Emulsion Speed in history

[Oren Grad]

Thanks, I could not find that in the datasheet on the Kodak site.

Publication F-4016, "KODAK PROFESSIONAL T-MAX Films", contains the following on p. 19:

The nominal speed is EI 1000 when the film is processed in KODAK PROFESSIONAL T-MAX Developer or KODAK PROFESSIONAL T-MAX RS Developer and Replenisher, or EI 800 when it is processed in other Kodak black-and-white developers. It was determined in a manner published in ISO standards.

 

[Tim Gray]

Thanks, I could not find that in the datasheet on the Kodak site.

I found this quote on page 19 of f4016 (2007 version - might be the same as the one on the website now):
"The nominal speed is EI1000 when the film is processed in KODAK PROFESSIONAL T-MAX Developer or KODAK PROFESSIONAL T-MAX RS Developer and Replenisher, or EI800 when it is processed in other Kodak black-and-white developers. It was determined in a manner published in ISO standards. For ease in calculating exposure and for consistency with the commonly used scale of film-speed numbers, the nominal speed has been rounded to EI800. "

 

[ic-racer]

Publication F-4016, "KODAK PROFESSIONAL T-MAX Films", contains the following on p. 19:

The nominal speed is EI 1000 when the film is processed in KODAK PROFESSIONAL T-MAX Developer or KODAK PROFESSIONAL T-MAX RS Developer and Replenisher, or EI 800 when it is processed in other Kodak black-and-white developers. It was determined in a manner published in ISO standards.

I missed that. I think the reason they don't give the ISO is that there can only be ONE ISO for the film, whereas they want to point out out some exposure index increase with T-max developer (which I have noticed also).

Kodak tries to explain why they don't publish the ISO here http://www.kodak.com/global/en/professional/support/techPubs/cis185/cis185.jhtml but in reality they are 'hiding' the ISO from the consumer (its not like they didn't do the tests).

 

[Photo Engineer]

There is a specific scientific reason why two developers can give ISO or EI or ASA or whatever, values that are a stop to 2 stops apart. It has to do with the toe of each component in a film. A sharp toe, induced by a developer will raise speed by a stop or more, but a soft toe will decrease speed relative to an intermediate position.

This is common in film and paper and is an arguing point in the ISO standards committee. Now, if you want me to draw the curves to prove it, I wil or you can take my word but I guarantee you that if I draw the curves it will put this to rests and leave some people with egg on their face.

Believe me, I have done the experiments to prove this more than one time. I should add that grain and sharpness will probably change.

PE

 

[AgX]

That was the reason that the early forms of DIN standards specified that all films were to be tested by means of one special standardized developer under standardized circumstances. However these seemed off the practical use.

 

[Photo Engineer]

Kodak uses 1 standard developer for release tests of all B&W film. It used to be D-76.

PE

 

[ic-racer]

There is a specific scientific reason why two developers can give ISO or EI or ASA or whatever, values that are a stop to 2 stops apart. It has to do with the toe of each component in a film. A sharp toe, induced by a developer will raise speed by a stop or more, but a soft toe will decrease speed relative to an intermediate position.

This is common in film and paper and is an arguing point in the ISO standards committee. Now, if you want me to draw the curves to prove it, I wil or you can take my word but I guarantee you that if I draw the curves it will put this to rests and leave some people with egg on their face.

Believe me, I have done the experiments to prove this more than one time. I should add that grain and sharpness will probably change.

PE

Here is one of the biggest differences I have personally seen: T-max developer vs dilute Rodinal.

BTW does anyone have a link to the ISO standard? Every time I search I get sites that want to charge for it.

 

[Photo Engineer]

Your graph shows exactly my point. Look in the toe. The sharper toe gives longer straight line latitude and higher speed. The inflection point of the toe is almost exactly the same. With enough data down in that region it would be a bit more clear. Thanks for the post.

PE

 

[R W Penn]

In the 1950 I used Ansco Super Pan Press ASA125 for nite football games and #22 ? flash bulb. It was size of a 60 or 100 watt lite bulb. Press 25 and #5 peanut bulbs where too weak. Super XX was asa 100

 

[domaz]

Any film emulsion when coated on paper support, will give at least 1 stop in speed from back reflection and another stop from the high coated silver level. In actuality, the 3000 speed film was about 800. Kodak had a 3000 speed instant product ready to go when they lost the lawsuit to Polaroid and it was never introduced.

This is interested so if someone released a film coated on paper it could be very fast and possibly still scannable? Or is film coated on paper support basically useless for enlargement/scanning purposes?

It would be nice to have a high speed film that could beat the pants off the high-noise digital low-light shots.

 

[Photo Engineer]

Yes, a film emulsion would about double in speed, but scanning shows the paper fibres and so it would be necessary to either use RC or a heavy baryta paper. Even there, the baryta would show some graniness due to the baryta. I have posted samples of various hand coated papers here. You can clearly see the fibre grains.

Also, film emulsions on paper support have to be slightly modified due to the addenda in the paper itself.

PE