Slow motion at 3k - how?

[Clayton Taylor]

Looking for some help - Im going to start trying to figure out how to pull off slow-motion for a scene in an upcoming short Im shooting. I DO have Twixtor, but this is all new to me so I need to learn how to use it.
So question - I want 3k to make it easier to match the 4k footage from the rest of the film. I know 48fps is the max frame rate that I can get - so what shutterspeed do I need to use to be able to get a decent slo-mo? I understand perfect slow-motion comes with the Epic, not Scarlet - but Scarlet is all I can afford. Again, I have Twixtor if this will make it possible/easier.

 

[Mike Garrick]

48 fps is fine and looks good. Shutter speed, times it by x2 ie. 48 x 2 = 96.

Imo. 48fps can look sweet and no need for twixtor.

 

[Daniel Pearson]

If you're shooting for a 2.4:1 aspect ratio I believe the Scarlet can do 60fps in 3k, which is a decent bit faster than 48.

 

[Clayton Taylor]

We're looking to stay 16:9 or maybe 1.85:1

 

[Michael Tiemann]

I have a SCARLET DRAGON, so some of this may be helpful, some of it may not.

In general, you need to find the right recipe that balances: frame rate, shutter speed/angle, resolution, and compression. And you need to know how the raw product (pun intended) can then feed your post workflow (i.e., Twixtor) to get all the way to where you want to go.

If you are slowing down high-speed action (i.e., a humming bird or a bumble bee) then you can get away with higher compression ratios because the still-fast motion will sufficiently trick the eyes into believing that the resolution is there. If you are slowing down normal speed to slo-mo (such as a person walking or casting a glance at the camera), then the eye is going to be much more discerning about the compression artifacts it sees. You may well find that the 12:1 ratio that worked for motion doesn't work for slo-mo until it is at 8:1 or 6:1. Which forces some resolution tradeoffs.

Similarly, different types of action work best with 180 degree shutter angles (same as "normal" motion) and some work best with 90 degree or less angles. I just recently did the ALS ice-bucket challenge with my wife using an EPIC DRAGON (http://youtu.be/tPJawplKxsY?t=34s). I shot vertically at 2.5K WS 237fps at 1/500th of a second (very close to 180) and 8:1 compression. If I had to do it over again, I'd have shot at a higher frame rate (300fps, compression be damned!) and a much higher shutter speed (1/2000th of a second), because I really wanted to see the water droplets freeze when I slowed things down from normal speed to zero speed. At 1/500th, the water droplets were blurry as I cranked the frame rate down to zero.

Now, Twixtor may do some things better with a bit more motion blur baked in, or it might do best with as little blur as possible on the input (adding its own blur for the output). Based on my small but growing base of experience in slo-mo, I'm inclined to recommend cutting the shutter angle so that it's no more than 180 when multiplied by the max slowdown you present. Thus, if you shoot 60fps (2.5x slow-down) and Twixtor down another 2:1 (for a total of 5x slow-down), the shutter angle should be at most 36 degrees.

While the specifics of SCARLET vs. SCARLET DRAGON will dictate how far you can go in the frame rate/compression/resolution dimensions, the other factors discussed above should help you make better sense of the tradeoffs across those dimensions (with shutter angle and post tools as additional considerations).

 

[PJ Porter]

We're looking to stay 16:9 or maybe 1.85:1

If you are looking to stay in 16:9 (48fps) The safest shutter angles are either 144 or 288. I would try those out with the MX. I have twixtor also but I've never used it at 48fps, I would test these angles out and see what you will get out of both.

 

[Clayton Taylor]

Thanks guys. The tips really help. It's not a high speed shot - it's a close up of someone's face, so not much changing in the way of background either.

 

[Justin Batchelor]

I always shoot 16x9 3k with a frame rate of 48 and the project setting at 23.98. Cant' remember where I read that but it's working out so far.

1/100th at 2.8. Non conformed lens at 200mm so couldn't change the aperture. Got the shot though.