Very slow film, electrical sync. and lots of flash powder is my guess.
On Sat, Mar 10, 2012 at 4:52 PM, Chuck Norcutt <
chucknorcutt@xxxxxxxxxxxxxxxx> wrote:
> To my mild surprise the guns were fired electrically. Perhaps it was
> possible to synch the camera with the firing signal.
>
> Chuck Norcutt
>
>
> On 3/10/2012 2:32 PM, Rick Beckrich wrote:
> > .
> >
> > Agree with Mark... I once spent half a day at the Yakima Firing Range
> > trying to
> >
> > capture the flight of the round from an 81mm mortar. Got lots of misses.
> >
> > .
> >
> >
> >
> > On Sat, Mar 10, 2012 at 11:46 AM, Mark Marr-Lyon<mark.marrlyon@xxxxxxxxx
> >wrote:
> >
> >> It's possible that the guns there only ever fired dummy rounds for
> >> practice, so the docent might not have been completely wrong :)
> >> Certainly in wartime, explosive rounds would have been used.
> >>
> >> As for the photo, it looks like Speed Graphics were available in the
> >> 1910s which had a 1/1000 s focal plane shutter. Presumably, fast
> >> enough film also existed to use it. At that shutter speed, the
> >> projectile only moves a foot, and since they're about 4 feet long, 3
> >> feet of the blurred projectile would have been exposed for the entire
> >> shutter duration (not accounting for focal plane shutter oddities,
> >> which could probably be used to advantage), and easily visible in the
> >> photo. The blur at 1/250 s should be pretty noticeable, and the
> >> projectile would look ghostly. If the muzzle flash is providing the
> >> light, then the background of the image would be dark. It's hard to
> >> say more without seeing the photo.
> >>
> >> I've spent a bit of my professional life trying to take photos of
> >> projectiles, and even trying hard to synchronize events it can still
> >> take a fair amount of luck.
> >>
> >> Mark
> >>
> >> On Sat, Mar 10, 2012 at 8:12 AM, Johnny Johnson<theronemmie@xxxxxxxxx>
> >> wrote:
> >>> Thanks Chuck, it seems that our docent that day was less than well
> >> informed
> >>> and that some of the projectiles did include explosive charges. Also,
> the
> >>> maximum projectile weight was ~1/2 ton, not 3/4 ton. Now I wonder what
> >>> other misinformation we were given. Oh well, at least we didn't pay for
> >> the
> >>> service. :-)
> >>>
> >>> Cya,
> >>> Johnny
> >>>
> >>> ---------------------
> >>> Johnny Johnson
> >>> Cleveland, GA
> >>> On Mar 10, 2012 9:57 AM, "Chuck Norcutt"<chucknorcutt@xxxxxxxxxxxxxxxx
> >
> >>> wrote:
> >>>
> >>>> For those of you so inclined here is the entire 136 page "user's
> manual"
> >>>> for the 12-inch Mortar Model 1890MI.
> >>>> <
> >>>>
> >>
> http://www.scribd.com/doc/17375868/TM-9456-12inch-Seacoast-Materiel-12inch-Mortar-M1890MI-Mounted-on-12inch-Mortar-Carriage-M1896MI-and-M1896MII
> >>>>>
> >>>> All of the info about the various forms of ammunition is found on
> pages
> >>>> 77-101 (according to the index) :-)
> >>>>
> >>>> Chuck Norcutt
> >>>>
> >>>>
> >>>> On 3/10/2012 8:52 AM, Johnny Johnson wrote:
> >>>>> Don't know the answer to your question Chuck but when I was there I
> >> was
> >>>>> impressed by the sheer size of the projectiles and the range. If I
> >>>> remember
> >>>>> correctly they were on the order of 3/4 ton each and had a range of
> >> seven
> >>>>> miles with a maximum altitude of ~three miles. They didn't contain
> >>>>> explosives, just depended on the weight of the projectile to do the
> >>>> damage.
> >>>>>
> >>>>> I do remember seeing the photograph that has you puzzled. My only
> >>>> reaction
> >>>>> was to think of how neat it was that they caught the projectile on
> >> film,
> >>>>> not the technicalities of how it was done.
> >>>>>
> >>>>> Cya,
> >>>>> Johnny
> >>>>>
> >>>>> ---------------------
> >>>>> Johnny Johnson
> >>>>> Cleveland, GA
> >>>>> On Mar 10, 2012 8:00 AM, "Chuck Norcutt"<
> >> chucknorcutt@xxxxxxxxxxxxxxxx>
> >>>>> wrote:
> >>>>>
> >>>>>> As a possible answer to my own question it occurred to me that the
> >>>>>> projectiles (at only about 1/300 second after firing) are probably
> >> being
> >>>>>> illuminated by the bright flash of the guns. So the film was
> >> probably
> >>>>>> exposed by the flash of the guns and not the ambient light. Sort of
> >> a
> >>>>>> built-in strobe and not requiring a fast shutter or fast film.
> Sound
> >>>>>> reasonable?
> >>>>>>
> >>>>>> Chuck Norcutt
> >>>>>>
> >>>>>>
> >>>>>> On 3/10/2012 7:34 AM, Chuck Norcutt wrote:
> >>>>>>> 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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