Photographs | History Detectives | PBS

Informative Details

How To

Analyze photos

Mission

Know the rogue's gallery.

Briefing

Whether you find a photo in the attic, or consider buying one at auction, how do you know what you have? 

First try to identify the era it’s from:

Daguerreotype 1839-1860

Daguerreotypes used a direct-positive process which made an image on a piece of copper that had been plated with silver. Early daguerreotypes took three to 15 minutes to appear, which made them impractical for portraiture. Is it a daguerreotype? A piece of writing paper placed in front of the surface will be reflected in reverse. They often are tarnished around the edges.

Ambrotype 1854-1865 

This process produced a glass negative, which when held against a black background would produce a positive image. It had a number of advantages over the daguerreotype, including a reduced exposure time, making it more popular for portraiture as the subject would not have to sit still as long as with a daguerreotype. It took the reigns over from the daguerreotype in popularity, only to be quickly supplanted by the much cheaper and easier to produce tintype. Hand-tinted ambrotypes were common. Is it an ambrotype? If you take an ambrotype out of the case and hold it up to the light, you should be able to see through it, as it was printed on glass. Often, black paint on the back of the photo has begun to peel or crack.

Tintype 1856-1920

Typically made on a thin iron (not tin!) plate, it's better called a "ferrotype" or "melainotype." Compared with earlier methods of photography, tintypes cost very little to make and buy. As they were produced on iron instead of glass, they became very popular during the Civil War, when soldiers would send home photos of themselves in uniform. It is visually difficult to tell a tintype from an ambrotype. A quick way to tell if a tintype is real? A magnet will be attracted to it.

History Detectives Tips

  • Are you sure that photo is really a photo? You should not be able to see printing "dots" when you look with a magnifying glass.
  • Caveat Emptor: Buying old photographs without seeing them up close is risky business. There are a lot of fakes on the market.
  • Want to learn more about a local photographer? Craig's Daguerrian Registry has lists of many American photographers from 1850-1960.
  • Protect your photos: Keep them out of direct sunlight and away from hot and cold extremes. Wrap the union case in a soft cloth to protect it from damage.

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