Di: HP: Crash: Photo Flash ?
God's Brain
On Mon, 1 Sep 2003 00:18:11 +0100, in alt.conspiracy.princess-diana
banana <banana@REMOVE_THIS.borve.demon.co.uk> wrote:
>In article <FiLUMAEk6lU$Ew...@bozzie.demon.co.uk>, Paul C. Dickie
><p...@bozzie.demon.co.uk> writes
>>In article <mjpTujAOS8T$Ew...@borve.demon.co.uk>, banana <banana@REMOVE_T
>>HIS.borve.demon.co.uk> writes
>>>Key witnesses who will be re-interviewed include those who claimed to
>>>have seen a blinding light flashed at Henri Paul by the driver of a
>>>powerful motorbike, who was never traced.
>>
>>It has been suggested that was an anti-personnel weapon; it may have
>>just been a powerful photographic flash such as the Bowens Boflash or
>>even the multiple flashbulb Bowens Blaster. (http://snurl.com/27d0)
>>
>>>WHERE are the paparazzi photos seized by police at the scene showing a
>>>bright dazzling light, according to claims from Mohamed al Fayed?
>>
>>The sort of flash device I have in mind would be powerful enough to turn
>>night into day.
>
>The anti-personnel weapon gives a considerably brighter flash than any
>photographer's flash, but it's true that some photographic flash devices
>are very bright. But could a very bright photographic flash be used without
>serious risk if used to illuminate a fast-moving car in a tunnel? And would
>it be capable of being focused onto such a fast-moving subject? I don't
>think so, and I don't think any experienced photographer would either.
>
>I have no expertise in this field, but for a post by a photographer arguing
>against the 'photographer's flash' explanation, see:
>
>http://groups.google.com/groups?selm=357aacb0.5317673%40news.dircon.co.uk
>
>by Joe Berenbaum. Joe discusses in detail the idea that the witnessed flash
>was the product not of foul play but rather of the reasonable use of a
>photographic flash:
>
>***BEGIN EXTRACT***
>
><snip>
>
>I just want to respond to the flash question as it raises the issue of
>whether someone was using the flash that was witnessed immediately
>before the crash for photographic purposes. I don't agree that the
>documentary hypothesised as above.
>
>The Carlton documentary compared the flash of a high-power Metz photo
>flashgun such as is typically used by professional photographers with
>the far brighter flash of the anti-personnel flash gun and the witness
>on the Carlton programme said the latter was comparable to what he saw
>immediately preceding the crash, not the former. Even allowing for the
>possibility of a photographer using a flash device with the extremely
>(dangerously) high light output of the latter, the photographic
>possibilities are still very poor in my opinion. I have been an
>amateur photographer for some 20 years and I have used CAT
>(catadioptric) lenses and I would not even consider using one of these
>in such a situation. These are more commonly known as mirror lenses
>and they are very hard to focus accurately even on a slow moving
>subject in strong daylight. They have small apertures, typically f11
>on a 500mm mirror lens which means the the image in the camera
>viewfinder will be darker than with normal lenses- many times darker,
>thus in low light they would be virtually unusable in any event.
>Mirror lenses and "long" lenses generally have very little depth of
>field, ie whatever they are focused on, the region that will appear in
>focus and recognisable is extremely shallow indeed, maybe only inches
>from front to back of the focused and thus recognisable area.
>
>The alternative would be to use a conventional (ie non-mirror) lens-
>this would be easier to focus but in low light still extremely
>difficult, and in low light on a moving subject virtually impossible.
>Using a long focal length conventional lens (often referred to as
>telephoto) I would not consider trying to photograph a subject in low
>light moving at high speed from another fast moving vehicle with such
>a lens. It is just not a sensible proposition- the chances of getting
>a recognisable image are so slim as to make it a pointless excercise.
>With longer focal length lenses (telephoto lenses) that can pull in
>distant details, focusing in less than ideal conditons is difficult
>even with autofocus since the focusing mechanism of even
>state-of-the-art professional cameras tends to "hunt" backwards and
>forwards and fail to "lock on" to the subject in difficult situations.
>Another consideration is that if you attempt to autofocus on the
>occupants of a car in a dark but artifically lit tunnel, the autofocus
>is likely to pick the brightest part of the subject to focus on, which
>in this instance would be the reflections in the car windows of the
>tunnel lighting. Thus the autofocus mechanism would effectively focus
>the camera on a distance some several meters behind the plane of
>correct focus for the car occupants, giving a totally out of focus and
>unrecognisable image of the occupants that would be a blur at best,
>superimposed with a nicely focused and much brighter image of the
>window reflections of the tunnel lighting.
>
>The remaining possibility would be to have a lens set to manual focus
>and set it on a pre-determined distance and try to take the picture
>when you think the subject is at about the right distance from the
>camera To do this you would need to have a predictable subject
>distance and to have some idea of how the situation is going to
>unfold. This is how the famous news shot of a tearful Margaret
>Thatcher leaving No. 10 Downing street in a car moving at slow speed
>tangential to the photographer was obtained, at some distance, and
>with a conventional power flash gun set on manual (maximum strength),
>the lens being pre-focused to an estimated distance. But- that was a
>predictable situation with the subject at a predictable distance and
>no really fast moving elements in the scene at all.
>
>The situation at the crash in the tunnel was very different in just
>about every way. The flash we are talking about before the crash was
>many, many times brighter according to the witness, and the vehicle/s
>were apparently moving at very high speed. So attempting to get a
>picture this way you would get (maybe) one shot and if you were
>extremely lucky, you just might get one usable image, but I think it
>is still so very unlikely that I cannot believe anyone would try this
>and I cannot believe that a professional photograper would come up
>with this method for a serious attempt to get a usable picture.
>
>But- why would anyone, photographer or otherwise, generate such an
>intense flash burst whilst speeding in a dark tunnel anyway? The
>deliberate use of an extremely high-powered flash device in front of a
>fast-moving vehicle in such a tunnel poses an obvious threat to the
>life of the occupants.
>
>***END EXTRACT***
>
><snip>
>
>>>Yesterday a trail of melted metal led to the huge patch of scorched
>>>earth and trees that marks the spot where Andanson's body was found.
>>
>>*Melted* metal?
>
>>>Farmer Julian Christian, 37, who owns the land, was one of the first
>>>at the scene after the alarm had been raised by a nearby army base,
>>>whose sentries spotted smoke on the horizon. The isolation of the
>>>location meant that by the time anyone arrived, the fire had gone out.
>>>Mr Christian said: "I came into this clearing and the car was badly
>>>melted. The glass had shattered, you could still feel the heat and the
>>>driver's body, well, it was hardly there."
>>
>>That does seem to suggest a higher temperature than that of a petrol
>>fire. The phase transition (melting point) of mild steel is over 1000C
>>(though it softens at about 550C) whilst that of aluminium alloy is
>>around 600C.
>
>According to the info at that site (section 4.2), investigators take an
>apparently higher than normal temperature as an indicator of arson). But
>see below.
>
>>On the other hand, the flame temperature of burning petrol
>>is 471 to 560C. (http://snurl.com/27cv)
>
>The flame temperature isn't the whole story. Burning petrol has a
>temperature of over 945°C
>(see: <http://www.firefire.com/Products/glossary/glossary.htm>). The
>melting of metal in cars that have been set on fire is not, AIUI,
>extraordinarily unusual.
>
>--
>banana "You know what I hate the most about you Rowntree? The way
> you give Coca-Cola to your scum, your best teddy-bear to
> Oxfam, then expect us to lick your cold frigid fingers for the
> rest of your cold frigid life." (Mick Travis, 'If...', 1968)
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