Granted I haven't seen the photo, I would venture that it was not "captured
on film" but "painted on paper" using retouching ink. Photoshop has much to
answer for, part of which is the assumption that before Photoshop there was
no way to 'improve' a photo. I have seen, nay held in my own hands, prints
from a national newspaper (which I think is respected for not bending the
truth) bearing the most obvious evidence of gross re-touching to accentuate
the lines of the lapel on a dark suit jacket - as one instance that sticks
in my mind. The intent was to make the image reproducible using the
newsprint technology of the day - letterpress printing at maybe 30dpi!
So my vote - no shutter speed mystery at all!
Piers
-----Original Message-----
From: Chuck Norcutt [mailto:chucknorcutt@xxxxxxxxxxxxxxxx]
Sent: 10 March 2012 12:34
To: Olympus mail list
Subject: [OM] A shutter speed mystery
Yesterday we went with some friends to Fort DeSoto Park for a picnic and a
bit of beach lounging. <http://en.wikipedia.org/wiki/Fort_Desoto>
While a very large public park today, Fort DeSoto was originally constructed
between 1898-1906 as a coastal defense battery to protect Tampa Bay. If you
scroll to the bottom of the page linked above you'll see some of the
artillery and mortars originally installed here and at Fort Dade a short
distance away. With 12" bores the mortars are rather impressive beasts.
They were first fired in 1903 and were deactivated not later than 1917.
In a long corridor of historic photographs of the guns and emplacements
there is one very faded shot of two mortars being fired at the same time.
Much to my amazement the projectiles of both guns are clearly visible
perhaps some 30 feet above the muzzles. According to the details I've been
able to find about these guns the muzzle velocity ranges from about 1,000 to
1,500 feet/second depending on the weight of the projectiles whose length
ranges from about 3-4 feet.
Now the shutter speed mystery. How was this photo taken? At 1/500 second
the projectiles moving at 1,000 feet/second move 2 feet or 4 feet at 1/250
second. The angle of view from the camera's position probably creates some
foreshortening of the projectiles but it *appears* to me that the shutter
speed would have been not longer than 1/250. I don't know whether shutters
of the period operated that fast but, even if they did, I don't know how it
would have been captured on a film emulsion of the time.
So, how was this photo taken?
Chuck Norcutt
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