..
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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