Shooting S-Log3 on the PXW-FX9 – Do I need to expose bright?

Having shot quite a bit of S-Log3 content on the new Sony PXW-FX9 I thought I would comment on my exposure preferences. When shooting with an FS5, FS7 or F5, which all use the same earlier generation 4K sensor I find that to get the best results I need to expose between 1 and 2 stops brighter than the 41% for middle grey that Sony recommend. This is because I find my footage to be noisier than I would like if I don’t expose brighter. So when using CineEI on these cameras I use 800EI instead of the base 2000EI

However the FX9 uses a newer state of the art back illuminated sensor. This more sensitive sensor produces less noise so with the FX9 I no longer feel it is necessary to expose more brightly than the base exposure – at either of the base ISO’s. So if I am shooting using CineEI and 800 base, I use 800EI. When shooting at 4000 base, I use 4000 EI. 

This makes life so much easier. It also means that if you are shooting in a mode where LUT’s are not available (such as 120fps HD) then you can use the included viewfinder gamma assist function instead. Viewfinder gamma assist adds the same 709(800) look to the viewfinder as you would get from using the cameras built in 709(800) LUT.  You can use the VF gamma assist to help judge your exposure just as you would with a LUT.  Basically, if it looks right in the viewfinder, it almost certainly is right.

Testing various FX9’s against my Sekonic light meter the cameras CineEI ISO ratings seem to be spot on. So I would have no concerns if using a light meter to expose.  The camera also has a waveform scope and zebras to help guide your exposure.

VF Gamma assist is available in all modes on the FX9, including playback. Just be careful that you don’t have both a LUT on and gamma assist at the same time.

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2 thoughts on “Shooting S-Log3 on the PXW-FX9 – Do I need to expose bright?”

  1. I was very surprised to read that the FX9 doesn’t ship with the Hi/Low function. I use it religiously on my 55 and FS7. Of course this is a side effect of knowing I’m exposing 2 stops over and always wanting to make sure I’m not blowing things out when outdoors. While that function would still be nice to have for peace of mind, not having to ETTR all of the time will definitely give me more peace of mind. Not having to load different exposure compensated LUTs for producer monitors is going to be so nice. Not having to sweat the highlights in bright scenes will also be nice.

    1. A workaround for no high/low key is simply to temporarily lower the EI by a couple of stops. This has the same effect as High Key. Just remember to put it back to your chosen EI before continuing to shoot. I do expect we will see Hi/Low key at some point in a firmware update.

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