 1958 to remove this difficulty. The new ASA testing method is very similar to the new DIN procedure; only the figures are different. On the other hand, DIN film speeds still are not minimum-correct-exposure speeds: the two-fold safety factor remains.

HOW IT AFFECTS YOUR METER
The somewhat complicated situation then boils down to this. To determine correct exposures, especially with exposure meters - whether separate, built into the camera, coupled with aperture speed controls, or completely automatic - we need a film speed setting. Most modern exposure meters are calibrated in ASA and in DIN figures.
With a film rated in ASA, we have to find out first whether it is the old or the new ASA figure. If it is the old one, set the exposure meter to double that speed. If it is the new one, use it as it stands. If the film carries a DIN speed rating, set the exposure meter to double the given figure.

NO JUMP IN COLOUR
All this applies exclusively to black-and-white negative materials. It does not apply to colour films, because no colour film rating system - with or without safety factors - yet exists. Colour film speed is not an entity measured in the laboratory; it is a manufacturer's recommendation. By rating a film at, say, 32 ASA, the maker merely tells us that if we set our exposure meter to 32 ASA for that colour film, we shall get correctly exposed pictures. Colour film has very little latitude anyway; exposures must be correct and neither over nor under. So for colour shots the recommended exposure meter settings remain what they were before.
One practical effect is that black-and-white films suddenly appear to be very much faster again than colour films. In reality, neither type of film has changed at all.

UNIT VALUES
ASA figures are known as "arithmetic". That means that the speed figure or exposure index is directly proportional to the actual speed. A film of 200 ASA is twice as fast, and needs half as much exposure, as a film of 100 ASA.[/quote]
Demnach bezog sich die nominelle Empfindlichkeitsänderung auf alle Schwarzweiß-Negativfilme, nicht jedoch auf Farbnegativ- und Farbumkehrfilme. Das macht die Umrechnung nicht leichter...

Viele Grüße,

Matthias