Thread: Rating Sony FX9 at Below Base ISOs in Cine EI For Cleaner Shadows

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  1. #1 Rating Sony FX9 at Below Base ISOs in Cine EI For Cleaner Shadows 
    Coming from the Fs7, in Cine EI, I always rated the camera below the base ISO, resulting in a well exposed image in the viewfinder, and an over-exposed image on the MXF file in post. When the exposure is brought back down in post, the shadows are much cleaner, and less blotchy than if I shot at the base ISO.

    While the FX9, is great in low light, and much better than the Fs7, I have found that using a similar method, of rating the camera at a lower than base ISO, does result in much cleaner shadows and dark colors of the frame, that are less blotchy. Iím wondering if anyone else has tested this out and used this method as well.

    With the FX9, you have to go about it a little differently than the Fs7. In Cine EI, in order to access the lower ISOs, you have to Internal Record the LUT, except the LUT that you choose is SLOG3. Internally recording an Slog3-LUT seems to be the same as shooting Slog3 without Internally Recording a LUT. This allows me to drop the ISO to say 500 or 320, thus opening up the iris, and exposing the sensor to more light. With this method, the dark shadows end up much cleaner than if it were exposed at 800, and since the Slog3 LUT is baked in, what you see in your viewfinder is exactly what you get in post, so no correction needed, like when you rate the Fs7 at a lower ISO (because the Fs7 doesn't offer an Slog3 Lut).

    Iíve also found that rating the 4000 Base ISO lower, say at 2000, gave a cleaner image than 800 at the Base 800.

    Again, I know the Fx9 is pretty clean already, but I add grain in post, and do not like what happens in the shadows on these Sonys, at the base ISOs.

    Iíve never seen anyone write about this anywhere online, so I wanted to see if anybody has a similar experience.
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  2. #2  
    Moderator Phil Holland's Avatar
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    Quote Originally Posted by Johnathan Smith View Post
    I’ve never seen anyone write about this anywhere online, so I wanted to see if anybody has a similar experience.
    Heh. Welcome to REDuser Johnathan. I think I've been writing about this for a bit over 10 years here, certainly longer elsewhere. This is indeed how digital cinema cameras actually work "most of the time".

    A Base ISO is just a recommended starting point from manufacturers, often that is the approximate tonal range where you have about equal stops above and bellow 18% Gray. Lowering the ISO will weight more tonal information dedicated to the shadow areas which in effect creates a cleaner shadow, with the only negative is you are losing potential stops above 18% gray in the highlights. The flip side is a Higher ISO will weight more tonal information in the highlights at the cost of noisier shadows.

    This should help visualize what's going on:

    Quote Originally Posted by Phil Holland View Post
    All of these cameras have a Total Captured Dynamic Range. Your ISO Rating is mostly moving your 18% Gray "lump" around within that range. Some cameras have internal noise reduction, which helps in higher ISO situations, but that does come at the cost of pixel information both in detail and in color. Digital Cinema Cameras tend to not or "not very much" do that as they are focused on the maximum amount of image information possible for a given sensor.

    Hope that helps.
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  3. #3  
    (Sorry if this is a double reply, I don't see the reply I just posted). Thanks for the quick response. I was mainly wondering why I haven't seen anyone talk about this specific to the FX9. I've seen people say rating the camera lower is not needed, because it's so god in low light, but I have noticed a benefit. Also, in Cine EI, there's that added unusual step to even access the lower ISOs, of Internally Recording an Slog3 LUT (which I've never seen before on the Fs7 or the a7sii). I was just wondering if any other FX9 owners shoot this way, or even knew you could access the lower ISOs in Cine EI by baking in an Slog3 LUT. I just wanted to see if there was any downside happening I might not be aware of.


    QUOTE=Phil Holland;1902515]Heh. Welcome to REDuser Johnathan. I think I've been writing about this for a bit over 10 years here, certainly longer elsewhere. This is indeed how digital cinema cameras actually work "most of the time".

    A Base ISO is just a recommended starting point from manufacturers, often that is the approximate tonal range where you have about equal stops above and bellow 18% Gray. Lowering the ISO will weight more tonal information dedicated to the shadow areas which in effect creates a cleaner shadow, with the only negative is you are losing potential stops above 18% gray in the highlights. The flip side is a Higher ISO will weight more tonal information in the highlights at the cost of noisier shadows.

    This should help visualize what's going on:



    All of these cameras have a Total Captured Dynamic Range. Your ISO Rating is mostly moving your 18% Gray "lump" around within that range. Some cameras have internal noise reduction, which helps in higher ISO situations, but that does come at the cost of pixel information both in detail and in color. Digital Cinema Cameras tend to not or "not very much" do that as they are focused on the maximum amount of image information possible for a given sensor.

    Hope that helps.[/QUOTE]
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  4. #4  
    Senior Member Adrian Jebef's Avatar
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    JS yer on to it. We do this with the Venice as well.
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