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Understanding Slow Motion & Hi Speed Video Capture Basics


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#1 Marcus Phipps

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Posted 16 October 2009 - 09:58 PM

This is my fourth newbie post.

I want to learn how to get that super slow-mo effect. Most often observed a flower blooming. Or a sunset going down. Or a sunrise. Or a bee flapping it's wings.

1) I am to understand this is accomplished in CCD at 1/1000 setting. Is that correct?
2) What happens if you capture it at 1/2000 setting?
3) What settings on the camera needs to be set to accomplish this?


If you are able to elaborate further, it is appreciated!



Most Respectfully,
Acastle
:rolleyes:

Edited by A Castle, 16 October 2009 - 09:59 PM.

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#2 Chris Bowman

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Posted 17 October 2009 - 08:53 AM

What you are talking about here is really 2 different things. A flower blooming or a sunset going down are usually time-lapse (greatly speeded up), while a bee's wings would have to be extreme slow motion. These are actually opposite effects.

Time lapse is accomplished by recording at a very slow rate, perhaps one frame per second, or maybe only one frame per minute. The CCD will still be set for a very short exposure (say 1/60 for video or 1/48 for film) in order to prevent motion blur.

The recording is then played back at normal speed, showing an event that happened over the course of hours in a few seconds.

Slow motion works exactly the other way around. Images are recorded at very high frame rates (up to 1000 frames per second) and then played back at normal speed, so that something that took only a second or two can be shown very slowly over a minute or more. Higher speed exposure leaves less time for the image sensor or film to gather light, which means that very intense lighting is necessary in order to produce a bright enough image at very high speed recording.

What you seem to be talking about in your post is shutter speed. Shutter speed, whether on a CCD or film, controls the amount of light gathered for each image, and the amount of motion blur. Longer exposures allow more light, but also increase blur, because more motion can occur while the exposure is happening.

Shutter speed is actually independent from the frame rate, especially in video. Film usually has a frame rate of 24 frames per second, and a 180 degree shutter (motion picture cameras have circular spinning shutters). This gives the camera time to advance the film to the next frame before exposing it and prevents unwatchable motion blurring. It also effectively gives normal speed filming a 1/48 second shutter speed.

Video has no mechanical linkages to worry about, allowing the shutter to run at any speed you want. My Canon XH-A1 will allow me to shoot at shutter speeds of 1/4 second (very bright, blurry, surreal). It can also expose as each frame as short as 1/2000 second (basically no motion blur, but requires huge amounts of light).

So basically, in order to shoot time lapse, set the camera to a very slow frame rate and a normal shutter speed. In order to shoot slow motion, set the camera to a high frame rate and a fast shutter speed.
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#3 Chris Bowman

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Posted 17 October 2009 - 09:09 AM

It should also be noted that not every camera has the capability to shoot time lapse or slow motion. Time lapse can be cheated by starting and stopping the camera every few minutes, then extracting just one frame from each of your many recording sessions for your final product. (This is, of course, very tedious)

Slow-mo is another story. If you are planning to show your product at 30 frames per second (Progressive scan) and your camera tops out at 60 frames per second (Progressive scan), than the best you can do is show a 1/2 speed slow down. If you can't use progressive scan, your slow-mo will have very poor quality, because slowing down interlace results in your perceiving a 50% decrease in resolution.

Edited by Chris Bowman, 17 October 2009 - 09:09 AM.

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#4 Marcus Phipps

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Posted 17 October 2009 - 05:46 PM

Chris,... thank you, sir! As always you're a fantastic resource of knowledge. I see several of my posts get viewed but not very many replies. But that should be considered a good thing once the question(s) are answered. :P

So let me be sure I understand what you're saying,...

First, I was an idiot in my original question(s). Yes, it's obvious I had two conflicting processes and was confused at my own question. Slow motion (plus super-slow-motion) and time lapse processes. Sorry about that. I am learning as I go.

1) Time Lapse = Example of sunrise / sunset and is accomplished by a snapshot every so-many-minutes. Which is a feature on each particular camera if that feature is even an option. Depending on your camera make / model. However, many modern cameras in the last ten years have the 'Time Lapse' feature.

Time Lapse
= Can be accomplished manually if a camera does not have such a feature by simply turning the digital still or video camera on / off so as to get only one frame. Which can be used in your 'series' of still images that makes up the sunrise or sunset. I am also reminded of the old cartoon flip-books. As you quickly page thru the pages, what seems to be a single image actually is merely a frame in a series of movements. Thus, flipping thru that flip-book causes the animation. Performing this on a digital camera is the same process of merely capturing a single image and later putting it into the series that creates the animation or movement you desire.

2) Slow Motion = The opposite effect and instead of slowing down the number of images captured, you are capturing an extremely large number of images / frames. This allows a fast moving object to be seen more clearly. Often used for sometimes unseen events / happenings. Such as how a football player is inbounds or out of bounds. The slow motion viewing allows the viewers to see what really happened. Was he / she in bounds or out of bounds? The slow motion video is a tool used in most sporting events / boards. Our naked eye may not see all things. Or perceive things different than the person next to us.

Slow Motion = Is not able to be created manually in video. It requires a camera capable of slow motion image capturing. Which most cameras in the last 15 years seem to have. Certainly in the last 10 years. This is not taking into account the 'Matrix-Effect' with multiple cameras and that whole animation process. Which is a separate post eventually. This definition is merely the basics at a comprehensible level of most us newbies.

Super Slow Motion = An example of this would be the bullet being fired from a gun. Or a hummingbird flapping it's wings. Something that is super-intense in motion. Something we can not see with the naked eye. And if we can, it's merely a few images or frames we see. But not the entire process. Super Slow Motion is best described as this bird or bullet and is frequently used in scientific experiments and television documentaries on how things work. At this point I do not have shutter speeds, frame rates, aperture settings, etc.

3) Shutter Speed = The amount of light that is absorbed into the capture. It also is relative to how much blur that occurs in each image. The longer the shutter / exposure is open the more the light is captured. However, the longer the exposure / shutter is open,... the more blur or susceptible your image(s) are to being blurred.

SUMMARY :

Time Lapse = You should set your camera to a normal frame rate / shutter speed. Moderate light is fine.
Slow Motion = You should set your camera on a high frame rate / shutter speed. More light required.
Super Slow Motion = You should buy a new 'non' newbie camera. he he - Anyone care to give some basics on super-slow-mo? I believe my hummingbird and bullet and Matrix references are probably pretty true as examples. But, more-so what feature(s) a camera or equipment or software is required. Or the basic process for the newbie mind to understand such term.



Most Respectfully
Marcus


PS - I took what Chris has offered combined with other things i've read online and put them together. Thus, the above delivers pretty well start to finish. Chris, or others, if you care to chime in if something is stated incorrectly. This is merely my attempt at documenting a newbie learning the basics. I am prone to mistakes or misinterpretations of what I am reading and then trying to convey.

Edited by Marcus Phipps, 17 October 2009 - 05:51 PM.

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#5 Chris Bowman

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Posted 18 October 2009 - 12:21 AM

Mostly right, but I would like to clarify a few points.

Your time lapse explanation seems pretty sound.

Slow-Motion is NOT available on most cameras in the consumer and semi-pro range. It is a feature that is largely preserved for professional cameras, like the VariCam. Some consumer and semi-pro cameras can achieve a limited slow-mo performance, but most are extremely limited.

Super slow motion can be shot at frame rates up to 1,000,000 frames per second, but this is entirely reserved to the realm of specialty cameras. If you need to shoot Super Slow Motion, you would almost certainly rent the camera from a specialty equipment facility, since purchasing one outright is not cost effective unless your job is analyzing bullet impacts or car crash tests.

As a point of interest, the NFL shoots it's games at 120 frames per second in order to achieve the slow motion effect so commonly seen on its productions. It does this with both its video cameras and its 16mm film cameras (that's a lot of film!)

Once the footage is captured, it is loaded into an editing program. Most editing programs have an "interpret footage" feature which allows you to tell the system the frame rate that you want the footage to play back at. Once this is set to the normal playback speed for the project (say 60 frames per second for NTSC) the effect is achieved.
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#6 Chris Millar

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Posted 18 October 2009 - 01:17 AM

As a point of interest, the NFL shoots it's games at 120 frames per second in order to achieve the slow motion effect so commonly seen on its productions. It does this with both its video cameras and its 16mm film cameras (that's a lot of film!)


In trying to avoid confusion you should note you use as much film as you use - 1 frame = 1 frame ...

Its no more or less film than at any other speed.
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