Which of the inventors associated with photography do you think had the largest impact on photography?

Answer 1

Camille and Henri Dreyfus.

The Dreyfus brothers invented cellulose acetate, and to understand why it's important you need to know how camera emulsions used to be made in the really old days.

The first really usable camera emulsion was the Daguerreotype. It was developed in heated Mercury. Then came the tintype which was developed in potassium cyanide, and probably a few other processes that'd kill ya quick. Worse: you can't reproduce any of these photos like you can with a negative or a digital file because they were created on metal plates.

Next was the wet collodion process, which was coated on a glass plate. You had to make the emulsion, coat it onto the plate, take the picture and develop it before the collodion dried...add to that the minor problem that collodion is guncotton dissolved in ether, hence extremely flammable.

Then someone figured out Gelatin could be used to coat plates, and the dry plate was invented. This solved the problem of having to haul a darkroom into the field (which they had to do during the Civil War) and it greatly cut down on the number of photographers that were killed by their work, but you still had to use a big camera to hold the plates, you still had to haul around lots of weight, and you still had to reload the camera after every shot. Dry plates survived for a very long time: pro astronomers used plates because plates don't sag when you lay them flat and they don't expand and contract with temperature changes. Astrophotography has gone digital for two reasons: it's easier to work with digital files than plates, and Kodak no longer makes plates.

Next came George Eastman's paper negative film. It's flexible so you can make a roll of film out of it. To use it you had to strip the emulsion off the backing film - not an easy task to do, but an extremely easy task to screw up.

Then came nitrate negatives. You can make a clear film by dissolving guncotton. This gives a usable negative you can print with an enlarger, but also one that is extremely flammable.

And finally came cellulose acetate. It's transparent. It's flexible. And it's not flammable. Photography became truly popular only when it was safe and easy, which Kodak Safety Film enabled.