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-   -   Firing a gun- Can you slow it to ee the bullet? (https://www.dvinfo.net/forum/canon-xl-gl-series-dv-camcorders/39501-firing-gun-can-you-slow-ee-bullet.html)

Forbes Hansen February 14th, 2005 08:58 PM

Firing a gun- Can you slow it to ee the bullet?
 
I was wondering that with the 15000 shutter speeds are you even able to see the shot. If you do it the screen goes black.

What is the point?

Are oyou able to track a bullet in 60i with that shutter speed. If so we wanted to do ballistics testing for a Senior Project. Different bullets on different surfaces. And we wanted to know if that was possible?

Xiaoli Wang February 14th, 2005 09:24 PM

I don't think it works like a still camera. My understanding is that it is still resolving only 60 interlaced frames at a time, far too slow to capture a bullet in mid air, and the shutter speed is just there cut off excessive light. I also think the shutter is electronic.

Stuff like that has to do more with FPS. If your camera could do 15000FPS it would probably work.

Forbes Hansen February 14th, 2005 09:34 PM

would that take a huge amout of of space on you comp?

Mark Sasahara February 14th, 2005 10:21 PM

The problem is you wouldn't be able to capture the image with the XL2. You would need a high speed camera that can do thousands of pictures per second, something like a Fastax, Hi-Cam, or Red Lake camera. The XL2 can only do 24P, 30i and 60i, far too slow to capture an event that fast.

Jeff Miller February 14th, 2005 10:47 PM

I asked this on another board, I was working on taping slo-mo explosions.

Basically a high shutter speed is not like a high frame rate. You need something like a Varicam or high speed 16mm and that stuff is total bank.

Having a stupid-high shutter speed can be viewable if you baste the subject in light but from my experience made things look _worse_ (at least concerning the look I wanted). You won't see every millisecond of an action with consumer cameras, even the slower explosions I was taping go under a few changes within the first frame. Still looked at least a bit cool under slow motion :}
(this was back on my OpXi)

Greg Boston February 15th, 2005 03:05 AM

Forbes,

Think of high speed shutter as 'freezing' the motion blur of something. However, like others said, you need a high frame rate to capture the entire event because so much happens from frame to frame at normal camera frame rates, you are going to miss most of the actual event. But, if you are lucky enough to get something in one of those frames, it would be fairly crisp without motion blur at 1/15000 of a second.

Hope this adds to the clarification process for you. I just wanted to add to the other excellent posts. Here's a link to a place you can get what you want for your scientific experiments.

-gb-

A. J. deLange February 15th, 2005 07:14 AM

Do a little math. With a hot varmint round at 2000 fps the bullet will move 2000/15000 = .133 feet or 1.6 inches during a frame and will be badly blurred. A pistol round at 500 fps would move a quarter that distance which is still almost half an inch - again badly blurred. Plus where are you going to get enough light for 1/15000 shutter speed? The answer to that question (and the solution to the blur problem) is a strobe light which emits very intense light for a very brief time (microsecond or less). Even though the shutter is "open" long enough for the bullet to move a substantial fraction of an inch the light is only on for a small subfraction of that time and the bullet appears frozen.

Next question - how far does the varmint round go between frames? Answer: 2000 fps/30 = 66.7 feet. You could shoot 60i in which case the two fields would show the bullet 33.3 feet apart if you were far enough back to cover 33 feet in which case you wouldn't be able to see the bullet.

A final question has to do with how you would sync your high speed strobe to the camera and the firing of the gun.

This has been done by amatuers with still cameras. The trick is to capture the firing event near the muzzle with a microphone or by having the bullet break a fine wire and set up the camera far enough down range that the delay in the triggering circuit is equal to the time of flight to the camera. I don't think the XL2 is the proper tool for this.

Obviously, extreme discipline and constant attention to safety considerations are paramount in an endeavor like this. I

Forbes Hansen February 15th, 2005 06:56 PM

oh dont get me wrong. We hae done the math but there are so many different things you can do with that camera i wasnt sure if it would be possible. Safety isnt a concern thoguh. You just set up the camera and move behind the gun, ect. I appreciate you input though. I dont think we will do it. Just to much.

Chris Staab February 18th, 2005 07:25 PM

It is possible to see the bullet.....
 
I have video of skeet shooting, and more often then not there is a frame with the spent round captured. I was pretty shocked when I reviewed the tape.

Roger Moore February 18th, 2005 10:37 PM

http://slashdot.org/article.pl?sid=04/12/28/2144252&tid=152&tid=126

"Researchers at Stanford have demonstrated multi-thousand frame-per-second (fps) video using a dense array of cheap 30fps CMOS image sensors. A benefit of using a camera array to capture high speed video is that we can scale to higher speeds by simply adding more cameras. Even at extremely high frame rates, our array architecture supports continuous streaming to disk from all of the cameras. Now we know where to use 100TB tape drives and what to expect in the next sci-fi movie."

Roger Moore February 18th, 2005 10:43 PM

http://www.photron.com/gallery/gallery.cfm?CFID=581503&CFTOKEN=58024231

Shotgun Blast into Mirror

Originally recorded for a Discovery Channel program, these images use a mirror to show high-speed buckshot fired from a shotgun. Both the buckshot and the powder charge can be clearly seen...at 1000fps.


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