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Best shutter speed for 720 60P for a UK shoot.

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Andy Taplin
Best shutter speed for 720 60P for a UK shoot.
on Sep 29, 2010 at 9:54:08 am

Hi All

I'm shooting some footage in a UK laboratory/factory environment lit mainly with very bright overhead fluorescent tubes at 50HZ. It's for a US based client so I'm thinking of shooting in 720 60P (59.94) as some of the machines move quite quickly and I don't need the 'film look' of 24 or 25P. I'm thinking the best shutter speed for 60P and 50HZ lights would be 100th - anybody have other ideas?

Many thanks


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Todd Terry
Re: Best shutter speed for 720 60P for a UK shoot.
on Sep 29, 2010 at 2:20:35 pm

Well, for that frame rate a 1/60th shutter would give you a more "natural" look (which would be considered a "normal" shutter for that frame rate), but I understand the need to do the math with 50Hz lights. In that case, probably 1/50th would be the best looking choice. A 1/100th shutter might get a little stroby and choppying looking, especially with fast-moving machinery. And of course, there is a one-stop difference in exposure, if that's an issue.

At any rate, it would bear checking but if you are using the flos as the main (or only) light source you might need to tweak things a little more. Here in the US, flos (and other similar light sources) don't really flicker at exactly 60 times a second. 60Hz is really more something like 60.1... and I'm guessing in the UK it might be the same way (I don't know that for a fact though). In that case, it would be of benefit for you to use a camera that has a ClearScan mode, so you can dial in the exact shutter speed you need (it might end up being something like 1/50.1 of a second).

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Andy Taplin
Re: Best shutter speed for 720 60P for a UK shoot.
on Sep 29, 2010 at 2:36:28 pm

Thanks Todd

With 60P isn't anything less than 1/60th the same as having the shutter effectively off? Which is why I though 100th (or close to it) would cancel out the flicker from the flos giving me close to a 180ยบ shutter angle and 'standard' motion blur for that frame rate.

Normally here in the UK I would shoot at 25P with a 50th shutter of 50P with a 100th shutter and would probably not experience any flicker issues.


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Todd Terry
Re: Best shutter speed for 720 60P for a UK shoot.
on Sep 29, 2010 at 3:14:11 pm

Hi Andy...

No (depending on the camera) you can shoot at much slower shutter speeds, if you choose. If you go below 1/30th though (at that frame rate) you will simply get repeated frames. Now, not all cameras work that way, but I know mine does (I primarily shoot with the Canon XLH1 body).

And just cranking the shutter speed up higher than the power Hz doesn't necessarily solve the problem. You might not see flicker exactly, but you might see phasing... that is, your exposure gradually changes, sort of a "rolling hills" up-and-down of the exposure every three, four, or eight seconds... just depends on how the shutter is in sync (or rather, not in sync) with the power. It might not even be noticeable in footage played at normal speed. A lot of times guys think they don't have the issue at all, but then when they play footage fast (like shuttling through footage) the "waaah waaah" phasing becomes clearly evident. At normal speed, it may not even bother you.

Since you are there in the UK, it should be easy enough to a preliminary test with any regular household flo light (not a so-called "flicker free" instrument, like a KinoFlo). Although, if this is a big industrial facility they may be operating on three-phase power, which might make a difference. The best test will be one on the real location under the actual lights.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Andy Taplin
Re: Best shutter speed for 720 60P for a UK shoot.
on Sep 29, 2010 at 3:29:06 pm

Yes, I forgot about the slow shutter setting which my camera (PMW 350) has but I tend to think of it as a bit of a gimmick - useful for effects but not really useable as a proper shutter speed. As you say I'll need to test the actual set up as anything else will just be guess work.

I've seen that phasing you mention, by the way, when shooting under flos, it also seems to phase the colour as well, really noticeable in a white lab.


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