How to record slo-mo with the ki pro mini and af100

T

TwinCitiesShooter

Active member
One of the few downsides to combining the Panasonic AF100 and the AJA Ki Pro Mini is that the AF100 only offers variable frame rates in 1080, while the Ki Pro Mini only captures variable frame rates in 720. So no slo-mo - supposedly. That's why I was excited to discover a workaround that allows for some very smooth slow motion footage. While shooting some tests, I realized that if you shoot 1080/24P 60 frames-per-second on the AF100 and record it via SDI on the Ki Pro Mini in its regular 1080/29.97 setting, then slow the footage to 50% speed on a Final Cut Pro timeline and render it, the result is about as smooth as native AF100 slow motion footage. There is little to no sign of frame interpolation - each frame looks like a clean, native frame. Note, it's best to drag footage into an empty timeline and let FCP choose the settings to match (e.g. frame rate, Upper Field Dominance, etc.). One wrong setting and it won't work.

One caveat - the final result is the equivalent of 48fps, not 60fps. The reason is that slowing 24P footage by 50% obviously gives you 48fps. Reduce the speed to 40% and now you've got 60fps footage - however, the footage then shows the artifacts we normally see in artificial slow-motion, namely frame interpolation and stuttery motion. So be happy with 48fps and remember this is only a temporary workaround - AJA has always planned on future firmware updates allowing for more variable frame rate options. I've contacted AJA about this happy find to ask how it is possible. The first tech I spoke with was unaware of this possibility, but he's passing it up the chain and hopefully we'll have a technical explanation soon.

Vimeo link: http://vimeo.com/23391767

Downloading from Vimeo is enabled, if you want to go frame by frame through the video.
 
Interesting Kevin. I'll have to look at the footage once I'm not on my phone and actually in front of my computer, as well as test it myself. What I've been doing for 60p footage and recording to the Nanoflash is record 720 60p and changing it in Cinema Tools to 24p.
 
You know the more I think about this, I would combine our methods and take the imported 1080 29.97 footage from the Ki Pro Mini and first send it thru Cinema Tools to get slightly slo-mo 23.98 footage and then slow it down in FCP 50%. I'd venture to guess you'd get even better results.
 
Yes - that works with the Ki Pro Mini too. And blowing it up to 1080 doesn't look bad, we're used to that with the HVX200. It's nice to shoot slo-mo in 1080 though, if 48fps is fast enough for the shot.
 
It was a good thought, but didn't work - it came out with severely interpolated frames. Unfounded hypothesis here, but it looks to me like when the AF100 is set to 1080 at 60fps, the Ki Pro Mini reads all the frames but doesn't know how to turn that into a 23.98 slo-mo shot (the way it can with a 720 shot at 60fps). So when you put the shot on an FCP timeline, it looks kind of like a normal 24P shot but with a fast shutter speed - the sharpness of all those frames is there. So when the speed is adjusted to 50%, it's clean. But with the Cinema Tools workflow, those extra frames are lost or muddled in the conversion and it doesn't come out right. It's definitely a quirk of the Ki Pro Mini, and I'm still waiting to hear back from them on what's really going on here. It bodes very well for a 1080 slo-mo firmware update, I think.
 
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