Varicam LT IR pollution - Clean Blacks.

A

Alex Derrick

Active member
Hey guys,
I messaged a few varicam owners regarding IR pollution, and I am getting mixed feedback. Some are saying no IR pollution, and one DP said he saw some redness in his blacks.

I shot some footage this evening and again noticed some types of black fabrics going red. I am thinking that the ND filters are IR corrected but the clear is not. Is anyone else having this experience?

Check out the old guys sweater w/ internal ND active vs ND clear.
very contaminated.

ir.jpg


I was under the impression that the varicam lt had some kind of removable IR filter to catch this kind of thing.

But now I am thinking I need to pull out the old 680 cut filter and do some more testing. REEEEAAALLY lame.

:(
 
The VariCam LT has a removable IR filter. Yours may or may not be currently installed.

An IR cut filter is not a one-size-fit-all sort of thing. IR is head, and the more IR that is present the greater the filtration that is needed. The internal NDs each have additional IR cut filtration of increasing strength, but if you shoot with the camera in the Clear filter position and then stop down the iris, what you're doing at that point is reducing visible light but not IR. The result can be IR contamination.

Please check to see if your IR filter is installed. If not our tech support can assist you.
 
I have the default camera settings, and my IR Filter is installed. But it seems to not be sufficient when shooting f/4 at 5000ISO w/ tungsten lights.

I am curious what brand of IR filtration people are using? And if that glass has to be removed every time you use the internal NDs.

Man this is a real bummer.
 
I have had some strange experiences with Tungsten lighting and the LT. Sometimes blue or black clothing appears reddish. I thing it has something to do with the sensors response to Tungsten light than IR contamination. I usually use an 80C filter when using the LT with Tungsten lights and that corrects the problem. It might be a case of starving the blue channel of light. Many sensors have problems with that. Strangely, LED lights that are balanced for Tungsten, like the Aputure 120t, do not exhibit the same problem. I wonder if others share that experience.
 
Thanks Ray. Good to know.

The lights that were being used were old school tungsten hot lights.

I popped by Panasonic Hollywood this morning, and we did some testing with Steve there. Although we didn't isolate the problem, and we not able to reproduce the problem with the lights they had availing, I have shared my files with Panasonic and they are sending them to the engineers for review.

I am also going to be doing aother round of testing to help isolate the issue. Perhaps its just my camera. In any event I feel like I am in good hands. Panasonic is awesome!
 
RayZan said:
I have had some strange experiences with Tungsten lighting and the LT.
Click to expand...

THIS. I'm so glad I saw this thread. Did a shoot a few weeks ago where this bit me...a blue curtain was pinkish/purple under tungsten light, and the performer's black suit definitely skewed red. I assumed maybe I had somehow had taken a funky white balance with too much minus green. If it helps at all, this was an event shoot of a stage lit by tungsten spot lights, and the curtain had tungsten spots pointing straight down from above it. Used a GH4 as a B-cam and the curtain/suit looked fine on that.

Alex, please let us know what you find out!
 
Thanks Mitch! Congrats on the new gig! I think I saw you at the CD booth at NAB NY in November, didn't get a chance to introduce myself though. You were surrounded by people every time I passed by the booth.

In the meantime, looking for an IR Cut filter...with B&H and Adorama closed until next Wednesday, any other dealers I can get a Schneider True-Cut from? Been searching and coming up empty. I don't have a matte box at the moment so I'm hoping to get a circular filter. I have a shoot next week under uncontrolled lighting and might have to balance tungsten...will this hold me over?

https://www.amazon.com/Hoya-Infrare...F8&qid=1492120084&sr=8-1&keywords=82mm+ir+cut
 
I don't know that particular filter so cannot speak to its effectiveness. I know you can buy Schneider filters from AbelCine, BandPro and FilmTools. Doubt any of them have it in stock so they would get it from Schneider. Just because it isn't on a dealer's website doesn't mean they can't sell it.
 
Curious to know what you found out Alex. I did the following test a while back when I first got the camera. The first is an Aputure LightStorm 120t led light. With color balance of 3000k. The second is an Arri650 Tungsten light with color balance of about 3300K. Notice that the LED light is actually made to be a bit warmer than the tungsten light. I like it because I can mix it with my old Tungsten lights. Notice the difference in the blue shirt after balancing both clips for a neutral WB in Resolve. That cannot be IR contamination. All setting were the same for both clips. For some reason the sensor doesn't like Tungsten lights.

Arri650_1.2.1.jpgLED_1.1.1.jpg
 
jaypass said:
Thanks Mitch! Congrats on the new gig! I think I saw you at the CD booth at NAB NY in November, didn't get a chance to introduce myself though. You were surrounded by people every time I passed by the booth.

In the meantime, looking for an IR Cut filter...with B&H and Adorama closed until next Wednesday, any other dealers I can get a Schneider True-Cut from? Been searching and coming up empty. I don't have a matte box at the moment so I'm hoping to get a circular filter. I have a shoot next week under uncontrolled lighting and might have to balance tungsten...will this hold me over?

https://www.amazon.com/Hoya-Infrare...F8&qid=1492120084&sr=8-1&keywords=82mm+ir+cut
Click to expand...

I have an 82mm version of that filter Jay. It actually works in correcting the problem but I don't think because it's IR cutting. It has a cyan tint to it and I think this is what does the job. So an 80A, B or C filter would do the same. I can lend it to you for your job if you want. I am in NYC. Cheers, Ray
 
RayZan said:
Curious to know what you found out Alex. I did the following test a while back when I first got the camera. The first is an Aputure LightStorm 120t led light. With color balance of 3000k. The second is an Arri650 Tungsten light with color balance of about 3300K. Notice that the LED light is actually made to be a bit warmer than the tungsten light. I like it because I can mix it with my old Tungsten lights. Notice the difference in the blue shirt after balancing both clips for a neutral WB in Resolve. That cannot be IR contamination. All setting were the same for both clips. For some reason the sensor doesn't like Tungsten lights.

View attachment 122720View attachment 122721
Click to expand...

Sorry. the first is the Tungsten light and the second is the LED light, hence the purple hue of the shirt in the first
 
I have a Schneider optics 680 IR-cut 4x4 filter, but it's in Chicago. I had someone post the filter to me, and it will arrive Saturday or Monday. I've also used Hoya 680 cut Screw Ons.

I got good results with both on the BMCC and Ursa Mini 4.6k, both of which REALLY struggled with IR pollution. The BMCC more so than the Ursa Mini, but those filters cleared everything up. I am curious to see how well the Schneider performs with the LT under tungsten lights. I'll be able to do some more testing once it arrives and post my results.

But here is the strange thing. Other users are reporting that they've had no problems with tungsten lights. So what does that mean? Some cameras are wonky, others not?

I am hoping that with a few user tests, the engineers at Panasonic can come up with a solution. Obviously they can't test for everything, and its' up to end users like us to report things that slip thru the cracks. But it is strange that tungsten lights, the staple of the film industry, were not taken into consideration when they were developing the camera.

The good thing is, the IR filter is easily replaced. So maybe a recall or a user upgrade can solve this problem. Hopefully, there is a remedied behind the lens. Because screw on filters and matte boxes start to feel very cumbersome once you've gotten used to the Varicam's internal NDs.

In any event, Panasonic was really helpful today. And I feel they have done an excellent job with the camera, and I'm totally down to help them however I can. I'm not mad at all.

-A
 
Ah, one other point I forgot to mention.

I did another quick test today, and it seems even with the ND engaged under tungsten lights there is still IR pollution on my camera. Some of the earlier footage I shot appeared to be ok with the ND engaged. But after reviewing the clips more carefully at Panasonic, those particular instances the garments that were more pinkish only looked better because they were being illuminated by another light source. Not the stage lights.

Keep you guys posted!
 
RayZan said:
I have an 82mm version of that filter Jay. It actually works in correcting the problem but I don't think because it's IR cutting. It has a cyan tint to it and I think this is what does the job. So an 80A, B or C filter would do the same. I can lend it to you for your job if you want. I am in NYC. Cheers, Ray
Click to expand...

Thanks for the offer, Ray! I'll let you know. I'm actually closer to Philly so it might be a little difficult to find time to meet you in NYC, but I'll keep that in mind if I have trouble finding something. Making phone calls now.
 
Alex Derrick said:
But here is the strange thing. Other users are reporting that they've had no problems with tungsten lights. So what does that mean? Some cameras are wonky, others not?
Click to expand...

That could mean that a particular "batch" of cameras shipped with a faulty filter or something like that? Once Mitch gets closer to the source of the issue, maybe we can share serial numbers with him from "clean" and "non-clean" cameras and see if there's any consistency there. It's definitely odd that we're just finding this problem now, a year after release...leads me to believe that it's something with our cameras in particular that can be repaired.

I have no doubt that Panasonic will come up with a solution ASAP. The guys in the Newark office have been absolutely wonderful to deal with.
 
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