1860

The wet plate, 1851–1880

The collodion process (Frederick Scott Archer, 1851) was the photography of our great-grandparents' generation. In the darkroom the photographer coated a plate with collodion, sensitized it in a bath of silver nitrate and put it in the camera while it was still wet. Straight after the exposure the plate was developed and fixed, and a few minutes later the portrait was finished. A tintype (ferrotype) is made on black-japanned iron, an ambrotype on glass with a black backing behind it.

Both are really thin negatives. The silver is light, so against the dark backing it reads as a positive. That is also why the pictures are reversed left to right, like a mirror image.

Why do red lips turn dark and blue eyes turn pale?

Collodion sees only violet and blue light, roughly 380 to 500 nm. Red, orange and yellow barely register. To the plate, red lips, rosy cheeks and freckles are almost black, skin looks darker than in life, and blue eyes and blue skies come out pale, almost white. That is why people in old portraits look sterner and more “weathered”.

Why sit still?

A plate was about ISO 1. In a studio lit by a skylight, an exposure took 3–15 seconds. The photographer took the cap off the lens and counted. An iron head brace stood behind the sitter. Anyone who moved stayed on the plate as a transparent ghost.

The Petzval lens

Joseph Petzval's portrait lens (1840) was about 20 times brighter than the first lenses. It is sharp in the middle and soft towards the edges, and the background “swirls” around the sitter. The edges of the plate are darker.

What this tool does

• It records every frame during the exposure and adds them up in linear light, as a plate does. Hand shake is aligned away; your own movement stays.
• It converts color using the measured spectral sensitivity of collodion (Skladnikiewitz, Hertel and Schmidt, 1998), not an ordinary black-and-white filter.
• It simulates the Petzval lens. An AI model running on your phone separates you from the background, so only the background gets the swirl.
• The plate gets flaws of its own: an uneven collodion pour, a bare edge, comets, silver stains, developer marks, yellowed varnish and, if you like, 160 years of age.
• The tones are matched to real plates in the Metropolitan Museum of Art.

Everything is computed on your phone. Your picture is never uploaded.

You can have a real tintype made at our studio: fotojockovic.com.