Disgraceful newbie question on Slo mo

Hi Guys,

If I shoot at 60P and put it in a 24p timeline, I can slow it down to 40%. If I play it at 100% you get that weird metallic 60p type motion. If I slow it down to 60% or 70%, am I right in thinking that it will be quite jerky?

So the only way you get really smooth slow mo on 60p is when you slow it all the way down?

If yes, am I right in thinking that you use optical flow to make a 60p clip slowed to 70% look smoother??

Thanks in advance !
Phil

1- Drop 24fps clip into a 60fps timeline.
2- Select that clip, go to the Speed menu, select "Automatic Speed"

This uses all of the clip's original frames, speed out, to give you true "in-camera" slow motion. Since there's no frames being created from scratch as in other scenarios, that's about all you have to do, since you're using all original frame, nothing gets filled in (faked).

If you wanted to slow it down more, I'd go a little more, not get drastic, and THEN apply Optical Flow as the Video Quality.

If I wanted to slow it by 70%, so not the complete 40%... would it be jerky?

IF all you did was slow it down by 70%, yes. But if you changed the video quality to Frame Blending or Optical Flow, it would be less so. Optical Flow's efficiency will depend on the clip's content. Moving backgrounds in an image usually warp. Try it, experiment, see what happens.

phil@circuitfactory.ae wrote: …So the only way you get really smooth slow mo on 60p is when you slow it all the way down<?…

aside 'cadences' = how to divide 60frames onto a 24fps timeline, another important point is Motion Blur, made by slow shutter speeds … unfortunately Optical Flow works best with crystal sharp frames, smoothness on contrary asks for as much 'smear' as possible.

So, I would suggest to play with shutter speeds too, could ask for NDfilters and such …

It depends much on content - in case the 'delta'/difference btw frame#1 and frame#2 is too big, OF creates erratic wobble. And, using slowmo for my football/soccer stuff, I noticed, OF has trouble with rotational movements (rolling ball, tires on a bike, car…)

Finally, all those super-impressive demoes of computational slow-mo (twixtor) take place in front of static, single-coloured backgrounds (skateboarders in the sky…) - in case, your background is trees in wind, a partying crowd - OF et al fail....

last word: nothing beats real frame rates … :lol:

Karsten Schlüter wrote: ... aside 'cadences' = how to divide 60frames onto a 24fps timeline, another important point is Motion Blur, made by slow shutter speeds … unfortunately Optical Flow works best with crystal sharp frames, smoothness on contrary asks for as much 'smear' as possible.:

As a side note, I just saw a tutorial for AAE, in which someone shot RAW stills in burst mode @12 fps, excluded motion blur by using very short exposure times, developed in CameraRaw, stabilized with Warp Stabilizer and made really impressive 20 x slomos with different amounts of motion blur added in post.

This is insane, but the results can look stunning. For obvious reasons, this is not suitable for sports or moving camera or the notorious wet dog slomos. But if you know how to do it, you can stretch ordinary 23,98 video endlessly with optical flow.

Axel wrote: … with different amounts of motion blur added in post.

<cough> not exactly as beautiful with that indeed insane workflow (12fps to slow mo??), but avail as a free plugin
www.fcp.co/forum/film-looks-effects/2563...-to-add-blur-in-fcpx

… which blurs any motion in the frame in post either

Axel wrote: ……if you know how to do it, you can stretch ordinary 23,98 video endlessly with optical flow.

I'm not shy to frequently post my lil' test, recorded with 100fps (Lumix FZ1000), and 10% speed + OF in FCPX:


… can not find my other example, with computational '5000fps' (=2%)
(YT's search feature is a pest!)

Superslowmos are easier than 'uneven' slow mo such as 48% or 90.5% or…

The thing with different frame rate video, and or slow and fast motion, is that for best results the frames should be evenly divided. While slowing it down all the way is one way to do that, you can also do every other frame or even every third frame, which would be 80% and 120% speed for your case, so you could try that and see if you like what you get.

Otherwise, what everyone else has said about optical flow, etc... is your best bet.