View Full Version : Slow Motion help :(
2007 December 19th, 01:10
Im just wondering if you have a high shutter speed like 1/600 or more does this help with slow motion?, because I want to create perfect slow motion for a bunch of music videos im doing to kinda create that slow motion singing cause I'll play the audio faster on set (Slowing down by 50% or 25% in post) Im really confused about this so if someone would care to explain It would be such a help :) Thanks
2007 December 19th, 14:34
2007 December 19th, 16:20
The following comment is not directed to Ariki in person but really more of a general question/rant to anyone reading... I'm sorry for the tone... but I think it needs to be said:
I've always been confused about WHO THE HELL is it that's telling everyone that shutter speed equals framerate... This seems to be a global problem since everywhere from the states to where I am in sweden people has gotten it into their minds that this is a fact...
Every time I ask them that if that was the case, why aren't the tape being consumed in an insane rate and that the tapedecks sure are oddly quiet when recording at 8000fps full resolution while they sound like a dragracer when fast forwarding at 10X speed (remember... 8000fps would be 333 x the speed of 24fps) ... And also... Where do they see the "smooth slow motion playback"...
What's the answer I get?... They are more than likely to say "But that's what the teachers told us at class."
So there's clearly someone out there spreading this misinformation since everyone that thinks this is the case was told so by someone higher up...
So, for the last time:
SHUTTERSPEED IS NOT FRAMERATE!
On the other hand... YES when shooting at a higher framerate you would likely be using a higher shutterspeed. Just to simulate the same motion blur as if the camera was actually capturing the event slowed down. Which would translate to 1/120 for 60fps when shooting 60i and pulling apart the fields to get 60p... which would give a clip that's 2,5 the length of its full speed when playing back in 24 fps...
In PAL country it would be 1/100 shutterspeed for 50fps interlaced footage which you pull apart to 50p and then play back at 25fps giving a double length clip.
That's how far into slow mo you can go with the HV20 without framestepping, frame-blending, or morphing between frames. 40% speed for NTSC's 60i to 24p, or 50% for PAL's 50i to 25p... THAT'S IT! the math is easy enough.
Spread the word... Let's beat this counter-intelligence agency in the war of facts about the shutter speeds influence on slow motion!
Now... I do apologize for the loudness and crudeness of my post, but one can only hear a missunderstanding for so long without snapping....
2007 December 19th, 18:09
(Not you Ariki...I'm just agreeing)
2007 December 19th, 18:22
Ariki....just shoot..60i (or 50i if you are PAL) at 1/100 shutter speed (since HV20 does not have 1/120) with the music sped up...let's say 50%.
In post just put the footage on your timeline and slow it back down 50%...sync it up with you .wav file and you have an option here...:
1. render that file to 60p file then put that back on a 24p timeline, edit and render to 24p...(not really necessary)....or
2. Render that file to 24p or 30p...it's all up to what you want.
You do NOT want to use shutter speeds over 1/250 for smooth slow mo. You can try 1/250 but 1/100 will be smoother motion
2007 December 19th, 20:54
It's true the shutter speed is not even close to the same thing as frame rate. But on film cameras, the two are definitely related based simply on how the shutter works. The shutter is mechanically linked to the film transport. The longest practical shutter is about 180 deg. The shortest any camera supports is about 35 deg. But the point is, the effective "shutter speed" will always be a side effect of the frame rate one runs a film camera at. Of course, none of this has anything to do with digital cameras what so ever.
Maybe the people you are ranting about are coming from some kind of naive "film land" understanding... you know... "a little knowledge is a dangerous thing" type of back ground. They got it in thier head that maybe all film cameras are a fixed 180 deg shutter and that changing the shutter speed (in some leap of "little knowlege" logic) makes the frame rate somehow change. (in fact, it's the other way around. It's changeing the FRAME RATE in that case that changes the SHUTTER SPEED)
Actually, I don't know how any one could come to the wrong conclusion here because no matter how you look at it the "wrong thinking" is totally backwards... but anyway... "a little knowledge is a dangerous thing" seems to be the best theory.
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