Olympus-OM
[Top] [All Lists]

Re: [OM] A shutter speed mystery

Subject: Re: [OM] A shutter speed mystery
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Sat, 10 Mar 2012 16:52:43 -0500
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
>>>>>>>
>>>>>> --
>>>>>> _________________________________________________________________
>>>>>> Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
>>>>>> Archives: http://lists.thomasclausen.net/mailman/private/olympus/
>>>>>> Themed Olympus Photo Exhibition: http://www.tope.nl/
>>>>>>
>>>>>>
>>>> --
>>>> _________________________________________________________________
>>>> Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
>>>> Archives: http://lists.thomasclausen.net/mailman/private/olympus/
>>>> Themed Olympus Photo Exhibition: http://www.tope.nl/
>>>>
>>>>
>>> --
>>> _________________________________________________________________
>>> Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
>>> Archives: http://lists.thomasclausen.net/mailman/private/olympus/
>>> Themed Olympus Photo Exhibition: http://www.tope.nl/
>>>
>> --
>> _________________________________________________________________
>> Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
>> Archives: http://lists.thomasclausen.net/mailman/private/olympus/
>> Themed Olympus Photo Exhibition: http://www.tope.nl/
>>
>>
-- 
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/

<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz