I mentioned looking closely at old photos yesterday. Changes in photographic technology over the years mean changes in what photos show us. For example, the 1906 picture above of the Trinity Building at 111 Broadway (Old Structures Engineering’s home from 2010 to 2017) was obviously taken on a sunny day. As a matter of fact we can tell it was taken on the morning of a sunny day, as we see the shadow of a building on the east side of Broadway across the east end of the building. What interests me are the flags on the roof. A lot of engraving show oversized flags on rooftops between 1880 and 1920, and we sometimes come across old flagpole mounts. But I’ve always assumed that at least some of those engravings are exaggerations, so it’s good to see a photo showing two large flags on one building, as well as what looks like another large flag on the next big building to the north.
We’d expect a modern photo taken outside on a sunny day to have a fast shutter speed, in the ballpark of 1/250 of a second or maybe less. (The switch from film to digital has eliminated the disadvantages of fast film.) But flags don’t flutter that fast, and we can actually see the flutter as increasing blurriness of the flags the further we look away from the flagpole. The days of having to wait for thirty seconds or more for an exposure were long gone by 1906, but film was still, by our standards, quite slow. Note that the carriages and people in Broadway are blurred to the point of ghosting, suggesting we’re looking at an exposure in the ballpark of a half second to two seconds. The flags aren’t blurry because of a hurricane wind, they’re blurry because of time.
In 1905, a similar photo was taken a few blocks to the north, looking east across City Hall Park:
Note the bare flagpoles, feeding my suspicion that they were not always used. Again, the shadows are coming from behind us, so it’s another sunny morning. And the flags and people are crisp and sharp-edged, and a bird was caught in mid-flight (at the very top, just left of center) so this was a faster exposure. I’ll assume that the cameras of 1905 and 1906 weren’t very different, so why is this one sharper? Different film? More likely, a wider aperture to allow for a faster shutter?
Finally, an indoor photo from 1902, in the typewriting (i.e., secretarial) department of the National Cash Register Company, in Dayton, Ohio:
The effect here is subtle, but visible. The women are obviously not moving much, as they’re focused on their typewriters or papers. The woman at the far left of the first row moved her head during the shot, as her face and hair are blurred while the rest of her is not. The same is true of the woman second from the left on the second row. There are a bunch of incandescent-bulb fixtures overhead, but most of the light is coming from the very large windows on the left. The fact that all of the women are wearing white shirts (shirtwaists, in the language of the day) with what appear to be white aprons over their regular clothes has made them burn the film a bit, so they are less clear than the dark wood tables and the black-enameled typewriters. So we’re probably looking at a fairly short exposure with a wide aperture, but long enough for two women to move perceptibly.
Does any of this matter? Probably not in the three examples I’ve given here, but it can sometimes when you’re trying to decipher an old photo.