Slow-Motion ramps

[Thomas Buelens]

Hi fellow cinematographers,

 

I'm doing a shortfilm about three dudes who robe a nightshop.

 

At a certain point in the story the climax is reached when one of the guys step into the nightshop. I tend to travel begin the shot in 25fps and travel in, while going in slow-motion (125fps).

 

I wonderd if it would be better if I would just stay in the 125fps and speed up the beginnig in post, so the problems I will have with the lighting wild be fixed???

 

I shooting that scene on the Vision 500T 5218 stock.

 

If I do it ramping wise from 25fps, it will be a pain in the ass for these reasons right?:

 

-my camera-ass.: -focus puller starts @ maby, f 8.0 and goes to f 2.0

-iris must be opend while ramping from f 8.0 to f 2.0

-ramping remote from 25 fps to 125fps

 

Please, tell me my solution will work? I know the effect in the speed-up will be kind of sharper because filmed in 125 fps, but that's ok, because their focused on what they are doing, until they see something that tey didn't expect...that's where the slow-motion kicks in !

 

Thanx.

Thomas from Antwerp, Belgium.

[Rob van Gelder]

That will probably the slowest robbery ever, 5 times slower, enough for the cops to finish their coffee before the go to the store...... :P

 

1) Shooting on 125 fps gives you about 50 second of shooting time per roll.

You have probably planned the length of the action within this 0 seconds?

 

2) with a 435 and RCU and the Arri WirelessFollow Focus there is no problem at all to ramp and compensate for the exposure.

 

3) Ramping only when needed will give you more screentime.

 

4) The decreased dept of field on 125 fps might be interesting to focus more on the action.

 

5) Be sure to use only Tungsten based lighting or flicker free, no normal fluorescent unless you like the effect of flicker in the ramp up, might be interesting.

 

6) You have to light for 125 fps anyway, the extra equipment needed for a ramp up is little. I shot like this on my Steadicam with a 535b (ramp from 25 to 60 fps) heavy but possible.

 

Have fun, try it, in my opinion it is often better to make decisions on set than " solve it in post" !

 

Rob van Gelder, Bangkok, Thailand

[Mitch Gross]

Most camera manufacturers have a control box that will let you program the ramp. You set the start and end speeds and the duration for the speed change. Depending on the camera and box, the exposure is automatically compensated by the shutter angle or the lens aperture.

 

My problem in the past has been getting the speed change to happen at exactly the moment we want. If it is something that you want precise or will happen quite quickly, I'd reccomend simply shooting at 125fps all the time and pulling frames in post.

[Patrick Neary]

Hi-

 

I've also had problems with ramps (with a 435) where a slight exposure fluctuation happens at the initiation of speed change. I don't know how common that is- it's subtle, but it always bothered me because it "announces" the ramp.