Slow Motion
 

A few people have shown interest in a discussion about ways to create slow motion. I will start this thread by explaining how I personally shoot slow motion with my XL2, then answering any questions people want to ask. Even if you have asked the question in another thread please ask it again here so we can start discussing it in one place. Thanx hope you guys enjoy.

Film in 60i. Pull that over to the computer as normal but be sure to use the scene detection option so that the clip is only 60i (kinda a duh but some people don’t know). Open After Effects and create a composition 2.5 times longer then the source file if u want ur final frame rate to be 23.976. If you want it to be 29.97 then set it 2 times longer. Then also set ur frame rate for the composition to whatever you want ur final frame rate to be (again kinda duh but I’m just going step by step).

http://i32.photobucket.com/albums/d1...low%20mo/1.jpg

Okay so now import your 60i footage. Right click on the footage in the project window and click on interpret footage. In the new window that has popped up under fields and pull down there is a place that says separate fields. If you are using HDV 60i then make sure it says upper field first. If you are using DV 60i make sure it says lower field first. Be sure to click “Preserve Edges”.

http://i32.photobucket.com/albums/d1...low%20mo/2.jpg

http://i32.photobucket.com/albums/d1...low%20mo/3.jpg

Basically what this has done for those of you that don’t know (there are some) is it has separated the fields and is treating the even fields as one frame and the odd fields as another frame. Preserve Edges tells it to interpolate the fields it isn’t using. But the clip is still to short so it isn’t showing all the frames it should.

Go up top to layer. Then click on time. Under time change the speed to 250% for 24p and 200% for 30p. If u have done everything correct you should be able to preview this and it will look like real slow motion. Export it and you are done.

http://i32.photobucket.com/albums/d1...low%20mo/5.jpg

http://i32.photobucket.com/albums/d1...low%20mo/4.jpg

This is how my man Robert Rodriguez did slow motion for Once Upon a Time in Mexico. The F950 were able to output 60p rather then 60i that the F900 did (if my memory serves me correct). Anyways hope this helps. Have fun.

(ADVANCE USER TIPS)
If u use HDV u can actually put that into a DV composition and not have to interpolate the lines u don’t have because each frame is 540 lines in a 480 line composition. But the color and gamma curve wont match the XL2 if that is what u are using to shoot ur progressive footage. I think also if u put a vertical directional bur of either 1 or 2 pixels it will smooth out the flicker.

Great info,
although I'm a PAL guy and have tried the 50i/seperate fields process but never got it to work...
you have any neat description on how to do the same with 50i`?
regards

I have never used PAL footage but theoretically the process should be exactly the same. Just change the numbers a bit. Make your comp 2 times longer, separate the fields the same way, time stretch, and export. If you can’t get it to work then put some 50i footage online so I can download it and play around with it. Make sure its not to long because I will need raw footage to make it work best.

Allan, thank you for the great info and starting the thread. Any thoughts on mixing 24pn footage with 60I (for the slow motion) and filters to perhaps match up the 60i footage to look close enough to the 24pn footage? I'm trying to avoid that total video look on my next project. It will be done for a Music video that will incorporate some slow motion shots.

Joe

I’m sorry but I don’t totally understand the question. If you film with a 1/120 shutter speed it will match up with 24p using a 1/48 shutter speed. The rule when shooting digital is use 2 times the shutter speed of the frame rate you are shooting at. If you shoot at 24 use a 1/48, if you shoot at 30 use a 1/60 and if you shoot at 60 use a 1/120. If every thing is the same with the camera (lens, gain, gamma curves, ext.) then it should all look the same. Can you be a little bit more specific about the “total video look” you are running into?

P.S. My name has only 1 L in it. (Alan)

I do humbly appologize for my mispelling your name.

What I was inferring to is, at least to my eye, when I record in 24p, it seems to just give the image a film like quality. I've had footage shot in 24p have some people question if I actually shot with film. To me, 60I just looks videoish. Great looking quality to say the least with the XL2. I still love how everything looks, no matter what frame rate I shoot with. Although I've only used 60I with the XL2 once since I've owned the camera. But I'll have to experiement with 60I. It could be I didn't have the shutter speed set correctly to 1/120.

No you are correct. 60i will always look like video. Not film. But 60p in a 24p sequence will look film like and be in slow motion. What I described above is how to get 60p out of 60i footage.

When talking about the “Film Look” some things you need to really discuss are shutter speed compared to the frame rate (which is 2 times more), Gamma curve (use the Cine curve), Depth of field (you cant really do much unless you get a mini 35 by P+S Technik), and dynamic range (this is how the camera reads light, this cant be changed without major modifications to the camera itself). 60i turned into 60p and rendered out at 24fps will look like slow motion film.

Do some quick tests of you doing fun slow motion stuff. The test I did was I jumped in the air and turned it into slow motion and it looked perfect. Aside from a few technical things that I couldn’t change (DOF, Dynamic Range) it looked just like slow motion film.

Hope this helps.

thanks alan, I'll try your recipe as soon as I get time to play with AE.

regards

Yes, indeed thank you:) Can't wait to experiment as well.

I'm glad this thread was started. In a few weeks I will be shooting a motorcycle race and I intend to shoot part of it in slow motion. This scene will be a small part for my documentary. I'm shooting the film in 24p and was never too sure what was the best way to shoot good slow motion footage.

As an experiment while still in 24p I brought the shutter speed up to 180 and 210. Was this a good idea? I was wondering what this would do?

If shooting in 50i, why not just pull out the timeline in Premiere Pro to fit the time required for the slow-motion? Any comments? Why is it necessary to use After Effects?

Scott that was a good idea but its still harder to turn 24 full frames into slow motion then turning 60 half frames into 60 full frames.

Steve Premiere uses frame blending to create slow motion effects. It will just blend the interlacing and it will look HORRIBLE, at least compared to the method stated above. Try it out both ways and compare them at 100% magnification and you will see what I mean.

Thanks, Alan, I'll try it both ways..... Steve

Haven't tried it in Premiere Pro, but Vegas handles slo-mo really well and gives great results very quickly.

Richard

Yeah Vegas is pretty good. It uses frame interpolation. Basically it will take two frames and figure out what comes in between them mathematically based off of how the pixels change. This is a very good way to make slow motion but its better to film in real slow motion then if you want it even slower slow it down with interpolation. The changes that happen between two frames of 24p footage is more then changes between two frames of 60p footage so the interpolation software will have an easier time accurately creating new frames for 60p then it will for 24p. Usually my rule is that I don’t making anything more then 2 times slower with interpolation. That is usually the point when quality drops because it has to create more then one new frame. So at 24p you only get 48 but at 60p you get 120 frames, way way more frames for not much more work.