A7S: No 30fps, only 29.97fps?

2

2contagious

Member
Hi,

I have a PAL/NTSC switchable A7S and when in NTSC mode (to activate 30p), it seems the camera can only shoot 29.97fps, not 30fps: If I select 30p in the frame rate menu and check the file on my computer, it's 29.97fps. Also, recording externally via my Ultrastudio Mini Recorder, 30fps isn't possible, but 29.97fps is. Am I missing something or is 30fps not possible on the A7S?

I am asking as I have a Japanese client who wants me to shoot an interview at 30fps. Japan has the same 29.97fps standard for Television as the US, but I believe this interview will be for web use only.

I live in the UK, so I don't often shoot 29.97fps or 30fps, but I was wondering if there are going to be any audio sync issues if:

1) I record at 29.97fps on both my A7S and the Blackmagic Pocket Cinema Camera
2) Then sync the sound (in a 29.97fps timeline) from my Zoom H6 recorder in Premiere/Plural Eyes
3) Export 29.97fps video files with audio from Zoom H6 recorder synced
4) Import the files into Resolve as 29.97fps
5) And finally export at the end as 30fps from Resolve?

Do you think this might work?

–Chris
 
I've shot everything in 23.976 and 29.976 (and 59.97) on canon cameras for years and never had a problem, exporting with the same frame rate as shot. Usually with zoom audio as well. I only do web stuff, so I can't see why it would be an issue - all the major web video hosts and players support, or even expect, ntsc frame rates. Not sure why you'd want to export at 30.
 
wallrc said:
I've shot everything in 23.976 and 29.976 (and 59.97) on canon cameras for years and never had a problem, exporting with the same frame rate as shot. Usually with zoom audio as well. I only do web stuff, so I can't see why it would be an issue - all the major web video hosts and players support, or even expect, ntsc frame rates. Not sure why you'd want to export at 30.
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The only reason is that the client asked for 30fps. I looked up why that might be and there were some forum posts about there being audio sync issues when uploading 29.97fps footage to YouTube because it automatically changes it to 30fps?
 
I guess I would clarify with the client if they even understand the difference and know why they want 30 as opposed to 29.97. I've never had sync issues with youtube or vimeo because of this issue.
 
Japan is NTSC same as America. 30P is 29.97 FPS in NTSC standards there is no such thing as true 30 FPS. Your client will want the footage at 29.97 and will have no issues going to web or broadcast using that frame rate. There should be no synching issues with audio since you wont be changing the speed of anything. 1 hour of video at 29.97 will be exaclty that 1 hour of video so no issues synching it to 1 hour of audio, if you force it to be 30 fps on the other hand there will be synching issues as 1 hour of video is now 59 minutes and 54 seconds.
 
dhessel said:
Japan is NTSC same as America. 30P is 29.97 FPS in NTSC standards there is no such thing as true 30 FPS. Your client will want the footage at 29.97 and will have no issues going to web or broadcast using that frame rate. There should be no synching issues with audio since you wont be changing the speed of anything. 1 hour of video at 29.97 will be exaclty that 1 hour of video so no issues synching it to 1 hour of audio, if you force it to be 30 fps on the other hand there will be synching issues as 1 hour of video is now 59 minutes and 54 seconds.
Click to expand...

There is: Blackmagic's cameras can do 29.97fps as well as true 30fps for very slight slow-motion when taking it down to true 24fps in post. I always thought true 30fps was also used for web stuff though?
 
2contagious said:
There is: Blackmagic's cameras can do 29.97fps as well as true 30fps for very slight slow-motion when taking it down to true 24fps in post. I always thought true 30fps was also used for web stuff though?
Click to expand...

Not really very few cameras shoot it, so the vast majority of video for the web is going to be from a 29.97 source. Thanks for the tip about the BM camera, I own one and had completely forgot about that.
 
2contagious said:
I have a PAL/NTSC switchable A7S and when in NTSC mode (to activate 30p), it seems the camera can only shoot 29.97fps, not 30fps: If I select 30p in the frame rate menu and check the file on my computer, it's 29.97fps. Also, recording externally via my Ultrastudio Mini Recorder, 30fps isn't possible, but 29.97fps is.
Click to expand...

Welcome to the moronic world of dropframe timecode. An analog kludge left over from the introduction of a color subcarrier over the top of the B&W subcarrier and the audio subcarrier. Dropframe is the cheap and easy kludge to address the isual artifacts caused by the beat frequency between the analog color and analog audio subcarrier frequencies. The NTSC could have, and should have, fixed it right there. But no, they kicked the can down the road instead. :angry:

I was sure they would kill off at least interlacing and dropframe when we went from analog to digital. But no, they went for political "compromises" in a stupid turf war with the computer industry. The TV industry "won" and saddled us with "digital dropframe" which has zero meaning in the digital signal. Kind of like requiring that all pants have a tail hole when none of us have tails anymore. Utter mindlessness...

Just be thankful PAL didn't go there.
 
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