Need tips for shooting auto racing video

[neosec]

I made an attempt to shoot video at a small oval race track last week, it was my first time shooting video with the 5D Mk III (or much of anything else for that matter). I'm disappointed with the results. Because of the speed of the cars I thought shooting at 60 fps would be a wise choice for better slow motion of the inevitable accidents. This meant 720p. The video is very soft, I've read since that some consider 720 to be unusable.
My setup was: 24-70 @ 70mm w/ f4-f8 (changed as the sun went down), 720 @ 60 IPB (>4 hours of shooting so space issues, don't want to change cards in the middle of a race), ISO 500 - 12800 (again, changed as the sun went down, poorly lit track) Tripod was used (paned with the cars), Zoom H4n (audio is fine).
Would 1080p 30 be a better choice with the trade off of slow motion? And perhaps a shutter of 125 or higher for a sharper look?
Most of the action happens at > 150 ft from the camera, the closest I get to the cars is ~50 feet.
TIA

 

[kaihp]

I've shot onboard videos (motorcycle) with both 720p@60fps and 1080p@30fps, using a ContourHD camera.
My experience was that 60fps gave a better video quality (even when played at 30/25fps).
Since the camera is fully self-contained, I cannot advice on the shutter, beyond guessing that a faster shutter will most likely help.

 

[neosec]

Thanks for the reply kaihp,
I had the same expectation with 60 fps. I had a GoPro Hero mounted at one of the corners of the track shooting @ 1080/60, the very wide angle (fish eye) lens took in the whole track. Those wearable action cams do pretty good very close up, not so much for a larger scene. I think I'll mount the Hero in a car or right on a guard rail where the cars pass close.
Since I'm just starting with video and have much to learn, I thought I'd ask here in hopes of not having to learn everything the hard way. There's only one take in auto racing.

 

[ckwaller]

You mentioned shooting @ 720p/60fps. What shutter speed were you using? I've always read that when shooting 720p, a shutter speed of 1/125 (essentially twice the frame rate or its nearest approximation on a DSLR) is ideal for creating slow motion shots in post.

Otherwise, you can shoot at 24/30 fps and use programs such as Twixtor/After Effects or Cinema Tools to achieve the desired effect?

 

[cookinghusband]

You mentioned shooting @ 720p/60fps. What shutter speed were you using? I've always read that when shooting 720p, a shutter speed of 1/125 (essentially twice the frame rate or its nearest approximation on a DSLR) is ideal for creating slow motion shots in post.

Otherwise, you can shoot at 24/30 fps and use programs such as Twixtor/After Effects or Cinema Tools to achieve the desired effect?

I have tried using 1/125 when shooting 24p, the results are still OK, see if this is ok with yourself. will feel choppy if you go higher .