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Banding lines at 50fps & 1/100 shutter speed?

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Martin Stanesby
Banding lines at 50fps & 1/100 shutter speed?
on Aug 19, 2015 at 9:28:48 pm

Hi,
I've come across something I don't know how to resolve.

I am filming in a hotel that has quite a yellow cast tranquil lighting throughout, not a problem. Then there is this area that has windows which let natural light in. It's a lighter area because of this, great...more light...BUT in this area I have suddenly got the banding lines?
I checked my shutter speed and fps, 50fps 1/100 shutter...i thought this should be ok. I dropped the shutter a slow as i can do manually, which was 1/60....this helped but doesn't eliminate the issue.
Has this got something to do with the mix of lighting....the artificial hotel lighting and natural light from the window? What is there left to do on a DSLR to tackle this issue?

I'm using Canon 5D mkIII

I didn't think this was an aperture issue as when I stopped down it didn't make any difference to the banding. Similarly, it had nothing to do with the volume of light as the darker area in the hotel was fine but this lighter area caused the issue???

Any help would be appreciated as we are shooting a wedding in 2 weeks and iv'e not come across this before.

Thanks

Martin


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Steve Crow
Re: Banding lines at 50fps & 1/100 shutter speed?
on Aug 19, 2015 at 11:33:39 pm

No I think it has to do with the fluorescent lighting used by the hotel and it's refresh frequency interacting with your shutter speed. It's strange that this is happening by the window with natural light but to confirm my conclusion try shooting a clip in just a normal hallway in the hotel that is not getting natural light - the banding should be much worse

Steve Crow


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Martin Stanesby
Re: Banding lines at 50fps & 1/100 shutter speed?
on Aug 20, 2015 at 6:28:46 am

Hi Steve,
Thanks for the repky.
No this isn't the case. When I got to another area of the hotel, a dimmer area, the banding does not happen. When I get closer to this area with the windows the banding gets more visible.

I'm confused.

Martin


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Warren Eig
Re: Banding lines at 50fps & 1/100 shutter speed?
on Aug 20, 2015 at 4:19:41 pm

Why are you shooting at 1/100 instead of 1/50 (for 1/48 and a 180 degree shutter angle)? Are you trying to get a more staccato look?

Warren Eig
O 310-470-0905


email: warren@babyboompictures.com
website: http://www.BabyBoomPictures.com


REEL: http://www.babyboompictures.com/BabyBoomPictures/Reels.html


For Camera Accessories - Monitors and Batteries
website: http://www.EigRig.com



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Martin Stanesby
Re: Banding lines at 50fps & 1/100 shutter speed?
on Aug 20, 2015 at 5:25:00 pm

Warren,
As per my post, i'm shooting 50fps (UK) therefore the 1/100 shutter speed, im not ahooting at 25fps, and this won't produce anything near a gritty (or staccato as you out it) effect.
For film this is better for manipulation of slow-mo effects etc. This isn't stills.

However, this is not the issue or the focal point to my post.


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Steve Crow
Re: Banding lines at 50fps & 1/100 shutter speed?
on Aug 20, 2015 at 5:42:48 pm
Last Edited By Steve Crow on Aug 20, 2015 at 5:53:01 pm

Hmmm that's strange that you are not getting the same thing in the hallway (unless they have different overhead lighting there as compared to your first location by the window)

It just occurred to me that you also say the artificial lighting is yellow-ish, I wonder if they are yellow sodium lamps but I only am aware of those being used for street lighting. Of course I guess it could also be the shade or covering of the light bulbs that is colored.

Maybe you can post a sample clip but if it looks like bands or bars of discoloration moving down the frame and then starting over at the top again it sure sounds like the fluorescent lighting issue which comes up often here in this forum. About 2-3 years ago I posted a bunch of information I found on this issue here on this forum.

You might also trying checking out Vimeo or YouTube and looking for examples of fluorescent lighting "bars" or "banding" and see if it looks like what you are getting.

I also wonder if in your color grading you push the mids and highlights a bit more towards magenta if that would counteract the yellow coloring and then seeing if or how that impacts the banding you are seeing.

Are you white balancing your camera before filming? I'm not thinking of this as the cause of the banding, only the yellow-ish cast you described.

Steve Crow


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Warren Eig
Re: Banding lines at 50fps & 1/100 shutter speed?
on Aug 22, 2015 at 4:58:09 pm

Reread your post, and still not sure why you are shooting at 1/100. I know you are not shooting stills and working in pal UK. That's why I suggest 1/50. This sets the camera's virtual shutter angle to 178 degrees, just shy of 180 degrees.

As for the banding, h.264 is 8 bit so you will see this stepping in color. If you are bold enough to install MagicLantern (I use it all the time) it shoots uncompressed RAW 14bit. 14bit= no banding.

It's easy to install and allows you to manipulate the footage a lot in post. You can shoot everything else in 8bit h.264 but the trouble shots use the RAW.

Warren Eig
O 310-470-0905


email: warren@babyboompictures.com
website: http://www.BabyBoomPictures.com


REEL: http://www.babyboompictures.com/BabyBoomPictures/Reels.html


For Camera Accessories - Monitors and Batteries
website: http://www.EigRig.com



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Martin Stanesby
Re: Banding lines at 50fps & 1/100 shutter speed?
on Aug 22, 2015 at 6:03:30 pm

Hi Warren, thanks for the reply. I would use 1/50 shutter speed if shooting 25fps but not at 50fps. In manual mode you cannot get that low anyway, 60 for is the limit, any lower and a lot of blur could enter a moving image. 1/100 should be fine at 50fps and is the optimum setting, staying here usually makes sur e you don't get banding in certain lighting....but not in this case.

Thanks for the tip about Magic Lantern.....do you think this would solve my problem by using 14 bit with Magic Lantern then?

Thanks again.
Martin


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Warren Eig
Re: Banding lines at 50fps & 1/100 shutter speed?
on Aug 22, 2015 at 6:09:13 pm

Martin,

I do think it will help. Not only is it 14bit RAW, but because it is RAW you have much more latitude in the stop, like a film Negative. You can recover more of the highlights in color correction.

You are basically shooting CinemaDNG to a monolithic file. I then process this file with RawMagic on the Mac to a folder of sequentially numbered files that I bring into Resolve to color correct. You can also bring them into After Effects with ACR and process the raw there. Once I do a grade I save to my Quicktime format of choice.

Don't change the file names of the folder RawMagic or what ever you will process the file with. Keep it the same this way you can relink at the end to the original Raw file folders for the final grade.

Warren Eig
O 310-470-0905


email: warren@babyboompictures.com
website: http://www.BabyBoomPictures.com


REEL: http://www.babyboompictures.com/BabyBoomPictures/Reels.html


For Camera Accessories - Monitors and Batteries
website: http://www.EigRig.com



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