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#1 Varun Nayar

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Posted 07 July 2006 - 09:04 AM

Hi,

I am a first time poster (please dont bully on me). I am into wildlife filming and am currently under training. My question is on the different Shutter rates of mini DV camera's. I know there are other posts in the same topic. I searched. Everything soon goes on to shutter angle and frame rates.

I wanna ask is this: You can increase the shutter speed in PD 170 Pal to 1/10000. Does this actually affect the fottage in post production. For example: I shot a tea garden from a moving car. I shot it in 1/50 shutter speed. When in post production my trainer wished to slow mo it and said you should have picked a faster shutter speed like 1/1000 or so. Or it would come out all interlaced and dirty looking ;) .

I often use this option to control the aperture. When I want very low dof i increase shutter speed, so i can get a lower aperture. But did not strike to me it could be used for slowing down motion.

(Please dont confuse me with shutter angle and frame rates since I don't think the PD has these options).

Any reply would be appretiated.......Thank you so much (those who have posted below).....
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#2 David Mullen ASC

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Posted 07 July 2006 - 11:40 AM

(Please dont confuse me with shutter angle and frame rates since I don't think the PD has these options).


I will confuse you for a moment -- when a film camera overcranks at faster frame rates for a slow-motion effect, the shutter speed naturally gets shorter. Since a standard 180 degree film shutter is closed 50% of the time, at 24 fps, the shutter speed is 1/48th but at 200 fps, it would be 1/400th. So the amount of blur per frame is determined by the shutter speed.

So if you are shooting video at 1/50th, let's say, and you stretch it out to be slo-mo in post, your amount of motion blur per frame hasn't changed, so slowed-down, it now looks too smeary. You have to use shorter shutter speeds to get less blur per frame so it looks correct when slowed-down.

Using the shorter shutter speeds doesn't affect the recording other than the amount of blur per frame/field. But then you are stuck with it -- it won't look normal until you slow down the footage, so you have to decide up front whether the shots will be slow motion to some degree. Normal speed footage shot with a short shutter speed will look strobey because now you don't have enough motion blur per frame.

I suppose since you are shooting interlaced-scan, you could split the difference and use 1/100th now & then if you think it might get slowed down a little in post. It will be a little strobier than 1/50th if you end up not slowing it down, but it may be acceptable.
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#3 Peter J DeCrescenzo

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Posted 07 July 2006 - 11:59 AM

... You can increase the shutter speed in PD 170 Pal to 1/10000. Does this actually affect the fottage in post production. For example: I shot a tea garden from a moving car. I shot it in 1/50 shutter speed. When in post production my trainer wished to slow mo it and said you should have picked a faster shutter speed like 1/1000 or so. Or it would come out all interlaced and dirty looking ;) ...

I believe it depends not only on which editing or other software you use to achieve the slow motion effect, but also on which version (how recent) the software is.

For example, I worked at Macromedia several years ago where Final Cut Pro was originally developed (it was know as "Key Grip" then, and later purchased & renamed by Apple). Back then, I was told that KG/FCP's slow motion feature was designed/optimized for NTSC video shot with a 1/60th sec. shutter -- in other words, this shutter speed would produce the smoothest-looking slo-mo.

That was a long time ago, and FCP has changed enormously since then. Plus, there are now several other software editing and post-processing apps in use. As a result, it's possible there is more than one "correct" answer to your question.

The best way to determine the answer to your question might be for you to shoot some simple tests to see which setting produces the best or most pleasing slo-mo result using your cam and software.

For example, you might put your cam on a tripod, lock it up, and have it record a few seconds of the constant motion of something mechanical, preferrably something which always moves at the same rate of speed, rotation or so forth. For example, a slowly-rotating phonograph turntable, or a slow electric fan.

Use your cam to record one test clip using a 1/60th shutter (and/or 1/50th if it's a PAL cam), and several other clips using other shutter speeds. Then capture the video into your editing software and apply its slo-mo effect.

Let us know about the results you obtained, and which software and version you used.
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#4 Daniel Sheehy

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Posted 08 July 2006 - 03:36 AM

Hi,

Probably the best thing to do is to go out & shoot test footage at various shutter speeds and play with them in post.
As Mr DeCrescenzo noted, moving subjects would be best.
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#5 Varun Nayar

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Posted 08 July 2006 - 09:00 AM

wow....not only did I get my doubts cleared but I just understood the connection with film cameras. And gave me ideas for post too.....THIS SURE IS A GREAT PLACE.

:( the only problem is, the only time the camera is allowed out is when we go for shoots. So I cant actually make a test until the next shoot some two weeks from now. What I will do is this, if I see a water fall, I will record a static shot of 20 sec each in 1/50th and 1/200 or 1/100th. That would be interesting.... :lol:

(Thank you so much david, peter and daniel)....
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