Is it possible to shoot and edit in 28fps?

L

Lkorver

Well-known member
Shooting an industrial on LED accent lighting. The only way I can get them to not flicker on camera is to shoot 28fps in 30PN mode on the hpx170 (tried syncro scan and shutter adjustments to no avail).

What are some possible issues with editing in or with 28fps footage?

thanks!
Luke
 
It seems odd that frame rate fixes what shutter speed won't -- but you're the one doing the tests.

If there is no sync audio (and I'm guessing there isn't, if you are shooting 28Fps) just conform to 30Fps if you can live with a 6% overall speed increase, or 24Fps if you prefer a 12% overall speed decrease. Having shot many industrial floors where I settled on a speed decrease as being more pleasing (though more typically a 33% or 50% final speed), I'd encourage you to look at the decrease first over the increase. Either way, you aren't dealing with problematic values. If there is sync audio, the problem becomes more difficult & you'll have to make some audio compromises ... but you can still do it with pitch shift and just plain mis-synced audio.

Cheers,
GB
 
Hmm- I hope that's not every shot. If it's just a couple I don't see a big issue though.
 
We will have a presenter speaking (audio recording into camera) on camera with the leds on in the background for some of it, the rest is b-roll. For the b-roll, the frame rate issue shouldn't be a problem as I will just conform if necessary. But for the talking head footage I could be screwed right?

can i record audio/video on the hpx at 28fps and edit and export with everything looking/sounding normal? or am I forced to conform to either 24 or 30p??

I'll have to run a test to see what I can do in post but if anyone wants to chime in with pre-existing knowledge that time that would be sweet...
 
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RGBaker said:
It seems odd that frame rate fixes what shutter speed won't -- but you're the one doing the tests.
If there is sync audio, the problem becomes more difficult & you'll have to make some audio compromises ... but you can still do it with pitch shift and just plain mis-synced audio.

GB
Click to expand...

So you're saying if I reconform the audio to match 24p video, i'll just need to sync audio and ajust the pitch until the voice sounds normal? or does adjusting pitch adust the audio speed?
 
Hmm- no with audio that's going to be kind of a cluster-f in post. I'd work with a gaffer and/or an engineer to figure out how to sync up with the lights properly at a regular frame rate. Otherwise you may be really shooting yourself in the footage with sync in post. 28fps is definitely not a regular sound sync speed frame rate.

Noah
 
Are you shooting pN mode with the 180-degree shutter? if so, it may not be the frame rate that's fixing the flicker, but the actual shutter speed. Go into video cam mode, and set it on 24p or 30p, and set the shutter on syncro scan, and then cycle through the syncro scan shutter speeds, you should be able to find one that fixes the problem. Based on 28fps, I'd say it's about 1/56.0.
 
Barry_Green said:
Are you shooting pN mode with the 180-degree shutter? if so, it may not be the frame rate that's fixing the flicker, but the actual shutter speed. Go into video cam mode, and set it on 24p or 30p, and set the shutter on syncro scan, and then cycle through the syncro scan shutter speeds, you should be able to find one that fixes the problem. Based on 28fps, I'd say it's about 1/56.0.
Click to expand...

Yes, shooting in PN mode with 180 shutter.
I didn't think of setting to video mode...will have to give that a try. I did cycle through the shutter angles while in film mode and didn't find any value that fixed the issue. Could the video mode/ syncro scan still work?

thanks Barry
 
I heard back from the tech guys who built the LED's in question. The lights beat at 28 and 1/8th beats per second. How would I go about calculating the proper syncro scan for that rate? thanks!

Luke
 
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Well, you could try 1/28.8 in the syncro scan, or half of that (1/57.6) and that'll probably get you pretty close, then tweak up or down from there.
 
Just a thought but can you ask the engineers if it's possible to reset the pulse rate to 24fps? Otherwise they'll have this same issue every time they go to film their lights. Marketing point...

Noah
 
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