A question about slow motion

eqwalker

eqwalker

Active member
I have just recently purchased an AF100 and will be shooting a short at the end of the month. It will be shot in 24p but there will be a scene where I will want to capture a glass falling and crashing into the floor at a higher frame rate so it will be shown in slow motion breaking on the floor. Please excuse my lack of knowledge (and I did do a search on this) but my question is what frame rate would you suggest running at to give a good slow effect and how do you go about running the higher frame rate even though you are shooting the rest of the short at 24p? I have never done variable frame rates before so I am at a loss as to how to proceed and will anything in post need to be done? I don't have the AF100 yet (it is on it's way) so I am trying to gather as much information before hand to speed up getting familiar with the camera for the shoot.

PS: I will be using a Samuari for capture if that makes any difference.
 
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I've not used a samuari so someone chime in if I'm wrong, But I don't believe you can record variable frame rates externally. Using variable frame rates on the AF is very simple, just put it in VF mode and use the dial on the back to choose your frame rate. For the shot you describe, I'd suggest shooting at 60 (that's the highest the af will shoot) and use a high shutterspeed like 1/500. Then you can use your software of choice to slow it down further (motion, after effects, twixtor, etc)
 
You can't shoot slow-mo with the Samurai, so remove that from the equation. Your slow-mo shots will be shot on the AF100's native recording, to the SDHC card. Use a Class 10 card, turn on VFR, shoot in 1080/24p mode and set your frame rate to 48 or higher; for the slowest slow-mo, use 60fps. I would recommend a shutter of 1/120, unless you want an exaggeratedly crisp motion rendition, in which case you could use a higher shutter speed.

Nothing needs to be done in post; when you import the clip it will automatically be in slow-mo.

Note, no sound will be recorded when you record slow-mo.
 
Adamsenoj said:
I thought the "standard" for 60p was 1/60?
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If there's a standard shutter speed I'd say it's double the frame rate under 1. Thus at 24p the standard is 1/48th at 30 it's 1/60th and at 60 it's 120th. This is derived from the film camera days where most cameras employed a 180 degree shutter that closed while the film advanced to the next frame. But these days, i'd say there's not really a standard, it's more a personal preference on how the shot looks at different shutter speeds.

I suggested a high shutter speed for this shot because glass that is falling and breaking is going to be moving pretty quick and if you want to reduce the speed further in post then it is advantageous to reduce motion blur.

Personally, I prefer to shoot 60p at about 1/120-1/200, unless it's sports or fast moving objects, in those instances i'll reduce the shutter speed further to 1/500 or more. YMMV
 
Adamsenoj said:
I thought the "standard" for 60p was 1/60?
Click to expand...
The standard for live video shooting is indeed 1/60 for 720/60p (or 1080/60p, or 1080/60i, or, for that matter, 480/60i).

But for film-looking footage, as tacotim says, the standard is 1/(2xframerate), so 1/48 for 24p, 1/60 for 30p, 1/120 for 60fps.
 
@the op

dont expect the slo mo from the AF100 to really capture the fsallen, breaking glass in a spectacular fashion. Its just not fast enough. (Do a test when you can)

In post you can enhance it withthe Twixtor plug in - (expensive) or yuor NLE speedwarp will help it to a degree.

Best result for your subjectwould be a frame rate over 200fps... and done in camera
 
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