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OT: Optics/Physics question

Started by Tim Wescott September 6, 2013
This picture:

https://en.wikipedia.org/wiki/File:Bullet_coming_from_S%26W.jpg

Shows a gun being fired, using a high-speed flash.

However, it clearly shows detail in the flame that's blowing out sideways 
from the cylinder-barrel junction.  My understanding of that sort of 
flame is that it is glowing from internal light, which means that the 
flash cannot stop its action.

Indeed, if you got the light bright enough to overwhelm the light from 
the flame, it would be gray or black, not orange.

So -- what gives?  A fast shutter that captures the flame, while 
somewhere in the middle of it all the flash provides enough light to 
capture the non-glowing parts of the picture?

Thanks.

-- 

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

"Tim Wescott" <tim@seemywebsite.really> wrote in message 
news:3LSdndFbgvzaibfPnZ2dnUVZ5rgAAAAA@giganews.com...
> This picture: > > https://en.wikipedia.org/wiki/File:Bullet_coming_from_S%26W.jpg > > Shows a gun being fired, using a high-speed flash. > > However, it clearly shows detail in the flame that's blowing out sideways > from the cylinder-barrel junction. My understanding of that sort of > flame is that it is glowing from internal light, which means that the > flash cannot stop its action. > > Indeed, if you got the light bright enough to overwhelm the light from > the flame, it would be gray or black, not orange. > > So -- what gives? A fast shutter that captures the flame, while > somewhere in the middle of it all the flash provides enough light to > capture the non-glowing parts of the picture? > > Thanks. > > -- > > Tim Wescott > Wescott Design Services > http://www.wescottdesign.com >
The camera shutter is open for a (relatively) long time. That is why you see the light from the muzzle flash.
On 09/06/2013 01:43 PM, Tim Wescott wrote:
> This picture: > > https://en.wikipedia.org/wiki/File:Bullet_coming_from_S%26W.jpg > > Shows a gun being fired, using a high-speed flash. > > However, it clearly shows detail in the flame that's blowing out sideways > from the cylinder-barrel junction. My understanding of that sort of > flame is that it is glowing from internal light, which means that the > flash cannot stop its action. > > Indeed, if you got the light bright enough to overwhelm the light from > the flame, it would be gray or black, not orange. > > So -- what gives? A fast shutter that captures the flame, while > somewhere in the middle of it all the flash provides enough light to > capture the non-glowing parts of the picture? > > Thanks. >
Probably. An interline-transfer CCD, or some types of CMOS sensor, can have really fast shuttering. You'd give it one clock to transfer sideways from the light pixels into the (shielded) transfer array, then shift it out slowly to keep the noise low. The shutter speed was probably faster than the flash. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message 
news:522A16D6.90700@electrooptical.net...
> On 09/06/2013 01:43 PM, Tim Wescott wrote: >> This picture: >> >> https://en.wikipedia.org/wiki/File:Bullet_coming_from_S%26W.jpg >> >> Shows a gun being fired, using a high-speed flash. >> >> However, it clearly shows detail in the flame that's blowing out sideways >> from the cylinder-barrel junction. My understanding of that sort of >> flame is that it is glowing from internal light, which means that the >> flash cannot stop its action. >> >> Indeed, if you got the light bright enough to overwhelm the light from >> the flame, it would be gray or black, not orange. >> >> So -- what gives? A fast shutter that captures the flame, while >> somewhere in the middle of it all the flash provides enough light to >> capture the non-glowing parts of the picture? >> >> Thanks. >> > > Probably. An interline-transfer CCD, or some types of CMOS sensor, can > have really fast shuttering. You'd give it one clock to transfer sideways > from the light pixels into the (shielded) transfer array, then shift it > out slowly to keep the noise low. > > The shutter speed was probably faster than the flash. > > Cheers > > Phil Hobbs >
The flash is MUCH faster than the shutter.
On Fri, 06 Sep 2013 13:54:30 -0400, Phil Hobbs wrote:

> On 09/06/2013 01:43 PM, Tim Wescott wrote: >> This picture: >> >> https://en.wikipedia.org/wiki/File:Bullet_coming_from_S%26W.jpg >> >> Shows a gun being fired, using a high-speed flash. >> >> However, it clearly shows detail in the flame that's blowing out >> sideways from the cylinder-barrel junction. My understanding of that >> sort of flame is that it is glowing from internal light, which means >> that the flash cannot stop its action. >> >> Indeed, if you got the light bright enough to overwhelm the light from >> the flame, it would be gray or black, not orange. >> >> So -- what gives? A fast shutter that captures the flame, while >> somewhere in the middle of it all the flash provides enough light to >> capture the non-glowing parts of the picture? >> >> Thanks. >> >> > Probably. An interline-transfer CCD, or some types of CMOS sensor, can > have really fast shuttering. You'd give it one clock to transfer > sideways from the light pixels into the (shielded) transfer array, then > shift it out slowly to keep the noise low. > > The shutter speed was probably faster than the flash.
It was an air-gap flash. Note the fact that you can see the flame, and you can see the bullet without any visible streaking or blurring. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
On 9/6/2013 2:20 PM, tm wrote:
> > "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message > news:522A16D6.90700@electrooptical.net... >> On 09/06/2013 01:43 PM, Tim Wescott wrote: >>> This picture: >>> >>> https://en.wikipedia.org/wiki/File:Bullet_coming_from_S%26W.jpg >>> >>> Shows a gun being fired, using a high-speed flash. >>> >>> However, it clearly shows detail in the flame that's blowing out >>> sideways >>> from the cylinder-barrel junction. My understanding of that sort of >>> flame is that it is glowing from internal light, which means that the >>> flash cannot stop its action. >>> >>> Indeed, if you got the light bright enough to overwhelm the light from >>> the flame, it would be gray or black, not orange. >>> >>> So -- what gives? A fast shutter that captures the flame, while >>> somewhere in the middle of it all the flash provides enough light to >>> capture the non-glowing parts of the picture? >>> >>> Thanks. >>> >> >> Probably. An interline-transfer CCD, or some types of CMOS sensor, >> can have really fast shuttering. You'd give it one clock to transfer >> sideways from the light pixels into the (shielded) transfer array, >> then shift it out slowly to keep the noise low. >> >> The shutter speed was probably faster than the flash. >> >> Cheers >> >> Phil Hobbs >> > > The flash is MUCH faster than the shutter. > >
You can get shutter speeds of 1 us with an interline transfer CCD. What sort of flash are you thinking of? Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message 
news:l0e5ag$lgo$1@dont-email.me...
> On 9/6/2013 2:20 PM, tm wrote: >> >> "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message >> news:522A16D6.90700@electrooptical.net... >>> On 09/06/2013 01:43 PM, Tim Wescott wrote: >>>> This picture: >>>> >>>> https://en.wikipedia.org/wiki/File:Bullet_coming_from_S%26W.jpg >>>> >>>> Shows a gun being fired, using a high-speed flash. >>>> >>>> However, it clearly shows detail in the flame that's blowing out >>>> sideways >>>> from the cylinder-barrel junction. My understanding of that sort of >>>> flame is that it is glowing from internal light, which means that the >>>> flash cannot stop its action. >>>> >>>> Indeed, if you got the light bright enough to overwhelm the light from >>>> the flame, it would be gray or black, not orange. >>>> >>>> So -- what gives? A fast shutter that captures the flame, while >>>> somewhere in the middle of it all the flash provides enough light to >>>> capture the non-glowing parts of the picture? >>>> >>>> Thanks. >>>> >>> >>> Probably. An interline-transfer CCD, or some types of CMOS sensor, >>> can have really fast shuttering. You'd give it one clock to transfer >>> sideways from the light pixels into the (shielded) transfer array, >>> then shift it out slowly to keep the noise low. >>> >>> The shutter speed was probably faster than the flash. >>> >>> Cheers >>> >>> Phil Hobbs >>> >> >> The flash is MUCH faster than the shutter. >> >> > You can get shutter speeds of 1 us with an interline transfer CCD. What > sort of flash are you thinking of? > > Cheers > > Phil Hobbs > > --
You can see from the lit gasses that the exposure is in the ms range but the bullet is completely stopped. You can even see the rifling lands on the bullet. It is an air spark gap discharge lasting less than a microsecond. I'd bet it is using a standard consumer CCD camera. In a dark room, you open the shutter when the when the trigger is pulled and after a delay, the flash is fired. I do the same thing with a flash x-ray and an ordinary Nikon digital camera. The x-ray pulse is only 60 ns long. It's pretty neat. If you are versed in using high voltage, anyone could set it up with little funds. Look up "Marx" generator. tm
> https://en.wikipedia.org/wiki/Air-gap_flash
Typical values are 0.05 &micro;F capacity, 0.02 &micro;H inductance, 10 J energy, 0.5 &micro;s duration and about 20 MW power ------------- I think a flash sync at these speeds would be difficult, so I vote for the darkened room and the fast flash. Then again, I voted for Gore, so I am used to my vote not counting.
>"The flash is MUCH faster than the shutter. "
My doubts lie with the timing. This because I notice the (gunpowder) flash coming from around the cylinder but not out of the muzzle. Something "closed that shutter" before that happened because the flash does not illuminate the "flame" of course.
On 2013-09-07, jurb6006@gmail.com <jurb6006@gmail.com> wrote:
>>"The flash is MUCH faster than the shutter. " > > My doubts lie with the timing. This because I notice the (gunpowder) > flash coming from around the cylinder but not out of the muzzle. > Something "closed that shutter" before that happened because the flash > does not illuminate the "flame" of course.
Based on that do you conclude the bullet seen in the photo was not the one that was fired by the explosion that caused the flash from the back of the barrel? for do you have some other explanation for that. -- &#9858;&#9859; 100% natural --- news://freenews.netfront.net/ - complaints: news@netfront.net ---