Velocity Reviews > "The exposures are at 1/100,000,000ths of a second"

# "The exposures are at 1/100,000,000ths of a second"

William Graham
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Posts: n/a

 02-16-2006

"Peter Irwin" <(E-Mail Removed)> wrote in message
news:dt0p7p\$mj\$(E-Mail Removed)...
> In rec.photo.equipment.35mm William Graham <(E-Mail Removed)> wrote:
>>
>>
>> I don't know how I would go about building a shutter that could take a
>> picture at one, one millionth of a second.

>
> Two crossed polarizers with something in between which twists
> polarization in response to electricity or magnetism.
> The Kerr cell is the most common example. Someone posted that
> these shots used a Faraday shutter which is similar in concept.
>
>> Also, I don't think that kind of
>> speed would be necessary. After all, the blast can't be that much
>> brighter
>> than the sun, which is simply a continuous nuclear explosion. So, taking
>> a
>> picture of a nuclear blast would be like taking a photograph of the sun.

>
> The sun is nearly half a million times brighter than sunlight reflected
> from
> a grey card. Staring directly at the sun can cause permanent damage
> to your eyes in a remarkably short time.
>
>> It's true that it isn't the brightness that they were worried about, but
>> the
>> ability to freeze the motion. So the question is, how fast must the
>> shutter
>> be in order to do this, and do they have film that is fast enough to
>> record
>> it at that speed. I think that a millionth of a second is way too fast to

>
> Atomic explosions are darned quick, especially at the very start.
> A small atomic bomb can produce a 90 foot fireball in 1/10000th
> of a second. If you want to freeze that fireball one millionth
> of a second isn't too fast at all.
>
> This was all done half a century ago. It worked fine.
>
>> We certainly don't have any film
>> fast enough to record the sun at a millionth of a second, do we?

>
> If you were to shoot the disc of the sun on ISO 100 slide film
> at f/16 and one millionth of a second, it would still show
> as a nearly clear spot on the film. The sun is insanely bright.
>
> Peter.

Perhaps you are right....I've always used neutral density filters to shoot
eclipses........I did see an observatory that specialized in the sun near
Stanford University....They projected it with optics from the roof of the
building onto a table about 30 inches high. The image was about two feet in
diameter, and was marvelously clear and sharp....You could see solar flares
in real time.....(8 minute delayed, of course.)

David Littlewood
Guest
Posts: n/a

 02-16-2006
In article <(E-Mail Removed) .com>, Mike
Henley <(E-Mail Removed)> writes
>
>I'm back, did you miss me?
>
>What would you shoot at such 1/100,000,000 shutter speed?
>
>But of course, perhaps the most spectacular thing possible, an atomic
>blast! The "first few fractions of an atomic bomb upon detonation".
>
>Enjoy
>
>http://www.rapidnewswire.com/atom.htm
>

Anyone seriously interested in the general subject of high-speed
photography may care to get hold of a copy of "High Speed Photography
and Photonics", Ed Sidney F Ray, Focal Press 1997, ISBN 0 2405 1479 3
(The may be a later edition for all I know.

However, it would only be fair to point out that it actually has little
that name. Vast amounts of useful detail on the general subject though.

David
--
David Littlewood

Kennedy McEwen
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Posts: n/a

 02-16-2006
In article <(E-Mail Removed)>, William
Graham <(E-Mail Removed)> writes
>
>I did see an observatory that specialized in the sun near
>Stanford University....They projected it with optics from the roof of the
>building onto a table about 30 inches high. The image was about two feet in
>diameter, and was marvelously clear and sharp....You could see solar flares
>in real time.....(8 minute delayed, of course.)
>

There is also the 150m solar telescope at Mt Wilson , which opens daily
to the public, and produces images about that size - quite impressive if
you happen to visit during high activity days. It has a webcam mounted
on the top giving updates at 4minute intervals of the Mt Wilson site.
http://www.astro.ucla.edu/%7Eobs/towercam.htm
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's ****ed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)

Kennedy McEwen
Guest
Posts: n/a

 02-16-2006
In article <(E-Mail Removed)>, William Graham
<(E-Mail Removed)> writes
>
>I don't know how I would go about building a shutter that could take a
>picture at one, one millionth of a second. Also, I don't think that kind of
>speed would be necessary. After all, the blast can't be that much brighter
>than the sun, which is simply a continuous nuclear explosion.

Oh yes it can!

>So, taking a
>picture of a nuclear blast would be like taking a photograph of the sun.

What you see when you look at the sun is not actually the nuclear
reaction, but the photosphere, which is hot gases at about 5300degC but
considerably colder than the 10 million or so degC at the heart of the
sun where the nuclear reactions are occurring. Just remember that the
only thing that stops the sun from collapsing under its own weight is
the pressure produced in the core by the nuclear generated light - that
is a lot of light.

There are lots of things that are brighter than the sun here on earth,
and they don't need to be nuclear sources. My hefty old flashgun, for
example, has a flash duration at full power of 1/250th of a second and
ISO100 GN of 56. So it produces enough light to match the "sunny 16
rule" at about 1m range - making it just as bright at that range as the
sun for the time it is lit. Half a metre and it is 4 times brighter
than the sun, and so on.

>It's true that it isn't the brightness that they were worried about, but the
>ability to freeze the motion. So the question is, how fast must the shutter
>be in order to do this, and do they have film that is fast enough to record
>it at that speed. I think that a millionth of a second is way too fast to
>answer either question. IOW, they don't need that kind of speed to freeze
>the motion, and even if they did, they don't have any film fast enough to be
>able to record the event at that speed. We certainly don't have any film
>fast enough to record the sun at a millionth of a second, do we? Most high
>speed photographs are frozen in time by the strobe light, and not by the
>shutter.

So, what you are saying is that the strobe light used to capture such
images must be many times brighter at the scene than the sun would be,
which is certainly true, as witnessed by the rough estimate given above.
But even those powerful strobes are trivially dim compared to a nuclear
flash.

- there certainly did have enough light for that shutter speed, and at
quite a large f/# as well I expect, given that this is a 10ft focal
length optic!
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's ****ed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)

William Graham
Guest
Posts: n/a

 02-16-2006

"Kennedy McEwen" <(E-Mail Removed)> wrote in message
news:WL2\$(E-Mail Removed)...
> In article <(E-Mail Removed)>, William Graham
> <(E-Mail Removed)> writes
>>
>>I don't know how I would go about building a shutter that could take a
>>picture at one, one millionth of a second. Also, I don't think that kind
>>of
>>speed would be necessary. After all, the blast can't be that much brighter
>>than the sun, which is simply a continuous nuclear explosion.

>
> Oh yes it can!
>
>>So, taking a
>>picture of a nuclear blast would be like taking a photograph of the sun.

>
> What you see when you look at the sun is not actually the nuclear
> reaction, but the photosphere, which is hot gases at about 5300degC but
> considerably colder than the 10 million or so degC at the heart of the sun
> where the nuclear reactions are occurring. Just remember that the only
> thing that stops the sun from collapsing under its own weight is the
> pressure produced in the core by the nuclear generated light - that is a
> lot of light.
>
> There are lots of things that are brighter than the sun here on earth, and
> they don't need to be nuclear sources. My hefty old flashgun, for
> example, has a flash duration at full power of 1/250th of a second and
> ISO100 GN of 56. So it produces enough light to match the "sunny 16 rule"
> at about 1m range - making it just as bright at that range as the sun for
> the time it is lit. Half a metre and it is 4 times brighter than the sun,
> and so on.
>
>>It's true that it isn't the brightness that they were worried about, but
>>the
>>ability to freeze the motion. So the question is, how fast must the
>>shutter
>>be in order to do this, and do they have film that is fast enough to
>>record
>>it at that speed. I think that a millionth of a second is way too fast to
>>answer either question. IOW, they don't need that kind of speed to freeze
>>the motion, and even if they did, they don't have any film fast enough to
>>be
>>able to record the event at that speed. We certainly don't have any film
>>fast enough to record the sun at a millionth of a second, do we? Most high
>>speed photographs are frozen in time by the strobe light, and not by the
>>shutter.

>
> So, what you are saying is that the strobe light used to capture such
> images must be many times brighter at the scene than the sun would be,
> which is certainly true, as witnessed by the rough estimate given above.
> But even those powerful strobes are trivially dim compared to a nuclear
> flash.
>
> In other words, your own observation contradicts what you are asserting -
> there certainly did have enough light for that shutter speed, and at quite
> a large f/# as well I expect, given that this is a 10ft focal length
> optic!

So all I guess I need to know is how to get a 1/millionth second
shutter.....I don't know how to rotate a polarizer that fast, and I don't
understand the other faraday reference.....I know that I used to use a
Tectronics capture scope that couldn't even blank off the erase pulse, which
used to destroy my vision in a darkened room every few seconds.....I don't
know why they didn't blank that off with a standard mechanical shutter, much
less a millionth second electronic one.....

William Graham
Guest
Posts: n/a

 02-16-2006

"William Graham" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>
> "Kennedy McEwen" <(E-Mail Removed)> wrote in message
> news:WL2\$(E-Mail Removed)...
>> In article <(E-Mail Removed)>, William Graham
>> <(E-Mail Removed)> writes
>>>
>>>I don't know how I would go about building a shutter that could take a
>>>picture at one, one millionth of a second. Also, I don't think that kind
>>>of
>>>speed would be necessary. After all, the blast can't be that much
>>>brighter
>>>than the sun, which is simply a continuous nuclear explosion.

>>
>> Oh yes it can!
>>
>>>So, taking a
>>>picture of a nuclear blast would be like taking a photograph of the sun.

>>
>> What you see when you look at the sun is not actually the nuclear
>> reaction, but the photosphere, which is hot gases at about 5300degC but
>> considerably colder than the 10 million or so degC at the heart of the
>> sun where the nuclear reactions are occurring. Just remember that the
>> only thing that stops the sun from collapsing under its own weight is the
>> pressure produced in the core by the nuclear generated light - that is a
>> lot of light.
>>
>> There are lots of things that are brighter than the sun here on earth,
>> and they don't need to be nuclear sources. My hefty old flashgun, for
>> example, has a flash duration at full power of 1/250th of a second and
>> ISO100 GN of 56. So it produces enough light to match the "sunny 16
>> rule" at about 1m range - making it just as bright at that range as the
>> sun for the time it is lit. Half a metre and it is 4 times brighter than
>> the sun, and so on.
>>
>>>It's true that it isn't the brightness that they were worried about, but
>>>the
>>>ability to freeze the motion. So the question is, how fast must the
>>>shutter
>>>be in order to do this, and do they have film that is fast enough to
>>>record
>>>it at that speed. I think that a millionth of a second is way too fast to
>>>answer either question. IOW, they don't need that kind of speed to freeze
>>>the motion, and even if they did, they don't have any film fast enough to
>>>be
>>>able to record the event at that speed. We certainly don't have any film
>>>fast enough to record the sun at a millionth of a second, do we? Most
>>>high
>>>speed photographs are frozen in time by the strobe light, and not by the
>>>shutter.

>>
>> So, what you are saying is that the strobe light used to capture such
>> images must be many times brighter at the scene than the sun would be,
>> which is certainly true, as witnessed by the rough estimate given above.
>> But even those powerful strobes are trivially dim compared to a nuclear
>> flash.
>>
>> In other words, your own observation contradicts what you are asserting -
>> there certainly did have enough light for that shutter speed, and at
>> quite a large f/# as well I expect, given that this is a 10ft focal
>> length optic!

>
> So all I guess I need to know is how to get a 1/millionth second
> shutter.....I don't know how to rotate a polarizer that fast, and I don't
> understand the other faraday reference.....I know that I used to use a
> Tectronics capture scope that couldn't even blank off the erase pulse,
> which used to destroy my vision in a darkened room every few seconds.....I
> don't know why they didn't blank that off with a standard mechanical
> shutter, much less a millionth second electronic one.....
>

Ah......I found some information on it here:

http://www.rit.edu/~andpph/text-high-speed.html

Magneto-optical Shutter

This utilizes the Faraday effect, i.e., the rotation of the plane of
polarization of light passing through a transparent medium in a magnetic
field.

To use the Faraday effect, a suitable medium in a magnetic coil is placed
between crossed polarizers. Dense flint glass is generally used, since it
shows considerable rotation of the plane of polarization for a given
magnetic field and is convenient to handle. With no current in the coil,
there is no magnetic field, no rotation of the plane of polarization occurs,
and therefore no light is transmitted. When a suitable current is applied
(often 1,000 amperes needing 10,000 volts) the plane of polarization is
rotated until it agrees with the second polarizer, and the maximum light is
transmitted. This current can be supplied by discharging a capacitor through
the coil using a spark gap as a switch. The time of the discharge depends on
the capacitor size, the voltage, and the number of turns in the coil.
Exposure times down to 1 microsecond have been achieved.

no_name
Guest
Posts: n/a

 02-17-2006
Andy Williams wrote:

> William Graham wrote:
>
>
>>I don't know how I would go about building a shutter that could take a
>>picture at one, one millionth of a second.

>
>
> It is not a shutter in the ordinary mechanical sense, of course. It's
> an electronic effect. Google Kerr effect.
>
>
>>Also, I don't think that kind of
>>speed would be necessary. After all, the blast can't be that much brighter
>>than the sun, which is simply a continuous nuclear explosion. So, taking a
>>picture of a nuclear blast would be like taking a photograph of the sun.

>
>
> You are ignoring the inverse square law. The Sun is 93 million miles
> away. A nuclear explosion can be photographed from seven miles away.
> The fireball is about 60 - 100 million degrees C, 10,000 times hotter
> and about 10^16 times brighter than the surface of the sun.

And the reason for the millionth of a second "shutter speeds" isn't to
deal with the brightness, but to deal with TIME.

They wanted discrete images of the fireball in very small increments of
time, so they could see how it developed.

Dennis P. Harris
Guest
Posts: n/a

 02-17-2006
On Thu, 16 Feb 2006 14:06:02 -0800 in rec.photo.digital, "William
Graham" <(E-Mail Removed)> wrote:

> So all I guess I need to know is how to get a 1/millionth second
> shutter.....I don't know how to rotate a polarizer that fast,

you use a polarizer that filters light in a particular direction
when electric current is applied, use a high voltage pulse of
short duration to trigger it.

Kennedy McEwen
Guest
Posts: n/a

 02-17-2006
In article <(E-Mail Removed)>, William Graham
<(E-Mail Removed)> writes
>
>
>So all I guess I need to know is how to get a 1/millionth second
>shutter.....I don't know how to rotate a polarizer that fast, and I don't
>understand the other faraday reference.....I know that I used to use a
>Tectronics capture scope that couldn't even blank off the erase pulse, which
>used to destroy my vision in a darkened room every few seconds.....I don't
>know why they didn't blank that off with a standard mechanical shutter, much
>less a millionth second electronic one.....
>

The Kerr cell is only one way of achieving this sort of shutter time. I
posted a link to a gated intensifier camera the other day with a 10nS
gate period (which is the electronic equivalent of the shutter).

http://www.linuxdevices.com/articles/AT2171151224.html

I worked with a similar system based on an intensified isocon camera for
low light imaging back in the early 80's, although that had been in
service with the RAF for at least a decade by then.

There are equivalent solid state devices available these days, some of
which are used for laser gated imaging, for example in cost effective
undersea surveillance from an aircraft. In such systems the rapid
shutter speed, coupled to a pulsed laser illumination source, permits
the camera shutter to be closed when the laser pulse is reflected by the
sea surface, but opened when the reflection from the sea bed returns.
This effectively eliminated the reflection from the ocean surface from
the images, permitting clear images of the sea bed to be obtained.
Obviously, since the sea water rapidly attenuates the laser light there
are limits as to how deep you can image, hence the need for high
sensitivity as well as fast shutter speed.
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's ****ed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)

Dave Martindale
Guest
Posts: n/a

 02-17-2006
"William Graham" <(E-Mail Removed)> writes:

>So all I guess I need to know is how to get a 1/millionth second
>shutter.....I don't know how to rotate a polarizer that fast, and I don't

You need a substance that changes the amount it rotates polarized light
depending on the voltage applied. Liquid crystals work that way, but
they're too slow for this use. But there are other faster
technologies.

>I know that I used to use a
>Tectronics capture scope that couldn't even blank off the erase pulse, which
>used to destroy my vision in a darkened room every few seconds.....I don't
>know why they didn't blank that off with a standard mechanical shutter, much
>less a millionth second electronic one.....

And how would you go about that? The erase is done by flooding the
screen with electrons for a significant fraction of a second, to
equalize the charge on the storage grid behind the screen. The only way
to block that is have a shutter between your eye and the screen - which
means a full-screen-sized shutter (impractical if mechanical, expensive
if electronic), or forcing you to look through a small hole that can
have a small shutter protecting it.

Anyway, aren't you glad that these have mostly been replaced by digital
storage? Now the image doesn't degrade no matter how long you look at
it, and you don't get fainter images at faster writing speeds, and you
can even print the waveform or save it on your PC, instead of having to
photograph it on film before it decayed. (See, there's a camera in this
posting after all).

Dave