Let’s Talk Photography Ep.62 – A Potted History of Recording Light

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Bart Busschots (host) – @bbusschots – Flickr

In this solo show Bart takes you on a journey from photography’s pre-history right through to the digital age. Photography may have been announced to the world in 1839, but it took a lot of work by a lot of people to get to that point, and of course, a lot of work to get from there to our modern smartphone cameras!

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Show Notes

The traditional, simplistic, timeline of Photography starts in 1839 when Louis Daguerre announces the first photographic process (which he humbly calls after himself; the daguerreotype). This implies there was no photography in 1838, and then it’s born whole in 1839.
In reality the discoveries that made it possible, and the invention of photography itself was a slow process happening in parallel all around the world, and there was no one moment when the world went from not having photography to having it.
Reminder — a camera is a device which uses a lens to project an image onto a photo-sensitive surface where that image is then captured.
Today, almost all photographic images are captured electronically, but right up until the end of the 20th century, photography was all about chemistry — using light-sensitive chemical compounds and a whole bunch of additional chemistry to permanently record the projected images.
We figured out how to project images centuries before we figured out how to record them, so we’ll be ignoring that part of the puzzle in this episode (see Camera obscura — en.wikipedia.org/… for more)
To get to Daguerre there are three problems that need to be solved
1. a chemical reaction that’s affected by light intensity (i.e. some chemistry that varies with the level of illumination)
2. some way to make the chemistry visible as an image humans can view (i.e. a development process)
3. some way to apply the brakes and stop light from continuing to affect the recorded image (i.e. some form of fixer)

The beginning

As early as 1717 Johann Heinrich Schulze was making temporary images by placing stencils over bottles containing a mixture of chalk (_CaCO3) and silver nitrate (AgNO₃) in nitric acid (HNO₃). The image was utterly fleeting, but you could see that the chemical in the bottle behaved differently in the places where the light hit it and where it did not. Not a recording, but an early hint that at least some salts of silver were photo-reactive.
By around 1800 Thomas Wedgwood, son of the English industrialist and pottery genius Josiah Wedgwood has taken things a little further. Wedgwood was able to coat surfaces in photo-reactive chemicals rather than using bottles of liquid. He also captured projected images, so his device could be described as a camera. Unfortunately his camera only managed to record crude silhouettes, and only temporarily. He couldn’t figure out how to fix his recorded images (make them permanent).
In 1816 Joseph Nicéphore Niépce took things a little further when he was able to use paper coated with silver chloride (AgCl) to capture images with gradations of light and dark. Unfortunately he also couldn’t make them permanent, so these early photographs had to be stored in the dark, and each time you took them out to view them they degraded a little bit more!
By 1822 Niépce had abandoned silver halides (a group of chemicals that includes silver chloride) altogether, and succeeded in capturing permanent images on sheets of metal or glass coated in bitumen of Judea, AKA Syrian asphalt. At this stage he was not capturing images, but making contact-prints by placing his coated sheets of metal or glass against the thing to be copied and then leaving the sandwich out in the sun to expose. The reason he had to resort to contact prints is that his chemical coating was not very light-sensitive at all!
- This process relied on the fact that exposure to light made the bitumen hard. The more light, the harder the bitumen. If you coat a surface with the stuff, expose it to light for a while, and then wash the surface with a solvent, the parts that got no light will wash away completely, the parts that got some light will wash away a little, and the parts that were well lit will not wash away. Once you stopped washing, the bitumen stopped being removed, so the images created were permanent.
- The big drawback is how slowly the hardening happened, resulting in exposure times measured in hours or maybe even days!
Niépce kept at it though, and by all accounts he managed to make his first permanent record of an image projected onto a coated surface by a lens in 1824. In other words, Niépce invented the first working camera in the early 1820s, almost two decades before Daguerre.
- The first captured image was destroyed during later experiments.
- The oldest known surviving photograph in the world was created by Niépce in either 1826 or 1827. It’s an image of a city-scape (View from the Window at Le Gras — en.wikipedia.org/…), and while we’re not sure exactly how long he exposed it for, the absolute minimum plausible estimate is 8 hours, and it was probably a lot more than that, possibly even multiple days!
- In Brazil, in the early 1830s Hércules Florence was also working with salts of silver (), and he was able to use them to produce permanent images.
  - Florence did not publish or share his work, so he didn’t contribute to science as such
  - The oldest surviving image he created was taken in 1833. It’s an image of some chemical flasks he titled ‘Epréuve Nº2 (photographie)’ (implying there was probably an even earlier image)
- Meanwhile, in England, Henry Fox Talbot was also experimenting with silver salts (silver chloride to be precise)
  - In 1835 Fox Talbot produced durable negative images on paper that he then contact-printed from to produce a final positive image.
  - This concept of producing a negative that then gets printed again to produce the final image becomes the norm in photography.
  - There is no reason the same negative can’t be printed many times to produce many positive images
  - Because Fox Talbot’s negatives were on waxed paper, they were not particularly transparent, and the fibres of the paper limited the amount of detail he could capture in his final images.
- In France, Louis Daguerre has been perfecting the photographic process he would reveal to the world in 1839 as the daguerreotype (he had partnered with Niépce in the 1820s, and continued his work after Niépce died in 1833)
  - Daguerre’s process started with polished sheets of silver-plated copper. These plates were made light-sensitive by exposing them to iodine vapour which produced silver iodide (AgI) on the surface. The plate was then exposed in a camera, and the image was revealed (developed) and fixed by exposing it to mercury vapour and then washing it to remove any lingering silver iodide.
  - Initial exposure times were of the order of minutes, but soon reduced to tens of seconds.
  - This is a direct positive process — the metal plate exposed in the camera becomes the final image.
  - Very detailed with a theoretical resolution of the size of a single silver iodide molecule!
  - Not reproducible! (think very old Polariods)
- Also in 1839, Fox Talbot goes public with his process which he calls photogenic drawing. As well as being much less detailed, Talbot’s exposure times were much longer than Daguerre’s.
- Finally, in 1841 Fox Talbot announces an improved version of his process that he names the calotype (AKA the Talbotype) which has much shorter exposure times

Having Your Cake & Eating It

All the ingredients for modern photography were there by 1839, but no one process could give you everything you wanted (pick 2!):
- short exposure time
- highly detailed images
- infinitely reproducible
The next big step was to replace Fox Talbot’s waxed paper with glass. This happened in 1851 when Frederick Scott Archer and Gustave Le Gray simultaneously but independently developed the so-called wet plate collodion process
- This involved coating a sheet of glass with a cocktail of chemicals including silver halides, exposing it to light, and then developing it, all before the emulsion dried, so within about 15 minutes (This meant portable darkrooms when working outside the studio).
- This results in infinitely reproducible images that were highly detailed with exposure times on the order of seconds
Direct positive imaging did not go away though, two new variants of it were invented that used similar chemistry to the collodion process — Ambrotypes and Tintypes. These were basically more modern Daguerreotypes. They existed simply because they were cheap!
So everything’s perfect now? Nope! Some big problems remained
- Needing a portable light room is very impractical!
- Prints were the same size as negatives, so if you wanted a big print, you needed a big sheet of glass in a big camera!
- The sensitivity of collodion emulsions varied depending on the colour of the light. If you exposed for the blue sky the green landscape would be under exposed, and vica-versa (not panchromatic)
- All commonly available processes are black and white (there is some very early and very experimental work on colour photography going on already though)

Going Portable

In 1871 Richard Maddox removed the need for a portable darkroom when he invented a gelatine-based emulsion that could be layered on glass that would keep indefinitely, producing so-called dry glass plate photography.
Dry glass plates were still bulky and brittle though, so the next big leap forward came around 1887 to 1888 when multiple dry glass plate manufacturers, including Eastman Kodak, hit on the idea of using celluloid instead of glass to produce photographic film.
Gelatin proved to be the answer to another problem too, the need for negatives to be the same size as the desired final print. By the late 1880s gelatine-based photographic paper that was sensitive enough to be used with an enlarger was commonly available.
The first commercially available panchromatic photographic film hit the market in 1906.
Over time the highly flammable celluloid was replaced first with acetate and later with polyester
The combination of small flexible film with photographic enlargement made the small portable cameras possible, and lead to the boom in photography in the 20th century and beyond.

Adding in the Colour

The first commercially successful colour photographic system was Autochrome, released by Kodak in 1907.
- This was an additive colour process
- Used glass plates, not film!
The first commercially successful colour film didn’t hit the market until Kodak introduced Kodachrome in 1935 (just a little under a century after Daguerre introduced the world to photography)
Surprisingly, there is a long history of experimental colour photography going all the way back to 1848!
- The first known colour photograph was produced by Edmond Becquerel in 1848. They had only a tiny hint of colour, and the process was utterly impractical.
- James Clerk Maxwell demonstrated a process for producing additive colour images in 1861. The process involved taking three photographs of the same subject with red, green, and blue filters, and then projecting them onto a screen using the same filters.
- Louis Ducos du Hauron patented a process for printing subtractive colour images in 1868. It was utterly impractical though.
- Gabriel Lippmann published a process for creating colour images in 1891, and it earned him the 1908 Nobel prize for physics. His process was very complex and produced plates that had to be back-lit to be viewed, so prints were impossible.

One Last Hurrah for the Direct Positive Image

The so-called Instant Camera was an interesting throwback to older direct-positive processes like the Daguerrotype, Ambrotype & tintype
The first instant film was developed by Edward H. Land in 1947. It was monochrome and had a sepia tone.
The Polaroid 95, the first instant camera, was released in 1948
In 1963 Polaroid introduced Polacolor, the first instant colour system

Going Digital

The first digital image sensor was invented by Peter Noble in 1967, it had a whopping 100 pixels in total (a 10×10 grid)
By 1972 Noble had managed to get to a 64×64 sensor
In 1973 Fairchild Semiconductor released a 100×100 pixel CCD chip
In 1975 Kodak invent the bayer filter for creating colour CCD images
In 1986 Kodak created the first megapixel sensor
Adobe released the first version of Photoshop in 1990
Between 1993 and 1995 NASA’s JPL develops CMOS sensor
In 1995 Kodak and Apple release the first digital cameras marketed at consumers
In 1996 Kodak, FujiFilm, AgfaPhoto, and Konica introduce the Advanced Photo System, AKA APS

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