Flicker from Kino powered by genny

Jim Hyslop · March 13, 2009

Hi,

I was 2nd AC on a short film a while back, and we shot a scene on location. One of the lights we used was a KinoFlo. Power was provided by a diesel trailer genny. When I watched the film, I noticed the Kino was flickering. Could that have been caused by the genny not generating exactly 60 Hz, or by the camera being slightly off-sync? Or would you have to see the shot to be able to comment?

--

Jim

Ryan Thomas · March 13, 2009

Unless you were shooting some strange shutter, I'm just going to take a stab at it and say that the genny's voltage was a little off. That could be culprit with the flicker. You would just have to adjust the voltage on the genny while you measure it with a voltage meter to make it correct.

Edited March 13, 2009 by Ryan Thomas

JD Hartman · March 13, 2009

Only the Kino seemed to be flickering? Could be a bad tube. If the generator voltage was low, light from any Tungsten fixtures would have looked a warm on the monitor. Flicker is caused by power frequency not voltage.

Jim Hyslop · March 14, 2009

I forgot to mention we were shooting on an Arri SR3, which has a fixed shutter.

Yes, only the Kino was flickering - the tungsten lamps were fine.

A couple of other factoids that may affect things: it was just above freezing, and we ran into problems with the battery later that day. Could the cold or a low battery voltage have affected the camera speed?

Edited March 14, 2009 by Jim Hyslop

JD Hartman · March 15, 2009

In general florescent lights don't like the cold. Did it seem like the tubes took a while to reach full brightness. I can't comment on Kino's electronic ballasts, but most floro ballasts will have problems with low temperatures. Reliable operation at low temperature requires a different design.

Adrian Sierkowski · March 15, 2009

Arri SR3 has a variable shutter... If you hold down the "Phase" button on the camera you can be certain of where it was set.

I would say perhaps cold on the floros and/or an older/bad tube.

Jim Hyslop · March 17, 2009

Arri SR3 has a variable shutter... If you hold down the "Phase" button on the camera you can be certain of where it was set.

Oh. Good thing I was only 2nd AC :-) Thanks for the info. I've downloaded the manual but haven't had a chance to read through it yet.

So, the consensus seems to be either a bad tube or the cold. Is there any kind of test we could have run before shooting?

BTW, the flicker was fairly subtle - most audience members probably wouldn't notice it.

Thanks for all the replies!

Jamie Metzger · March 17, 2009

[quote name='Jim Hyslop' post='278182' date='Mar 16 2009, 08:24 PM']Oh. Good thing I was only 2nd AC :-) Thanks for the info. I've downloaded the manual but haven't had a chance to read through it yet.

So, the consensus seems to be either a bad tube or the cold. Is there any kind of test we could have run before shooting?

BTW, the flicker was fairly subtle - most audience members probably wouldn't notice it.

Thanks for all the replies![/quote]

SR2 has a fixed shutter. There could be the possibility that the shutter was at a different degree, and it wasn't a safe angle. I know on the sr3 you can shoot 24/25/29.97, and if you were at 29.97, a kino would definitely flicker, as would HMI's.

Too many variables though. Ballast, and the tube seem more reasonable.