Shooting under fluorescent lights at 50 cycles

Bob Hayes · April 8, 2005

I?m currently shooting a feature in Thailand. 35mm 24 FPS. How do I deal with Fluorescent lights and HMI's? Thailand is 50 cycles 220. Ever other time I have shot in this environment I was shooting 25fps for a transfer to PAL and it wasn?t a problem. The one day a c-camera showed up set at 24 FPS I had a flicker problem. I hear shooting at 177 degree shutter solves it but my c-camera is a BL 4 that has set shutter speeds of 190, 180, 173. Hmm. What about weird frame speeds?

Thanks

Edited April 8, 2005 by bob1dp

April 8, 2005

Someone correct me if I'm wrong because I don't have experience shooting in countries with different electrical cycles, but I believe the shutter angle that will correct the problem is 172.8, so the 173 degree shutter should do the trick. I suppose it's worth testing out, and I could have my countries reversed, but that ought to do it.

April 8, 2005

Hi,

I'm a DP working in Thailand. You should always set the shutter in 172.8 (or 173) degrees when doing 24fps. If you want to do high speed (33.33 or 50 fps) with practical lights, shoot at 180 degree shutter and you will be OK with flicker. Do not shoot at 100fps or you WILL definately get flicker.

Other weird speed (undercrank), most ACs should have their little C.E. flicker free charts with them. If you need one, I think I have a spare around that you can have.

What lighting and camera rental house(s) are you using? Any help you need, please let me know.

Regards,

Picha

Bob Hayes · April 9, 2005

Thanks for the info. I'm using Gearhead. One of my camera guys is Pia. Is that you Picha?

April 9, 2005

Hi, Picha here. Enjoying yourself? I'm surprised your gaffer there didn't tell you the frame rate for shooting practical fluros. I'm in town the next couple of weeks, please feel free to call if I can be of any more help.

Bob Hayes · April 11, 2005

I haven't started shooting. I on Holiday till after Thai new year.

Rob van Gelder · April 11, 2005

Hi Bob, as others already said: 50 hz: 24 @ 172.8 degrees or 25 @ 180 degrees.

Rob van Gelder

Bob Hayes · April 17, 2005

I am also thinking of shooting some odd shutter angles 45 degrees and 90 degress and also some slow mo and maybe under crank. How is this different from the US?

April 17, 2005

Hi Bob,

Enjoyed the wet season this past week? :-)

If you are shooting 24 fps with practical fluros (and these energy savers bulbs with bulit-in ballast) in shot, you _will_ get flicker if you go 45 and 90 degrees.

You can undercrank at 20, 10, 5, 4 and 1 fps, but at 180. Otherwise, you'll have to use the CE crystal speed control to shoot at some weird decimal frame rate.

High speed, you can go 48 fps if you have to stick to 172.8. But if you go with 180 degrees, you can go 33.33, 50 and MAYBE 100 fps. 100 fps is really dependant on the condition of your practical fluros.

Enjoy,

Picha

Bob Hayes · April 18, 2005

Songkran festival was a blast. You guys have been very helpful. I have another question. How about non crystal sync HMI's a weird shutter and frame rates. I'm going to try to get flicker free.

April 18, 2005

Hi Bob,

Glad you like Songkran. It's been getting more and more out of control the past couple of years.

I wouldn't try to go any narrower than 25 fps at 90 degrees with magnatic ballast. I've heard of flicker problem with 25 fps and 45 degree shutter. I personally had problems with 50 fps at 90 degrees (which should be safe, in theory). With Gearhead's stock of new lights, I think their ballast are all flicker-free?

Other than the frame rates I've listed, there are a whole bunch of "safe" undercrank speeds, but they all required 3 decimal points, ie: 7.692 fps at 180 degrees. Or say 22.22 fps@80 degrees and such.

Does one of your assistant have the CE flicker free chart? I think I've given them some last year.

Enjoy,

Picha