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Sony Alpha 7S Mark II, exposure and SLOG curve


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#1 AlejandroGomez

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Posted 24 May 2016 - 09:39 AM

Hi everybody I'm digging into the Alpha 7 SII and get some questions about exposure. As I read in some articles LOG curves are made to keep the max. data in the highlights so the correct way to expose is  ETTR mode, so about +2 stops. Will this be the correct exposure and the way to get the cleanest image possible.?

 

When you are in a low-key situation where the scene make your histogram going to the left and the shadows are all over, which is the best way to expose? Because in some tests lighting a subject with a really hard source and a lot of contrast in the image I found the picture really grainy with a lot of color noise.

 

 

Thats the same thing happens when you work with LOG C in the Alexa? 

 

 


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#2 Bruce Greene

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Posted 24 May 2016 - 10:52 AM

Hi everybody I'm digging into the Alpha 7 SII and get some questions about exposure. As I read in some articles LOG curves are made to keep the max. data in the highlights so the correct way to expose is  ETTR mode, so about +2 stops. Will this be the correct exposure and the way to get the cleanest image possible.?

 

When you are in a low-key situation where the scene make your histogram going to the left and the shadows are all over, which is the best way to expose? Because in some tests lighting a subject with a really hard source and a lot of contrast in the image I found the picture really grainy with a lot of color noise.

 

 

Thats the same thing happens when you work with LOG C in the Alexa? 

 

 

I've worked only with the A7RII, but...

 

From my experience, the "noise" from LOG mode on the Sony is largely due to in camera compression artifacts during recording.  Over exposing one stop or so helps minimize this noise, at the expense of highlight detail.  Recording LOG to an outboard recorder (even though it's only 8 bit output) in ProRes 4444 improves the situation significantly also.  On the A7RII, when applying a REC709 LUT to the live HDMI signal, I could not observe the color artifacts at normal exposure.  In the case of the A7RII, that is ISO 800.

 

There is no such issue when recording ProRes 4444 in LOG mode in an Arri Alexa.


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#3 Robin R Probyn

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Posted 24 May 2016 - 11:21 PM

The big problem is 8bit Log footage.. far from ideal.. and something you wouldn't do on the F5/55.. . slog2 is best for A7/a6300..  if its really dark and/ or not alot of DR ,Log isnt always the best curve to use.. esp in 8 bit recording.. but yes .. over exposure .. without clipping and pulling down will always minimize noise..

 

Recording Log with the Alexa is a different planet.. you shouldn't get any problems.. this is comparing a Ferrari to a skate board..


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