Fluorescent Lights

[Jackson Miller]

Are there any problems using the EX1/3 or other CMOS cameras in fluorescent lighting? Is this a CMOS thing? Do you guys have any idea what I am talking about? I thought I read something about strobing or something. How serious is this?

The reason why I was wondering is because I was going to buy some fluorescent video lights from cool lights? Would these cause problems? It wouldn't be very smart to have lighting equipment that caused problems to your footage.

[andykwilkinson]

You will risk getting strobing if you don't set your shutter to 1/60 in countries with 60Hz power supplies or 1/50 in countries (like here in the UK) that use 50Hz. You also should be able to use multiples of the key frequency as a shutter speed without issue (e.g. 1/120 in 60Hz countries and 1/100 in 50Hz countries, assuming this gives you want/need) but, as always, do a quick check at your chosen settings and look at it on a big monitor to confirm all is OK before shooting anything important. Hope this helps!

[MitchLewis]

I asked the KinoFlo guy this specific question at NAB last week. He smiled and said that their lights operate at something like 10,000hz (I can't remember the exact number). So there's no way they will cause a strobing issue unless your running a shutter speed set in that same range (I don't think any camera's have shutters that operate in that range). He did say that some of the less expensive fluorescent light manufactures do sell lights that operate at a much lower frequency and that could cause problems, but he wouldn't mention any specific names.

I guess it's just buyer beware. :)

The two fluorescent light set ups I'm looking at are the KinoFlo Diva lights and the Lowell Case Lights. I shoot with an adaptor so I need a fair amount of light. If you're not using an adaptor then you could get away with using a smaller light kit.

[Barry_Green]

It's not strobing, it's rolling waves that move through the image. If you are shooting under magnetic-ballast fluos, you have to match your shutter speed to the frequency of the electricity (meaning, 1/60 for NTSC countries, or 1/50 for PAL countries). You are actually pretty safe if you use multiples, you you could do 1/40 or 1/30 in NTSC, 1/25 in PAL, and still be okay.

Same restrictions apply for magnetic HMIs and sodium vapor or mercury vapor lights too.

If you're dealing with high-frequency electronic ballasts (such as kino flos or electronic HMIs) then this isn't really a worry at all; you might only get iffy results if you're using extremely short shutter speeds (maybe 1/2000 might cause an issue.)

And yes, this is a CMOS issue, it affects the Red, the EX1/EX3, the HV20, the HPX300, any CMOS camcorder that uses a rolling shutter.

[MitchLewis]

If that's true, then why have I had no issues shooting under fluorescent lights with the shutter turned off?

I'm not trying to start an argument, I'm just trying to better understand the limitations of our camera. :)

[Jackson Miller]

Hmmm. Does anyone know if cool lights have these problems?


Also, I could have sworn with my DVX that I got some strobing sometimes that had to do with setting the shutter speed. Aren't you supposed to set it at twice the shutter speed or something? For a CCD cam? Jeez, I don't know what I am talking about.

[Barry_Green]

If that's true, then why have I had no issues shooting under fluorescent lights with the shutter turned off?
What's the "shutter off" speed, 1/24? If so, that's a multiple of 120 (it's 5/120) and therefore an appropriate speed. You're looking for multiples of the line frequency, so 1/120 should work, 2/120 (i.e., 1/60), 3/120 (i.e. 1/40), 4/120 (i.e., 1/30) and 5/120 (i.e., 1/24) should all work.

1/40 or 1/60 are the closest to 1/48 and would be the speeds I'd recommend to a CMOS user in NTSC/60Hz territories.

[FrankC]

Barry, I so appreciate your advice! This explains why I got the "rolling" with my HV30 (CMOS probably set at 1/60) while shooting under flourescents in China ( a 50Hz country).

[dpryke]

It is a problem with CCD's too. I had a shoot in the US, using a Sony Beta 600 PAL camera. I had to set the shutter speed to 1/60 so that I could shoot in the office under fluorescence and avoid strobing. It's the electrical current you are trying to match. 60Hz US and 50Hz Europe. Hence setting the shutter on a PAL camera running at 50Hz to 1/60 shutter speed for fluorescence running at 60Hz.