ISO in the 1880's

[Greg Miller]

Does anyone know the approximate highest ISO that would have been available for Orthochromatic film and also glass plate in the 1880's?

Thanks.

[Walter Calahan]

Very very very low.

[jnantz]

maybe 1 ...

[dwross]

Yes, the old emulsions were/are slow by modern standards, but the story is more complex than a seemingly objective quantification would suggest.

In the first few years of the 1880s, plate manufacturing facilities sprang up everywhere and competition was fierce. Consumers reasonably looked for a way to easily evaluate the various brands. Manufacturers responded by slapping ‘sensitivity numbers’ on their boxes – numbers that didn’t reflect the subjective nature of photographic conditions. One famous story from the time has that when a certain plate company was upstaged in speed by a rival, they ‘solved’ the problem by reprinting their boxes with a higher number!

The problem with subjective numbers is tied to the nature of color-blind and ortho emulsions. They are basically only UV-sensitive. Because of this, emulsion speed is influenced by time of day, time of year, elevation, amount of cloud cover, and even the predominant colors of the scene being photographed. Different emulsions responded differently to different conditions, rendering the sensitivity ratings of the plates largely meaningless.

In the 1912 edition of Dictionary of Photography, E.J. Wall wrote, “If only all plate makers would also adopt a standard colour test, and give the relative sensitiveness of their plates to, say, four standard universal colours of known luminosity, such information would gradually become almost as greatly appreciated as the speed numbers themselves.”p.628. This advice was even more pertinent 30 years earlier.

In addition, the 1880s saw great advances in developer research, particularly the addition of sodium sulphite to pyro formulations and the discovery of organic developer ingredients such as metol, amidol, and glycin.

Along with the modern rediscovery of the old recipes must go a rediscovery of the old ways of evaluating the materials. Besides being just plain practical, it’s a great deal of the fun.

[eddie]

thanks dwross. great info.

i will say this. i have been using wet plate collodion for seeral months now. i am in NY. my most recent exposures have been 1 sec at f4 in "direct" overcast sun, 2-5 sec in open shade on the north side of a building and up to 1 sec. at f16 in direct sun.

it is blue sensitive so i make my exposures by trail and error...i am pretty good at getting fairly close now.

hope this helps.

eddie

[dwross]

Eddie,

Yes, I agree completely with your approach. I think it's very satisfying to return to an 'experience-based' photography. I think that people are starting to realize how much is lost when we become totally disconnected from the technology we use. I'll probably never be able to 'tinker' with the engine of my hybrid car in my driveway, but I am able to understand my photographic tools and materials.

d

[Andy Eads]

Reverse calculating using the sunny 16 rule, Eddie's info indicates he is getting an ISO equivalent of 1/16.

[Vaughn]

Reverse calculating using the sunny 16 rule, Eddie's info indicates he is getting an ISO equivalent of 1/16.

Wouldn't that be ASA 1 in the direct sun? Vaughn

[goamules]

I also shoot wetplate, and I also can guesstimate an exposure pretty well now, just looking at the brightness of the ground glass.

But the inventors of dryplates were seeking more than just something easier to use. It was a race for speed. I believe collodion is about an ISO 1, and dryplates were around ISO 25 or faster.

I think as photography got to this technology and these speeds, guessing exposures became more error prone. With wetplate, I can shoot, develop, and know my exposure was wrong in 5 minutes. Then I adjust and shoot another. When photographers began to take the plates home to develop later, it was much more important to have consistant ISO and perhaps some technological light measureing method. I wonder when light meters arrived?

[Gene McCluney]

Until the advent of Panchromatic plates and films, which is later than the materials in this discussion, photographers developed by inspection, thus were able to compensate to some degree for exposure variations.

[Bill_1856]

Around the nineteen tens, the first meaningful "exposure index" were given to motion picture film (as one would expect, considering the money imvolved), but even then exposure was usually determined by shooting a short strip of film with varying exposures to pinpoint the correct one (I'm not sure when the first selenium light meters appeared). Orthochromatic film had a modern ISO equivilant of about four (4). By the '20s it had risen to ten (10), with panchromatic film about half that.

[Sevo]

Until the advent of Panchromatic plates and films, which is later than the materials in this discussion, photographers developed by inspection, thus were able to compensate to some degree for exposure variations.

With the rather massive deviations within a single pack of plates at that time, no exposure meters, and having no shutters to speak of while exposure times already were scratiching at the second mark, that compensation often went way beyond reasonable contrast levels either way. In the past I have printed large amounts of old negatives from all ages for a museum customer of mine, and the exposure of early dry plates positively was the worst of them all.

Sevo

[jnantz]

Wouldn't that be ASA 1 in the direct sun? Vaughn

yup ...