EX3's have any problems with 5600k Flourescent Lighting?

[Glynn Morgan]

I read somewhere that the CMOS chip may have problems with fluorescent lighting. Is this a myth or true? I read that the frequency of certain lights can cause banding.

I'm looking at getting some 5600k florescent softboxs for interview situations, is this unwise with the EX3?

Cheers

[Bruce Watson]

Originally Posted by Glynn Morgan

I read somewhere that the CMOS chip may have problems with fluorescent lighting. Is this a myth or true? I read that the frequency of certain lights can cause banding.

I'm looking at getting some 5600k florescent softboxes for interview situations, is this unwise with the EX3?

The only problem I'm aware of is frequency. If your fluorescents are running old style magnetic ballasts, they probably run at power line frequency. That would be 60 Hz in North America, or 50Hz in Europe. If this is the case, in order to avoid an odd sort of banding you'll want to use a frame rate that's an even multiple of the power line frequency. So, 30 or 60 frames per second (fps) in North America, or 25 or 50 fps in Europe. What this does is ensure that each frame in your video is exposed during the same part of the power line sine curve. If all frames get the exact same exposure, no banding problem.

Note that modern electronic ballasts on fluorescent fixtures designed for film / video use will have frequencies far higher than power line (some are in the 40,000 Hz range). This makes them essentially constant light sources for you, so you don't have to worry about matching your frame rate to the power line.

[Robin Probyn]

what a great explanation ..

[Glynn Morgan]

Originally Posted by Bruce Watson

The only problem I'm aware of is frequency. If your fluorescents are running old style magnetic ballasts, they probably run at power line frequency. That would be 60 Hz in North America, or 50Hz in Europe. If this is the case, in order to avoid an odd sort of banding you'll want to use a frame rate that's an even multiple of the power line frequency. So, 30 or 60 frames per second (fps) in North America, or 25 or 50 fps in Europe. What this does is ensure that each frame in your video is exposed during the same part of the power line sine curve. If all frames get the exact same exposure, no banding problem.

Note that modern electronic ballasts on fluorescent fixtures designed for film / video use will have frequencies far higher than power line (some are in the 40,000 Hz range). This makes them essentially constant light sources for you, so you don't have to worry about matching your frame rate to the power line.

Cheers! I also read that you can use the same setting as you would for shooting TV/Computer screens to eliminate the banding. I assume, given your explanation, that this would also work if banding occurs.

[Alister Chapman]

If the frequency of the fluorescent lights is close to that of the camera as well as the more commonly visible rolling light/dark band you can get a slow colour phase shift over several seconds that continuously subtly changes the hue of your images.

It's not uncommon to see this in an office environment where different parts of the office can take on different hues where light fixtures in different areas may be running off different phases.

Most professional fluorescent video lights use high frequency ballasts so should be OK. Just make sure you have good tubes that don't have too many hours on them as as the tubes age the gaps in the light spectrum get worse.

[Richard Cavell]

Just for the record, I shoot under office fluorescent lighting with an EX1. I shoot with automatic white balance. I don't really have a choice about lighting conditions - it's an office and we have safety problems with using "proper" video lighting, as discussed in another thread. The mains power is 50Hz and I'm shooting in 1080/50i.

The optics and CCD part of the EX1 are identical to the EX3.

I confirm that the camera does undergo a kind of white balance shift, where the cream-coloured walls change colour, pulsing slowly every few seconds. It's weird. Not much I can do about it. What we're doing doesn't really mandate colour grading. I simply try to take people outside in the sun as often as possible.

Richard

[Bruce Watson]

Originally Posted by Glynn Morgan

Cheers! I also read that you can use the same setting as you would for shooting TV/Computer screens to eliminate the banding. I assume, given your explanation, that this would also work if banding occurs.

Well, it sorta depends on the computer screen. I've got an old NEC CRT that runs at 85Hz so it doesn't flicker for my eyes. I'm not sure how I'd shoot that. Probably I would pull the CRT refresh rate back to 60 Hz and shoot it at a 1080p30 like I would shoot under crappy old fluorescents.

For computer screens, I'd be sure to schedule some time for test shots just to be sure.

[Jacques Mersereau]

Our 'house' fluorescents (regular home depot type - cheap) have a noticeable rolling band that Alister talks about, while our Kino Flo 4 banks we use for our green screen set up are clean. I don't think that color temp matters, but have yet to use the 5600º tubes in our kino's. I would be surprised if they made any difference when it comes to strobing or rolling dark bands.

[Robin Probyn]

If you kino,s strobe there is something very wrong with them thats for sure..

Just as aside.. many people,like myself ,actually purposely mix tungsten and daylight tubes in the 400 diva.

I usually set the camera for tungsten.. but with all 4 tubules tungsten its a bit on the orange side..

Most office/shop flories are around 4,300.. I believe this is why many camera,s have that as one of the standard settings..

[Derek Reich]

I have had frequent issues with flouros when traveling abroad. (I am referring to house/office lighting, not Kinos here) The EX has problems dealing with flouros operating on a different cycle than the camera is set (ie: 50 cycle flouros when the camera is set to NTSC 30p or 60i) The flicker reduce feature helps sometimes, but not always. On a recent trip to Helsinki, this problem was exceptionally bad at various schools I was shooting in, but curiously I could be in one room and be fine, and an adjacent room visible through a doorway was flickering badly. Perhaps that was because the flicker reduce was working in the room I was in, but the adjacent room was slightly out of sync or something? In any case, it was pretty irritating, but nothing could really be done for it. (lighting the rooms was not an option) Also interesting was the fact that if the camera was stationary, the flicker reduce worked best.... when the camera made a move, (either hand-held or panning on a tripod) the flicker became noticeable momentarily, until the camera was stationary again.
I've never had a problem in a 60 cycle country, or with any Kinos or Kino knock-offs.

[Dave Sperling]

Instead of using the 'Flicker Reduce' feature, try to adjust your shutter speed to eliminate the flickering.
Where it gets tricky is when there are several different frequencies involved, such as overhead fluorescents and crt monitors of varying frequencies all at the same time.

[Alister Chapman]

This isn't an EX specific problem. Any camera can suffer from strobing under fluorescent lights. It tends to be most noticeable on CMOS cameras due the rolling shutter.

[Daniel Epstein]

Originally Posted by Dave Sperling

Instead of using the 'Flicker Reduce' feature, try to adjust your shutter speed to eliminate the flickering.
Where it gets tricky is when there are several different frequencies involved, such as overhead fluorescents and crt monitors of varying frequencies all at the same time.

Dave has the best idea here. Irregardless of your frame rate you want the shutter rate to match or be a multiple of the frequency of electricity of the country you are in. (CRT Computer displays excepted) For example Even if I am shooting 60i, 30P or 24P in a country with 50 hz electricity I want to shoot at 1/50 or 1/100 shutter (if the camera isn't capable of 50) if I am worried about flicker from light sources. When I shoot 24P here in the states I often use 1/60 as a shutter rate if I don't know what light sources I am going to be dealing with. As for how well some cameras deal with the phasing issues other than the basic frequency I can't say anything about specific sensors without testing.

[Derek Reich]

I tried all different shutter speeds, frame rates, and the flicker reduce. On that particular trip to Finland, the only thing which had any effect at all was the flicker reduce. Changing the shutter didn't help at all.

[Robin Probyn]

Thats very odd.. the lights must have not been running from the mains ? very old ? you might get one to two bulbs that about to go.. but all the rooms.. thats weird.. If you have a lot of day light coming in.. it can over power the flicker effect to some degree.. maybe the other room you could see had the curtains drawn or was not getting as much day light.. even so for a school presumably running off mains power the shutter should be able to get rid of that flicker.. Sodium lights can be a lot harder..