Slo Mo Expert Needed

jlames

jlames

Well-known member
I've read so much from people who, through the content of their posts, exhibit clearly that they are experts in the use of Premiere, like Shooter and Overnightinlondon and yet slow motion seems to be an issue for everyone. Since I'll be incorporating a number of slo mo clips in my production, can anyone tell me how to get the best results incorporating tricks that perhaps aren't carried in the volumes of "Premeire Expert" books when it comes to creating slow motion? There was a definitive post done on the DVX and the HVX by moderators which cleard up alot of confusion for me and quite frankly made the difference in my selection between JVC or HVX. I know I'd appreciate a couple of paragraphs explaining why slo mo is so problematic and what we can do to over come this problem to the greatest degree possible from people who really know like Shooter and Overnight.
 
I'll give this a shot for what its worth. Hope I am not telling you too much what you prabably know but...

Slow motion is best "captured" by a camera running a higher frame rate than the projection or screening rate. eg Capture at 48 frames per second and screen at 24 frames per second. That means "realtime" is being captured twice in effect. Eg 1 second real time becomes 2 seconds screen time. ( A time stretch).

(96 fps woud be a 1 sec r/t :4 second screen time)

More frames captured means more increments of time and visual information is captured.

Film cameras manage this easily by altering the frame per second rate.( This has added advantages of increasing the shutter speed and producing a sharper image). Most vido cameras can not do this so resort to a "software solution" as does the NLE such as Premiere. The Varicam is an exception but I believe it is still a form of software manipulation to achieve the resulting slo mo.

The software solution is really a fudging of the frames that have been captured and making up some"tween" frames of what its got to work with. If the information is not avaialble or blurry (such as caught with shutter speeds too slow to catch the or freeze the movement) problems arise. No software can work with out the information available.

There is a software plug-in that does a very smart job of this (Twixtor 4). It aint that cheap but it does an amazing job of "tweening" the frames.It has sophisticated pixel tracking technology that works out where the pixels should go in the tween frames.

After Effects is also good at it but I believe the Twixtor plug in is better. Both can "ramp" the speed change over time.

Tip : Use highest possible shutter speeds for scenes intended as post production slo mo.

I find that PremPro can do reasonable job on simple frame rate changes and it pays to work in rounded figures. eg 50%, 25% etc

Conversely speed ups are easy for software. It just has to discard frames to compress time.

I do suspect that slo mo is more difficult for NTSCers than us PAL landers where the conversions are not complicated by the NTSC video standard and its various frame rate accomodations (fudges !)
 
Thnaks for the fantastic job of explaining. Unfortunately I decided in post to slo mo some pieces so I'll try both After Efx andf Twixor. Maybe they'll have it at DV Expo. BTW, I poined up the show special price of about 400 minus a 75.00 rebate for Serious Magic's Ultra yesterday at the Expo and wow was it worth it. I spent until 3 this morning playing around with it's going to cut production 'Tewaking time by 99%. I don't know if you've ever tried it but it really is unvbelievable. The 3 DVDs of virtual sets tacked on another $600 but we'll use them and again, WOW. Thanks so much for the slo mo info.
 
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