slow motion~crisp image
Posted 13 May 2009 - 04:39 PM
Actually here's a better question... What is 10degrees equivalent to in seconds? 1/250? 1/500?
ie: knife through head of lettuce (96fps) beads of water with clear tack sharp edges.
Posted 13 May 2009 - 05:06 PM
Posted 13 May 2009 - 05:06 PM
what about 96fps or 150fps?
Is there a downlodable table out there I can refer to?
SLS 4 = 1440 degrees (try doing that with a film camera!)
SLS 2 = 720 degrees
1/24 = 360 degrees
1/48 = 180 degrees
1/96 = 90 degrees
1/192 = 45 degrees
1/384 = 22.5 degrees
1/768 = 11.25 degrees
Posted 13 May 2009 - 05:16 PM
Your reel was impressive. I loved the slow motion! I always imagined that you would have to change the shutter angle to achieve sharp edges for filmming anything in motion.
What kind of lighting do you use for slow motion?
Posted 13 May 2009 - 05:31 PM
Well the high frame rate does give you a fairly short exposure time just by being at 1000fps. 1000fps with a 180 degree shutter is a 1/2000th of a second exposure. This is enough to freeze most actions. Things like small water drops and to some extent pours can benefit from an even tighter shutter, like 90 or 45 degrees, but that just requires a TON more light.
Most of those shots were lit with 5k, 10k and 20k fresnels.
Posted 13 May 2009 - 05:41 PM
Changing the shutter angle changes the exposure and the amount of motion blur, but it does not change the speed at which the action is being recorded. At 24fps, if you set the shutter to 90deg, you've got half as much exposure, and half as much motion blur. 90degrees is 25% of 360degrees, so your exposure is 1/96th of a second (1/24 x .25). Again, the rate at which things move does not change, but the amount of blur and exposure does.
So if you combine the two, you're going to get slower motion, less motion blur, and much less exposure time. Shooting 120fps with a 45deg shutter, for instance, will give you 1/960th of a second exposure time (1/120 x .125). Everything will move at 1/5th its normal rate, and also have 1/4th its normal amount of motion blur. In order to work out what values you need, you've got to figure out how long the event takes place in real life, and how long you need it to last on screen. If it lasts half a second and you need it on screen for 2 seconds, then you need to shoot it 4x the normal rate. At very high speeds, the exposure time is so low that you're naturally going to have very little motion blur, but if you want the action to have less than its "natural" amount, you can reduce the shutter speed to make each frame more "crisp," and the overall motion choppy.
Obviously, though, you're going to need a pretty massive amount of light in order to shoot that. In my example of 120fps and a 45deg shutter, the exposure time of 1/960th of a second means you need 40x more light, which is over 5 stops. Better pull out the Softsuns or whatever.
Does that help?
Posted 13 May 2009 - 05:46 PM