GH2 crap venue lighting

tired

tired

Well-known member
This isn't really a lumix problem but since I shoot with GH2's I thought it was a place to start.

I have a venue that recomends me and I'm at the point of asking them not to - they use a new type of LED lighting and it's a pain - everything has a yellow cast (that's not too hard to fix in post but the flickering is a nightmare - unless the lights are on full (which is still pretty dim) there's a flicker which I can't eliminate. a shutter speed of 125 seems to minimise it but it's still significant. I'm told it's due to 'pulse width modulation' but with venues insisting on 'romantic lighting' and constantly wanting to dim the lights it a major drama.

with other venues I can bring along my own lighting to suppliment but with this place I'm buggered - I don't see changing cameras helping and if I start insisting that they leave the lighting on full, they'll stop recommending me anyway. So.. before I bite the bullet and tell them thanks but no thanks does anyone have any ideas?

https://vimeo.com/62484278
 
Try shooting at 1/60th or even 1/50th - and I'm sure you can get rid of the yellow cast with a proper white balance. If a WB doesn't work, go to the K colour temperature setting and set the colour manually by moving the temperature control.
 
the WB isn't the problem - I mentioned it in case someone had come across similar lighting. Shutter speed isn't the solution either, I've tried everything from 25 to 250 and 125 gives the best result and the flicker is still there. As I understand it the problem is caused by the LEDs being switched on and off at a high frequency so they can be dimmed.

http://www.led-lamps.net.au/led-dimming-a-effects/led-dimming
 
I use LEDs as part of my normal lighting, dimmable ones and haven't seen this particular problem.

I've shot with them at 25, 50 and 100 shutter speed (I'm UK so PAL).
 
Faster shutter speeds and PWM are not happy partners, but that's how it is. The problem with video is much better with products from people like Arri, but the real issue is the fact that there is no filament warm up time, which evens out the pulsing from AC mains. There are other performance issues too, a snap blackout in theatre (a common feature) was never a snap with tungsten, just a quick fade out. With LED, snap=snap. LEDs by their nature produce their light output instantaneously and not a gradual light up or light off as in a 'lightbulb'. Most cheaper designs will have no output for half the mains cycle, when set to 50%, so for the camera - for half the time there is no output at all, but when there is, it is full - so the strobing appears instead of dimness. LED fixtures do really good strobe effects, just as tungsten can't - so flicker in the cheap ones can even be seen by your eyes, especially your peripheral vision which is more sensitive to flicker. I've returned some LED products because as they start to dim, the flicker is unbearable. Better designs use more sophisticated dimming circuits that usually run at a higher frequency, or use frequency independent circuits to give smooth dimming. To the video person, the cheap LEDs flicker badly, to the LD, they just dim badly - usually running out of available steps at the bottom end. With tungsten, you can cheat in an almost invisible glow at around 5-10%, with a LED it doesn't work, you get no light, then a big jump some light. No control at all!

The only real disguise is to shoot at the lowest frame rate you can - 25 seems to look better to me than 50, or mathematical multiples - but keep in mind that when they dim the lights, the entire thing can become unstable. If you give the lighting op a monitor, they can often minimise the problem, but rarely remove it. My 3CCD proper camcorders seem much better at this than stills cameras that do video. We did a show yesterday and the EX-3s were making a decent job of the stage lit with a mix of LED and tungsten, but the video guy who shoots for this ciient never uses his DSLT kit in our venue because of the flicker issue. The EX-3 seems to have few problems.
 
Great comprehensive answer there Paul.

Perhaps it could be pointed out to the venue owners that even if they recommend someone else, the problem will not go away? They may not like being told their lighting is crap, but at least you care enough about the product to raise the issue. Can you maybe get access to the room during some down time, and experiment dimming at different levels?
 
The peripheral vision trick is the only way likely to convince sceptics there actually is a problem, but some people simply won't be able to see it.
 
Just as Paul said, there's not much you can do about it with DSLRs. I just shot a concert under the same types of LED lighting and flicker is a huge issue with no real solution. Changing shutter speed won't do it. I try to rent small-chip CCD cameras when shooting under LED stage lighting, as the flicker is not nearly as pronounced on those. Many lighting guys are familiar with this problem (as well as the terrible CRI when using LEDs set to any color other than white), but there's often not much they can do about it.

P13 said:
I use LEDs as part of my normal lighting, dimmable ones and haven't seen this particular problem.

I've shot with them at 25, 50 and 100 shutter speed (I'm UK so PAL).
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Stage LED lighting is NOT the same as LED lights designed for film/video work. I use 1x1s all the time with no issues, but the cheap stage LED par cans are a nightmare for video.
 
stefancolson said:
Stage LED lighting is NOT the same as LED lights designed for film/video work. I use 1x1s all the time with no issues, but the cheap stage LED par cans are a nightmare for video.
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I see, I've not had the displeasure to encounter a stage LED par can yet.
 
So it sounds like tired should try as suggested and rent a CCD camera, because if tired leaves the job and next camera person comes along with a CCD camera and has no issue then it'll look like tired's camera work was at fault.
 
but some people simply won't be able to see it.
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i had this happen with a gh2 and some under cabinet lighting on a shoot with a custom home builder.
fortunately either the client didnt notice it - or didnt care...

I try to rent small-chip CCD cameras when shooting under LED stage lighting
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i will let go of my hpx170 when they pry it from my cold dead hands : )
in fact, if i did more live, event shooting. i'd pick up a couple more from these nitwits selling theirs off for DSLRs as im seeing more and more venues outfitted with cheap chinese pars
 
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i will let go of my hpx170 when they pry it from my cold dead hands : )
in fact, if i did more live, event shooting. i'd pick up a couple more from these nitwits selling theirs off for DSLRs as im seeing more and more venues outfitted with cheap chinese pars
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I agree , for those that do a variety of shoots, a 1/3rd or 1/4" ccd chip is a must have in the toolbox. when used to full potential, and a little post sharpening, these older camcorders can look damn near as sharp as the newer cmos models, ccd's are priceless in certain scenarios. Heck for under 2k, I can't see any good reason not to have one in the kit.
 
i dont really consider that a solution. AND id have to operate in that godawful hellhole that boris calls a user interface...
 
Makes it bearable I suppose. Do you work for Boris? Virtualdub also has a temporal smoother plugin included that does a similar job. I used it once: I had a shot which in the background had a CRT monitor, got the old 'rollover'. It wasn't a main part of the shot, but it was distracting having it in the background. A quick mask and application of the temporal smoother to just that part, et voila! :)
 
Boris Continium only works sometimes. It's very hit and miss.

The best fix is Foundry's Furnacecore (Deflicker2). But it's expensive and the render times are beyond insane
 
Ironic, after hearing about this issue in this thread last week, this weekend I've shot some live video in a music venue using LED parcans and experienced this issue first hand. The venue themselves had Sony CCD cameras but that footage didn't look great either albeit it didn't suffer so bad with the flicker.

As it was a music video I've gone for a stylised look (i.e. I've crushed the issue out with some effects and gone to a monochrome look), the bits of flicker left I'm hoping to the untrained eye are just considered pretencious music video effects. :grin:
 
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What I would try, merely cause I do it as a hobby, is sync (or rather off-sync) the LED lights in that venue using a central power supply for the LED lights in that venue, and using a microcontroller, have the LED lights flicker (PWM) in such a way that with overall venue lighting, there won't be any (or very little) flicker. Basically, when one LED light goes LOW (the PWM wave is a square wave with a HIGH and a LOW) the other LED's will be on the HIGH, etc. Well, that is what I would've tried if I enjoyed shooting at the venue and still wanted to make it work for both parties.
 
Nope - won't work because there's no adjustment available to alter the trigger point of one fixture against another in time, only how long the on section is. Practically all cheaper units use the mains frequency to trigger the on/off sequence. There are better designs that use a different system that does away with the current limiting resistor by accurately triggering the on time as very short pulses so a 5 microsecond on followed by 45 microsecond off sequence. This tight timing suggests a better system of PWM control, which will be independent from the mains waveform. The benefit is even better efficiency - but could cause even more havoc with cameras with high shutter speed settings, making flicker even worse. These designs may also use an inductor to smooth out the on/off sequence - which should help flicker.

It's not really a new thing - the lighting people have been moaning about it for quite a while now - and it's still a pain!
http://www.blue-room.org.uk/index.php?showtopic=38673http://www.blue-room.org.uk/index.php?showtopic=38673
 
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