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Slow motion questions. . . how to do it best for 4K?

Stephen Pruitt

Stephen Pruitt

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Hi all. . .

I want to put a few slow-motion (say, 1/3 speed) shots in my next film.

We are shooting the RED a 2:1 4K (my preferred format), but we're limited, of course to very low frame rates.

Are there ANY software slow-motion plugins that will give us the smoothness of 2K high speed (72 fps) but still shooting at 4K? I hate that stuttering frame, frame, frame look of 4K slowed down. . .

The trouble for me is that I'd like to have a 4K option for the film, as we think it may well have some legs, but when we shoot in 2K, we can tell a big difference between 2K and 4K even when viewed in 2K. I mean, no comparison. I suspect that shooting in 2K and then doing a 4K finish would be VERY obvious.

Naturally, we'd like to be using Epic. . . but that isn't an option just now.

:-(

One possibility, of course, would be to play with the color and make it very obvious that we were not aiming for the same look between the slo-mo and the regular speed, but that certain does limit our options.

Any suggestions?

Thanks.

Stephen
 
I'd much rather shoot 3K @ 60...

How the plugins works, is very dependent on the subject you're shooting, camera-movements etc etc, but I really dislike artificial slomo...

Just my 2c.
 
Hey there, Gunleik. . .

. . . how noticeable is the difference between 3K and 4K? I mean, does it stick out? Or do you really have to look for it?

Thanks.

Stephen
 
What is your deliverable?

If it is 1080/2k, I would say you'll have a hard and geeky time spotting it, but shoot RC36 to disk, RAM or 16GB CF.

You'll have to do a testshoot with a comparable image...

But 60 fps is pretty nice.

2k can be easily spotted, though, if you don't adjust a lot to get punchy contrast and don't need too much detail in the image. (remember all the "blackish" watery 120fps shots from way back then?)

If you're going to 4k delivery, I _guess_ that 3k 60 will be more pleasing than 4k 30 to 60 or 24 to 72.

But do short tests.

My bet is on 3k/60, though
 
Sounds great. . . really appreciate the advice!

Stephen
 
Jim mentioned once that the compression for slomo in R1 is harder than regular shots. @RC36 you have more data per image if you shoot 24 than if you shoot 30 fps - sorta. Makes sense.

Thus, lower compressionrates (36/42) becomes more important @ slomo than at regular speed.

I dunno what RC42 kan do at 3k 2:1...
 
Some testing on lenses can be useful too. Use only your very sharpest and try to light for their sharpest aperture. We've taken a lot of slowmotions last year and there was a pretty significant difference between several lenses.
 
Well. . . my camera won't do 3K 2:1 at anything other than RC28 with my REDDrive. Will yours do 36 and 42???

Also, when you are doing slo-mo work, do you keep the frame rate at 180 or intentionally induce more motion blur with a 360? I have only ever done one slo-mo shot in a film before, and we did that at 2K (about 80 fps).

Thanks!

Stephen
 
Yeah, I did know that, Julio. . . I was just curious if people actually liked the 360 degree look for slow motion because it instills so much motion blur.

Stephen
 
shoot 2k

shoot 2k

From all my years as working head projectionist at movie theaters I think you will be ok with 2k because 2k is what they put on film for theaters. Also a lot of movies now a days are shot 1080p and put on film and you never know it. In fact Most IMAX are digital now and they are shown on christie 2k projectors I varified this when I went to see inception in IMAX they had 2k Christie projectors showing on the IMAX screen and it looked great. So I think you will be fine shooting 2k
 
even the new TRON is shot 1080p and going to IMAX
 
Good to know all of this guys.

Thanks again!

Stephen
 
Sorry to not agree, but don't shoot 2k unless you know that the images will work in 2k. 2k very often looks quite distinguishable, even @ 720...

As I said, with high contrast, and not too much detail (hair is OK as long as the background is white/black/whatever) and there's high contrast, 2k can look great, but generally, it looks a lot worse.

But do relevant tests...
 
True about the 2k, but you'll want to be careful as 2k slowmo can look a lot softer than 2k deliverable that was shot as 3k or 4k. 3k is a lot more forgiving than 2k. But still, we have shot some slowmo in good light with a 50 mm lens at 2k 100 fps that had people say how sharp it looked. Testing a few lenses beforehand could be a good idea.
 
Martin Ubilluz said:
From all my years as working head projectionist at movie theaters I think you will be ok with 2k because 2k is what they put on film for theaters. Also a lot of movies now a days are shot 1080p and put on film and you never know it. In fact Most IMAX are digital now and they are shown on christie 2k projectors I varified this when I went to see inception in IMAX they had 2k Christie projectors showing on the IMAX screen and it looked great. So I think you will be fine shooting 2k
Click to expand...


When you shot 2K on a Red One's 4K sensor, you are shooting the center of the sensor and your glass. The results are your image is noticeably softer than at 4K and for critical focus is more difficult to attain. Personally I try to avoid 2K, 3K is a nice compromise though.
 
For an (admittedly older) example of post-slomo, see the paparazzi sequence at the very end of "Life Aquatic with Steve Zissou". Mostly looks OK, but with some tell-tale optical flow artifacts.

I think that's what you should expect from post slomo - mostly OK, unless you have a real whiz doing it (and I mean a real whiz).
 
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