Author Topic: Question about ISO Consistency  (Read 3679 times)

RTLdan

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Question about ISO Consistency
« on: March 05, 2014, 09:05:51 AM »
Hi everyone!
 Just curious -- I was listening to an interview with the DP of House of Cards,
and one of the questions he was asked was what ISO he shot at (on the RED Epic).
He replied, "800".

That got me thinking: In a big budget production shot digitally, are they sticking to one ISO to remain consistent in noise patterns and things like that?

 Not really sure I understand the logic behind using one iso as opposed to whatever iso the scene demands (assuming it's not overly noisy or underexposed).

Love to hear all your thoughts!
Thanks!
-Daniel

a1ex

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Re: Question about ISO Consistency
« Reply #1 on: March 05, 2014, 09:46:22 AM »
Usually ISO 100-200 has FPN + random noise, the higher ones have mostly random noise with less FPN. Maybe it matters to some people, but I'd say the difference is tiny if you expose properly.

What you should know is that setting ISO on a Canon DSLR is very different from RED or BMCC or let's say Nikon, because the DR curves are not the same (you can check the Nikon ones on DxO, not sure about RED/BMCC).

For H.264 try ML digital ISO, for RAW try ETTR. That should result in minimal noise.

On a ISO-less sensor like Nikon, assuming it can shoot raw video, you could simply shoot at the lowest ISO without worrying about it.

ItsMeLenny

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Re: Question about ISO Consistency
« Reply #2 on: March 05, 2014, 10:10:52 AM »
I've heard that the Red doesn't have an ISO. Or rather the iso isn't burnt in, the video just uses the lowest iso and records metadata of ISO being 800.
So maybe the question he was more answering was "What ISO did you expose for?"

Andy600

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Re: Question about ISO Consistency
« Reply #3 on: March 05, 2014, 10:20:49 AM »
re: House of Cards interview.

ISO choice on a Red, Alexa etc is more about keeping a uniform level of noise on all shots which is why a DOP will often still use a higher ISO even in strong light with the addition of ND filters. Cinema camera sensors have a sweet spot referred to as the native ISO which is not necessarily the cleanest ISO, but where fpn is minimal and DR is greatest. They measure DR by counting the f-Stops above and below middle grey i.e. -5 stops to +7 stops and light/expose a scene according to the ISO setting. With DSLRs we tend to choose ISO based on the available light but either practice can be used. It just depends on how big your lighting budget is.
Colorist working with Davinci Resolve, Baselight, Nuke, After Effects & Premier Pro. Occasional Sunday afternoon DOP. Developer of Cinelog-C Colorspace Management and LUTs - www.cinelogdcp.com

RTLdan

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Re: Question about ISO Consistency
« Reply #4 on: March 07, 2014, 06:49:09 PM »
Thanks guys! That makes more sense now.
Since it's just me making videos with no budget or lighting expert, I'll stick to whatever ML ISO exposes the scene properly ;).

Best,
-Daniel