Using and Exposing for Display LUTs on Set

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Dave Perry

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Using and Exposing for Display LUTs on Set

PostFri Dec 01, 2017 4:17 am

I typically shoot film log color with no display lut. Some directors don't like what they see in the director's monitor but I assure them it will look great when colored in post. I'm so used to working that way and exposing for log. However, I want to start using a display lut on set so the director can better see what the image will look like. The EOM REC 709 lut from BMD that comes in camera is too contrasty and over exposed. If I use that LUT and expose for it, I'm afraid my footage will be under exposed in post.

What workflows are you guys using on set for display LUTs? Should I just make a LUT in Resolve that looks good based on what I expose to normally and use it in camera as a display LUT?

Also, regarding zebras, I was just trying to determine the differences in zebras on the LCD versus in the viewfinder. The viewfinder seems to display zebras post LUT whereas the LCD pre LUT. I see very little if any difference when adjusting the zebra sensitivity on the LCD but quite a bit in the viewfinder. Can anyone give me their experience and understanding of how they are set up?

Thanks.
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Jamie LeJeune

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Re: Using and Exposing for Display LUTs on Set

PostFri Dec 01, 2017 7:27 am

Dave Perry wrote: Should I just make a LUT in Resolve that looks good based on what I expose to normally and use it in camera as a display LUT?


Yes. Exactly that.
Don't force your directors, producers, and editors to view uncorrected log images.

EDIT: BTW the BMD REC709 is designed to match classic HD TV cameras, rather than to roll off all 13+ stops of dynamic range nicely into REC709. If you'd prefer to use LUTs that do include really nice rolloff, I totally recommend Kholi's set for the 4.6K:
https://www.thecampcomet.com

Dave Perry wrote: Also, regarding zebras, I was just trying to determine the differences in zebras on the LCD versus in the viewfinder. The viewfinder seems to display zebras post LUT whereas the LCD pre LUT. I see very little if any difference when adjusting the zebra sensitivity on the LCD but quite a bit in the viewfinder. Can anyone give me their experience and understanding of how they are set up?

As far as I've seen in my own use of the viewfinder, it reads the level for zebras based on whatever signal you feed it. So, if you've got the LUT turned on in camera for the front SDI port feeding the Viewfinder, it will apply zebras based on the levels in that post-LUT signal. This can be a problem with LUTs that roll off the highlights aggressively and never hit 100%, some not even 95%. I learned this the hard way and clipped a some footage on a shoot because the LUT was really rolling off the highlights and my zebras set at 95% never triggered, even though I was clipping the hell out of the signal.
This is different than the zebras on the LCD screen which are always reading from the log signal when you are recording Film mode, even if you have a display LUT turned on in the LCD.
Last edited by Jamie LeJeune on Fri Dec 01, 2017 8:35 am, edited 1 time in total.
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Denis Kazlowski

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Re: Using and Exposing for Display LUTs on Set

PostFri Dec 01, 2017 8:02 am

EDIT: Never mind, did not read completely. I'd still use a LUT box or a LUT capable monitor for the Video Village.
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Dave Perry

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Re: Using and Exposing for Display LUTs on Set

PostMon Dec 04, 2017 1:37 am

Jamie LeJeune wrote:
Dave Perry wrote: Should I just make a LUT in Resolve that looks good based on what I expose to normally and use it in camera as a display LUT?


Yes. Exactly that.
Don't force your directors, producers, and editors to view uncorrected log images.

EDIT: BTW the BMD REC709 is designed to match classic HD TV cameras, rather than to roll off all 13+ stops of dynamic range nicely into REC709. If you'd prefer to use LUTs that do include really nice rolloff, I totally recommend Kholi's set for the 4.6K:
https://www.thecampcomet.com

Dave Perry wrote: Also, regarding zebras, I was just trying to determine the differences in zebras on the LCD versus in the viewfinder. The viewfinder seems to display zebras post LUT whereas the LCD pre LUT. I see very little if any difference when adjusting the zebra sensitivity on the LCD but quite a bit in the viewfinder. Can anyone give me their experience and understanding of how they are set up?

As far as I've seen in my own use of the viewfinder, it reads the level for zebras based on whatever signal you feed it. So, if you've got the LUT turned on in camera for the front SDI port feeding the Viewfinder, it will apply zebras based on the levels in that post-LUT signal. This can be a problem with LUTs that roll off the highlights aggressively and never hit 100%, some not even 95%. I learned this the hard way and clipped a some footage on a shoot because the LUT was really rolling off the highlights and my zebras set at 95% never triggered, even though I was clipping the hell out of the signal.
This is different than the zebras on the LCD screen which are always reading from the log signal when you are recording Film mode, even if you have a display LUT turned on in the LCD.


Thanks Jamie. I've used some of Kholi's LUTs in post before. It's been a while though. I'll check out his display LUTs also.

Regarding zebras. Thanks for the warning and you've also confirmed what I suspected.
BMUM 4.6k PL, BMPC 4K, BMPCC
----------------------------------------------
Dave Perry Cinematographer LLC
Director of Photography • Editor • Digital Film Production
1111 Shenandoah Ave. NW
Roanoke Va. 24017
540.915.2752
daveperry.net

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