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Why use iso 800


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Thanks! I think I've been using my A7Riii incorrectly in low light. I shoot everything (low light or otherwise) in slog3.cine at 800 ISO. It's a carryover from using the FS7 in Cine IE mode where the ISO is locked at 2000. I guess I figured I'd lock in at 800 ISO on the A7Riii. Time to run some tests.

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Sony Fs7/f5.. have a locked 200ISO in Cine EI mode....AFAIK.. Sony engineers decided that ISO 2000 gave the best dynamic range as judged from a mid grey level..  ie over exposure and under exposure latitude from a mid grey point .. can't remember exactly .. how many stops  either way .. its a bit different from the Arri method .. but sort of the same thing .. DR stays the same you just are cutting off from the high lights or the shadows .. by intentionally over or under exposing in the Sony EI mode.. by shifting that grey level up or down 

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Here's the most simple way to view ISO for most cameras.

If you shoot raw or log (or a log'ed RAW..) then you can view the ISO setting as nothing more than tweaking the luminosity of your image when grading. In most log/raw recordings, the ISO setting doesn't really influence what's recorded.

What counts is the amount of light, the aperture and the shutter speed.

You can try it yourself, pick up a camera, expose it for a given ISO, then don't touch at the aperture/shutter speed and record and different ISOs.

Then color correct them all (maybe using exposure compensation LUTs) to the same exposure. It's likely they'll all look the same.

The only thing that matters is whether you give the sensor enough light or not. I shoot s-log2 on my a7s 2 and the minimum ISO I can select is 1600, but most of the time I expose it at 200 or 400. Then during editing I have my exposure compensations LUTs.

You can have any ISO selected on your Alexa, like 800, and decide you don't need that much highlight protection so you can shoot at EI 50 or 100, juste like in the 1960s. And you thus need much less NDs.

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