I'm going to be shooting some sports this summer (water skiing), They say to use a shutter speed of double the frame rate. I plan on using a few of my good shots for slow motion effects in post, so thought I'd like to use a high frame rate of 120 fps, so that means shutter at 1/240th. However once I finish editing, the final production will be rendered at 30 fps. So I guess my question is, should my shutter speed match my shooting frame rate, or my rendered frame rate, and why ?

Frame rate, although you don't need to be exact.  I have shot 30p at 50 and 80fps.  Your 120 doesn't have to be exactly 240.

parkgt214 Posted at 6-19 06:08
Frame rate, although you don't need to be exact.  I have shot 30p at 50 and 80fps.  Your 120 doesn't have to be exactly 240.

But you didn't really answer my question. Is it best to choose a shutter speed that only creates enough motion blur for my shooting frame rate, or enough for my final rendered frame rate. I believe a videography expert would say to match the shooting frame rate. But I don't understand, as the viewer will be watching the final render ar 30 fps.

Hi, thanks for the inquiry. We're hoping that you could get the best recommendation that you may need in regards to your query. Thank you for your support.

TrevorSK Posted at 6-19 07:52
But you didn't really answer my question. Is it best to choose a shutter speed that only creates enough motion blur for my shooting frame rate, or enough for my final rendered frame rate. I believe a videography expert would say to match the shooting frame rate. But I don't understand, as the viewer will be watching the final render ar 30 fps.

You're confusing shutter speed and frame rate.

Ideally you should shoot videos in manual mode, ideally at ISO 100 (because higher ISO's on DJI drones is woeful) and set your shutter speed at double the inverse of your recording frame rate. So if you're shooting at 4K 30P (30FPS), you should set your shutter at 1/60s and use an ND filter and/or aperture to adjust your exposure levels. If you're shooting sports and using a higher frame rate, say 60P (60 FPS), set your shutter speed at 1/120s. At 120P (120 FPS), use 1/250s.

The idea being that the 2 frames being interleaved into the video will provide a much smoother effect. You see guys on here posting videos using auto mode and they might be using a shutter speed of 1/1000s @ 30P and their videos look all jerky because the video is skipping frames and attempting to interleave odd frames into the video.

Watch some youtube videos on it and you'll understand why this is important for smooth videos. Search for "video shutter speed frame rate" or something like that and you should get a load of hits.

gyrex Posted at 6-23 06:24
You're confusing shutter speed and frame rate.

Ideally you should shoot videos in manual mode, ideally at ISO 100 (because higher ISO's on DJI drones is woeful) and set your shutter speed at double the inverse of your recording frame rate. So if you're shooting at 4K 30P (30FPS), you should set your shutter at 1/60s and use an ND filter and/or aperture to adjust your exposure levels. If you're shooting sports and using a higher frame rate, say 60P (60 FPS), set your shutter speed at 1/120s. At 120P (120 FPS), use 1/250s.

Yes, all fine and dandy when you shoot in 30fps, set your shutter to 1/60th, render the final video in a 30fps format, and bobs your uncle...  But my conundrum is, I want to shoot at 120fps, and render down to 30fps in Final Cut Pro. I have to assume the software will just discard 75% of the frames.

Maybe I can ask this question: How do the sports networks shoot? I know my cable company provides a 30fps stream to my TV. I can watch a smooth looking football game, and they can also provide buttery smooth slow motion replays. That's what I'd like to be able to do?

Why don't you try what was suggested and see if you get the results you need?  There is no better advice or approach that I am aware of.

Don't expect your footage to look like an NFL game.

TrevorSK Posted at 2019-6-24 10:46
Maybe I can ask this question: How do the sports networks shoot? I know my cable company provides a 30fps stream to my TV. I can watch a smooth looking football game, and they can also provide buttery smooth slow motion replays. That's what I'd like to be able to do?

Hi there!
You don have to worry about you final video fps for calculate your shutter speed. For you case:
- Take the video at 120 fps. If your target fps for the video is 30 fps you will be able to slow down the speed for the slowmotion to a 25% without needing to generate frames with software.
- Set the shutter speed the closest you can to 1/240.
- Now set ISO to minimun and try the differents nd filters if you have. Select the one which give you an image without burned whites.

djiuser_xaoojN3Q24Fx Posted at 7-18 10:32
Hi there!
You don have to worry about you final video fps for calculate your shutter speed. For you case:
- Take the video at 120 fps. If your target fps for the video is 30 fps you will be able to slow down the speed for the slowmotion to a 25% without needing to generate frames with software.

Thanks for the answer. That's exactly what I've been doing lately but it's good to have clarification. I tend to second guess if I'm doing things in the best possible way. I'm just an amateur.

Shooting at 120fps will slow down 4 times your playback speed on a 30fps timeline. That’s fine HOWEVER, this means that all your footage will be played back in slow motion! You can’t mix different timelines. The only solution is that you film some clips at 30fps & 1/60sec and some others in 120fps & 1/60sec, then you can combine  them just fine on a 30fps timeline

Using a shutter speed double of your FPS will create a more natural and pleasant look, that’s the correct thing to do.