BMPCC4K 100 ISO setting

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HughDiMauro

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BMPCC4K 100 ISO setting

PostMon Jan 17, 2022 2:21 pm

I have an upcoming, outdoor shoot in bright sunlight. My preferred settings are video mode in 4K UHD since I'm only delivering the finished product for online, in house use. I plan on using ND filters to give me an F or T stop between 5.6 and 8. I understand my BMPCC4K has a 400 and 3200 dual native ISO but will shooting at 100 ISO give me just as good dynamic range and picture quality?
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rick.lang

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Re: BMPCC4K 100 ISO setting

PostMon Jan 17, 2022 3:42 pm

Hugh, the camera manual has a chart that will show you the effect of changing the ISO values. Going from 400 to 100 shifts the number of stops above and below middle grey but the dynamic range is the same total number of stops.
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John Brawley

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Re: BMPCC4K 100 ISO setting

PostMon Jan 17, 2022 5:24 pm

Best practice to get the most from the camera would be to leave it one of it's two NATIVE ISO's, and use ND's to correct large exposure variations.

If you set the camera at ISO100, you're not really changing anything, you're only altering a curve that's applied internally. The camera still exposes at ISO400 fundamentally.

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wemrick1

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Re: BMPCC4K 100 ISO setting

PostWed Jan 19, 2022 2:28 am

John Brawley wrote:Best practice to get the most from the camera would be to leave it one of it's two NATIVE ISO's, and use ND's to correct large exposure variations.

If you set the camera at ISO100, you're not really changing anything, you're only altering a curve that's applied internally. The camera still exposes at ISO400 fundamentally.

JB


Interesting; I read someplace where 100ISO was still cleaner than 400 even though the recovery range shifted. Too many people making guesses on the internet I would imagine. It's a shame. I would love the know the dynamics they are working with. Obviously, audio amps have become very linear and obviously these two amps are not.
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John Brawley

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Re: BMPCC4K 100 ISO setting

PostWed Jan 19, 2022 2:34 am

wemrick1 wrote:
Interesting; I read someplace where 100ISO was still cleaner than 400 even though the recovery range shifted. Too many people making guesses on the internet I would imagine. It's a shame. I would love the know the dynamics they are working with. Obviously, audio amps have become very linear and obviously these two amps are not.


All that’s happening is that setting the camera at ISO 100 TRICKS YOU into exposing “to the right” which gives you a cleaner signal shot to shot. BUT, you have almost no headroom for overexposure then.


https://en.wikipedia.org/wiki/Exposing_to_the_right

https://photographylife.com/exposing-to ... -explained

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Jamie LeJeune

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Re: BMPCC4K 100 ISO setting

PostWed Jan 19, 2022 4:02 am

How digital cinema camera sensors record light and what that means for both production and post, is all explained well in great detail in this video here:

The section on sensors, exposure and ISO is from 4:30 to 24:03.
www.cinedocs.com
http://www.imdb.com/name/nm4601572/
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Robert Niessner

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Re: BMPCC4K 100 ISO setting

PostWed Jan 19, 2022 7:46 am

If you want to create finished footage only, you are not stuck with the video mode only.
You can record in film mode and have any LUT you want burnt in.
Saying "Thx for help!" is not a crime.
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wemrick1

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Re: BMPCC4K 100 ISO setting

PostWed Jan 19, 2022 2:32 pm

Jamie LeJeune wrote:How digital cinema camera sensors record light and what that means for both production and post, is all explained well in great detail in this video here:

The section on sensors, exposure and ISO is from 4:30 to 24:03.

Great lecture! What he didn't cover was amplification. Is the output from the sensor amplified e.g. per his example an audio preamp section which amplifies the output of the mic to a signal strength that the mixer can work with, to an amplitude for coding onto storage media. Or, conversely, is the output of the sensor attenuated to accomplish the same result.

Edit::::::

Just found another great video which explained it does both, which makes a lot of sense. Below native is attenuated and above is amplified. Dual ISO is achieved by altering the bit well and still uses only one amplification/attenuation circuit. Really neat stuff.
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John Brawley

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Re: BMPCC4K 100 ISO setting

PostWed Jan 19, 2022 4:33 pm

wemrick1 wrote:Great lecture! What he didn't cover was amplification.


This is sensor by sensor dependent. Some are fixed, some are not.

Not only is there dual ISO, but DUAL GAIN versions as well. The more you look the more you'll understand that there are so many choices that go into sensor design.

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Re: BMPCC4K 100 ISO setting

PostThu Jan 20, 2022 11:40 am

John Brawley wrote:
wemrick1 wrote:Great lecture! What he didn't cover was amplification.


This is sensor by sensor dependent. Some are fixed, some are not.

Not only is there dual ISO, but DUAL GAIN versions as well. The more you look the more you'll understand that there are so many choices that go into sensor design.

JB



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