how much light does slo-mo need

[Joe Batt]

Hey guys, I'm considering this camera. (between this and the C-100) Does this camera need a significant amount of light to get a good looking slow-mo image?

[Chris Medico]

If you are going to shoot 240fps versus 24fps you will need 3-4 stops more exposure for the slow-mo stuff. Shooting outdoors during the day isn't a problem at all.

[James Barbosa]

Lots of light.

[Chris Medico]

Lots meaning 3-4 stops more over standard 24fps settings. That does assume a 360 degree shutter when shooting 240fps. If you jump to 1/500 on the shutter then it becomes 4-5 stops.

[Tim Dashwood]

If you normally shoot with a 1/60th shutter exposure then by default shutter settings (360 degrees) 120fps needs twice as much light (1 stop) and 240fps needs 4 times as much (2 stops).
If you normally shoot with 1/48th shutter exposure then 120fps requires 2.5 times as much light (approx 1 and 1/3 stops) and 240fps requires 5 times as much light (approx 2 and 1/3 stops)

[Joe Batt]

Thanks everybody!

[Tom Gresham]

We just shot at 240fps with night vision. Very cool!

[Nils Dumortier]

I'm planning on buying the fs700 but before I do that, I want to take it out on rent for some tests.

One of the projects I have in mind is a snowboard and ski event. Kinda cliché but it seemed like an ideal opportunity to test those high frame rates. It's an indoor event however. So light will probably cause problems.

Guess I could get rid of some flicker in post with CC time blend, that's not my main concern. I just saw a video of a previous edition on the same location and it really seems dark in there.

What do you guys think?

Antwerp Ski and Snowboard Railbattle - YouTube

(not my video)

Would it be possible to do some slo-mo there? I would be using Zeiss CP2's (18mm/T3,6; 50mm/T2,1; 85mm/T2,1).

Thanks!

[Colin Elves]

What sort of mount do the CP2s have? If they have Canon EF mount, then you can use them with the metabones speed booster (apart from the 18mm, which I think will crop the edges a bit) and get an extra stop out of them.

On top of that you can shoot at higher ISOs - up to 3200 I've found is fine with the FS700, with no appreacable increase in noise (relative to the extra noise you get shooting slowmo anyway).

Beware you'll get extra aliasing when shooting slowmo as well - becuase of the way the chip works in slowmo.

[Colin Elves]

Also that reference video doesn't make it look like the place is especially dark.

I think the people that shot it a) had crappy lenses (it looks like the shot of the 550D had an aperture of f6.3) b) didn't know how to expose and white balance properly (the snow was yellow) and c) they gave it a crappy grade with a dodgy vignette. In other words, you can't really tell what the lighting conditions were like there.

[Nils Dumortier]

Thanks, Colin!

The CP2's have PL mount, so no speedbooster for now, but that's the first thing I'll get when I buy the FS700.

I think l will just give it a shot. The rental period is four days, so I'll have plenty of time to experiment.

[Eric Darling]

Just FYI, CP2 lenses have interchangeable mounts. If you're renting, perhaps they can swap them out for you...

[Colin Elves]

Yeah, they're supposed to have universal mounts, so you could ask for them to be changed, or see if they have a set of Canon CN-E cinema lenses as an alternate - they're all full frame and faster than the CPs as I recall.

[Dmitri Zigany]

Does the FS700 have a way to automatically boost gain as it goes into super slow motion recording?

[Cees van Kempen]

You better try to avoid using gain in slomo. It is okay to use gain in normal frame rates, but in slomo the footage becomes noisy much sooner. At 0 gain the picture is pretty clean, but even then the camera is not as clean as in normal shooting mode.