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Old 22 May 2013, 02:09 PM
A Turtle Named Mack's Avatar
A Turtle Named Mack A Turtle Named Mack is offline
Join Date: 21 June 2007
Location: Marietta, GA
Posts: 21,451

I did some searching on the exposure time. I had long heard that the reason for lack of smiling was the 'very long' exposure time needed - I had been told it was over an hour. Not so. The first commercial process, daguerreotype, required up to fifteen minutes exposure at first but was reduced to about a minute.

Exposure times for the earliest daguerreotypes ranged from three to fifteen minutes, making the process nearly impractical for portraiture. Modifications to the sensitization process coupled with the improvement of photographic lenses soon reduced the exposure time to less than a minute.
In 1850 a much faster and more detailed process known as Ambrotype was patented and soon displaced daguerreotype, and in turn, before the Civil War (1861-65 for our non-US readers), tintype was developed. According to the link below, even modern versions of tintypes require 5-10 seconds exposure in bright daylight. We can expect the exposure time would be substantially more with less-intense fire-based light available for 1800s indoor photography (candles, oil lamps, gas lights, etc). As noted in the link, even the 5-10 seconds is too long for someone to hold a smile perfectly still for an unblurred photograph (unless of course, they have trained as a flight attendant).
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