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Sony NXCAM NEX-FS700 CineAlta
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Old May 8th, 2013, 04:57 AM   #1
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Slow Motion Flicker with Ari Redhead 800w lamps?

I have a shoot this weekend and will have two 800w redheads. Is this likely to cause significant flicker at 240fps?

I have been trying to research this and the advice is use 2k or 5k lamps ideally but a couple of videos I have found seem to be show that 800w is ok:



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Old May 8th, 2013, 10:43 AM   #2
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Re: Slow Motion Flicker with Ari Redhead 800w lamps?

I'd also like to know outside of BCC plugin, is there any other flicker fixer for POST? Either latest Premiere Pro or FCP 7? Does AE have any helpful tricks?

Here's my issue - going to shoot soon at indoor place - 240fps, 480fps
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Old May 8th, 2013, 12:39 PM   #3
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Re: Slow Motion Flicker with Ari Redhead 800w lamps?

I think you will get some flickering.
Personally I would use some HMI or high quality LED fixtures.
I have tried halogens up to 1000 watts and they flicker.
Hedler make some HMI's which are good value and do not flicker.
I have used these in the past up to 480 fps.
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Old May 8th, 2013, 02:03 PM   #4
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Re: Slow Motion Flicker with Ari Redhead 800w lamps?

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Originally Posted by Tim Davison View Post
I have a shoot this weekend and will have two 800w redheads. Is this likely to cause significant flicker at 240fps?
Yes. Absolutely.
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Old May 8th, 2013, 04:11 PM   #5
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Re: Slow Motion Flicker with Ari Redhead 800w lamps?

If they are traditional "redheads" then they have a tungsten bulb, which will NOT cause any flicker. There is always the chance that you may get flicker with HMI, fluorescent, halogen or LED depending on the ballasts used. I personally will now only rent HMI sources with a 1000Hz "flicker-free" electronic ballast if any high speed shooting is expected. I've had good luck with professional grade LED sources which have a DC converter. Consumer LED sources that use AC and only light for half the cycle will definitely flicker.

At your location you will want to turn off the house lights which look like fluorescent. Your two 800w tungsten sources will not be enough to light that whole basketball court, but you could probably get away with just lighting the player and the basket and shooting at 3200 ISO.
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Old May 9th, 2013, 04:11 AM   #6
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Re: Slow Motion Flicker with Ari Redhead 800w lamps?

Unfortunately I have no option with the lighting so will just have to see what I can do. However, if they are traditional tungsten redheads then I might be ok. There will be no other sources of light as we have a blackout box in which to film but will be shooting ballet dancers and the slowmo is a key part of this
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Old May 9th, 2013, 04:12 AM   #7
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Re: Slow Motion Flicker with Ari Redhead 800w lamps?

Quote:
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Yes. Absolutely.
Even if they are tungsten?
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Old May 9th, 2013, 07:00 AM   #8
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Re: Slow Motion Flicker with Ari Redhead 800w lamps?

Tungsten lamps don't flicker in general, because the light output is to all intents and purposes heat driven, not a direct electricity to light conversion. The 50 or 60Hz mains frequency is too fast to allow the filament to cool between cycles. Discharge lamps, as in HMIs have no filament so the light output is a direct result of the discharge - so they flicker. A higher wattage tungsten lamp has thicker filament coils, and the cool/heat cycle means the temperature change with the mains cycle is even less - but no tungsten lamps can cool down quicker enough to flicker.

The fact that some tungsten lamps do appear to flicker is usually down to lamp defects, where the fillament can physically vibrate - and this is a mechanical feature that can be detected my some people in their peripheral vision - and some cameras. It's worse in linear lamps - so 500W garden type floods can exhibit this effect, while a shorter DXX 800W lamp is less likely to do it. However - with proper branded lamps, this mechanical vibration is pretty rare nowadays, while cheap imported lamps can in some circumstances 'sing' - actually make a noise as the hot filament vibrates!

HMI needs a special filter to stop the flicker - no such device exists for tungsten, because there is no flicker to remove.

As for LEDs - full on, they are no worse than HMI, but as most use PWM if you dim them, the flicker can be dire!

I have no idea where the idea that HMI and LED flicker less than tungsten. I have over 50 tungsten fixtures in stock of all types, and about 30 different LEDs and discharge - including HMI and CSI - and the only ones that occasionally cause issues with faster frame rate video at the LED/Discharge types - never tungsten!
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Old May 9th, 2013, 01:25 PM   #9
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Re: Slow Motion Flicker with Ari Redhead 800w lamps?

Quote:
Originally Posted by Tim Davison View Post
Even if they are tungsten?
At high frame rates, yes. Try it and see. The tungsten filament temperature rides the power sine curve. The faster your frame rate, the more of this you'll see.

Don't take my word for it -- try it.
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Old May 9th, 2013, 06:13 PM   #10
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Re: Slow Motion Flicker with Ari Redhead 800w lamps?

Shot several 240fps shots last week with FS700 lit by a combination of Arri 300's and Ianiro Redheads - I had no flicker issues with them.
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Old May 10th, 2013, 09:10 AM   #11
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Re: Slow Motion Flicker with Ari Redhead 800w lamps?

Quote:
Originally Posted by Dave Sperling View Post
Shot several 240fps shots last week with FS700 lit by a combination of Arri 300's and Ianiro Redheads - I had no flicker issues with them.
What bulbs are you using?

The important thing is to test so you'll know. Many people do get flicker, especially with lower wattage tungsten lights. But there's so many variations it's always best to test.
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Old May 10th, 2013, 09:21 AM   #12
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Re: Slow Motion Flicker with Ari Redhead 800w lamps?

Not sure. We are receiving the lights tonight and will have a bit of time to test them before tomorrow's shoot. Fingers crossed!
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Old May 10th, 2013, 07:49 PM   #13
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Re: Slow Motion Flicker with Ari Redhead 800w lamps?

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Originally Posted by Bruce Watson View Post
What bulbs are you using?
Arri 300 would be FKW, though don't remember which brand (possibly ushio?)

Redheads either DXW (1000w) or FAD (650w) - normally use GE bulbs.

We were in a test lab setting, and tried doing one shot with one of their strobe lights. VERY interesting results. Some very strange flickers - though managed to more or less get rid of the 'scan line' artifacts by adjusting the strobe speed.. The director and agency seemed to like it - I was not that crazy about it. Certainly a different look though...
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