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Shooting 25fps in a 60hz country


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#1 Jamie Kennerley

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Posted 26 May 2014 - 11:27 PM

Hi there,

 

I'm about to start shooting a short drama in Brazil - 25fps as it's a UK production. Shooting on the F55.

 

It's largely exteriors and very little lighting, but we do have a big interior scene in a location full of bog-standard fluorescents.

 

Am I going to need to change my shutter angle to 150 degrees to deal with potential flicker for that part of the shoot, since Brazil is 60hz rather than the 25fps-friendly 50hz? Or am I likely have to do much more fine-tuning of the angle...?

And will I definitely be able to solve whatever flicker I encounter?! I would hate to get to that part of the shoot and be regretting our decision to stick with 25fps!

 

Thanks so much in advance,

 

Jamie


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#2 Brian Drysdale

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Posted 27 May 2014 - 01:49 AM

150 degrees is the safe shutter angle in a 60hz country using 25 fps. When shooting with my Aaton I used to shoot at 24fps with a 180 degree shutter on otherwise 25fps productions because of florescent flicker in 60 Hz country.

 

Although I guess you may have to fine tune if there was a local variation in the  mains frequency. There is a continuous shutter setting mode in the F55, which should allow you to clear any flicker by eye.That's a similar process to what was done with the adjustment control to clear flicker on CRT computer screens on ENG cameras.


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#3 Phil Rhodes

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Posted 27 May 2014 - 05:32 AM

My experience is that with modern ballasts it tends to be quite a subtle problem anyway - not so subtle that you wouldn't want to do something about it, mind, but that's when it gets complicated. Electronic ballasts usually work at high frequency, which may create problems of its own. The bigger issue is that the high frequency may be modulated with the mains frequency, particularly with cheap or malfunctioning ballasts, creating a problem that's hard to solve.

 

P


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#4 Jamie Kennerley

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Posted 27 May 2014 - 06:50 AM

Thanks Brian, Phil. This is my quandry really - whether to just shoot 24fps to have a safer starting point, like all the locals do. For the one big-lit scene I'll be using HMIs plugged from the wall, mixed with the local flourescents in the space. In some ways I'm not so worried about that bigger scene because we have plenty of visibility and time to setup. It's more should we pass by bars and shops etc (we're doing lots of car shooting) and we catch a glimpse of the interiors and they're flickering, and we didn't notice or couldn't adjust at the time.

 

Maybe it's just a safer starting point to shoot 24fps with a 180 degree shutter? Would you agree?


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#5 Brian Drysdale

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Posted 27 May 2014 - 07:06 AM

24 fps would be the safest and Brazil may not have the most modern electrics in some places . However, I would check with your post people in case doing so raises any issues for them. I recall an Avid licensing issue on one production.


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#6 Jamie Kennerley

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Posted 27 May 2014 - 07:30 AM

How d'you mean by an Avid licensing issue? Sure the ability to edit 24p is available across all post suites now isn't it?!


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#7 Brian Drysdale

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Posted 27 May 2014 - 08:46 AM

That's an issue from the past, but it's just an example of something to be confirmed in advance, rather than assumed, in case something comes left field at you. If everything is set for a broadcast world in your post house, 24fps may throw an unexpected hiccup into the chain. Never mind the 23.976 fps that they use in the US.

 

Another would be the checking the time code.


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#8 Jamie Kennerley

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Posted 27 May 2014 - 01:11 PM

I guess 23.98 is the safest format to shoot here for broadcast, yes? But since this is a short for the festival world before anything, I think 24p is our best bet to not encounter flicker whilst shooting here.
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#9 Phil Rhodes

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Posted 27 May 2014 - 01:20 PM

In theory, 24p should be safe under 60Hz light at any shutter angle, but unfortunately the bad-electronic-ballast issue can fox that regardless.


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#10 Brian Drysdale

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Posted 27 May 2014 - 03:01 PM

I guess 23.98 is the safest format to shoot here for broadcast, yes? But since this is a short for the festival world before anything, I think 24p is our best bet to not encounter flicker whilst shooting here.

 

23.98fps is NTSC land stuff, assuming you're doing post, in the UK check with your post people first, they may prefer 24fps, especially if working with time code.


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#11 Jamie Kennerley

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Posted 27 May 2014 - 08:47 PM

Thanks to everyone here. We're going with 24fps!


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#12 John Miguel King

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Posted 31 May 2014 - 11:36 PM

Get this. Free and never failed me.


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