For a Low Light shoot with FX6 / FX9 - best ISO and Color profile settings?

[Grug]

LUted or not, you must have some IRE target in mind for the underlying S-LOG or are you just judging by how it looks. What is your threshold?
On the rare times that I use a monitor LUT, I just have to know where the whites need to land with the LUT in order to hit my 72 IRE target for the underlying S-LOG being recorded. It's just a simple adjustment of my zebra levels.

It's not something I particularly quantify in terms of IRE %, I just use Exposure Index the way it's intended - you're shifting middle grey up or down, so with overexposure I'm just factoring in 1-2 stops less highlight headroom, and that's basically it.

And given that I'm mostly using high-base ISO in low-key situations, it's normally only things like street lights clipping out that I need to worry about. For insert shots (where it's handy for stopping down for deeper focus) those shots are normally all about the mid-tones, so the thinner highlights aren't a big issue there either.

[Doug Jensen]

I've been monitoring with a LUT applied on output, so the waveform only tells me the LUTted IRE levels (so with the camera set to 3200 EI, 6400 EI or 12800 EI - nothing changes waveform wise, the values are measured based on the EI value, not the underlying base ISO mode). Plus I'm still a light meter guy, so for the most part I just set that to the relavant ISO and meter accordingly.
.

LUted or not, you must have some IRE target in mind for the underlying S-LOG or are you just judging by how it looks. What is your threshold?
On the rare times that I use a monitor LUT, I just have to know where the whites need to land with the LUT in order to hit my 72 IRE target for the underlying S-LOG being recorded. It's just a simple adjustment of my zebra levels.

[Doug Jensen]

Glad I'm not alone. :^)

You're definitely not alone. Those two buttons are too close.

[Grug]

So, that begs the question, at what level would you expose white if you are overexposing by two stops? I'm aiming for 72 IRE as my "normal" exposure, which you might consider overexposure. We might not be so far off from each other.

I've been monitoring with a LUT applied on output, so the waveform only tells me the LUTted IRE levels (so with the camera set to 3200 EI, 6400 EI or 12800 EI - nothing changes waveform wise, the values are measured based on the EI value, not the underlying base ISO mode). Plus I'm still a light meter guy, so for the most part I just set that to the relavant ISO and meter accordingly.

The only real issue I've had with this method, is metadata passthrough. Having shot with the FX6 mostly recording to Prores Raw, there hasn't been reliable metadata passthrough, marking the high-base clips clearly as 3200 EI or 6400 EI.

Potentially this may have been fixed with the most recent firmware (for both the FX 6 and the Atomos Ninja V) but I haven't tested that yet.

To-date though, it's certainly been one of the reasons I've despised the current Prores Raw workflow with the camera.

[stewhem]

Also, if you're using LUTs you could try the Arri one. It gives similar results but with slightly less contrast, which might help with a low light shoot. I don't see any increase in noise with the Arri compared with the Sony.

[JimmyMcV]

Glad I'm not alone. :^)

[stewhem]

Glad the shoot went well apart from the WB problem. I did that myself on the first shoot I did with the FX6. It was a simple head and shoulders interview with minimal lighting but I pushed the same button you did and gave myself some tricky post work. And I agree with you about the FX6 colours. My previous two cameras were Canons and I find the FX6 to be more accurate to what you’re shooting

[JimmyMcV]

Shoot is complete. It was wild. We ended up shooting 100% HIGH BASE, up a stop (so EI at half). There was simply not enough light for low base. At first glance, it looks great with the Sony 709 LUT applied!!

But, my sad story is that I screwed up my cam's white balance. This is only my second shoot with this cam and I pressed the wrong button at one point. I meant to press the push auto button to temporarily bring in autofocus and instead I pushed the button below it for Auto White Balance. And then in my panic I didn't hit "cancel." 20 seconds later, not knowing anyway to get back to what I had -- it would have been nice to have an UNDO button -- I basically just dialed in the white balance to about the same temperature number.
But it doesn't look the same, folks. I must say, the footage before the white balance eff-up looks GORGEOUS! So my first task is to try to color correct to get back to how it looked before the mishap. I'm going to move this discussion about my white balance screw-up to my other thread that deals with matching cameras.

Thanks for everyone's input.

[markfpv]

Perhaps your workflow in post is where we differ. Are you doing proper grading in Resolve or just dumping a LUT on it in your NLE?

I'll just add that - if you do use Doug's methods for exposure - and are shooting broadcast interview or b-roll - then "dumping a LUT" should really be the only thing you need to do (so long as you've created that LUT with the offset for your exposure method - which can / should be done in resolve.)
I like to grade creatively - and mix it up occasionally - but if you follow very stringent methods for exposing and your lighting ratios and keep to them on set - I find that a well created LUT can be used on many a project without having to do any extensive "grading".

[drboffa]

I've posted this before, but if anyone is curious to see LO vs HI at exposure intervals you can check this out (marks 2:15 and 4:29 for the Lo/Hi footage):

I was going off Sony's recommended exposure levels (61 or so IRE for white) for "base" exposure, which I think most of us would agree is too low (certainly for HI base ISO).

To my eyes, if you're exposing a stop or so brighter than the "recommended" levels the footage should cut together seamlessly. And it's probably fair to say that rating the camera at 6400 in HI base—or exposing white at 70ish—is more appropriate for "correct" exposure in normal situations (i.e., interviews).

Having said all this, the fact that we can have discussions about clean exposures at 12,800 ISO is pretty fantastic

[Doug Jensen]

I don't really ETTR in the sense of exposing as hot as possible without blowing out. I think that the tonality/gradient/color really suffers if you push your values too high and then bring them down.

I know this thread is about S-LOG, but you have summarized my complaints about S-Cinetone. In the broadcast world, bright whites should typically hit around 90 IRE, but the tonality/gradient/color really suffers at that level and is difficult to correct in post.

[Doug Jensen]

BTW, i have actually done my own testing in 5 IRE increments from 60 to 95 IRE. Graded and analyzed in Resolve on my scopes and OLED monitors.

[ahalpert]

On the FX6, I started at 68 but have gradually moved up to 72. I also don't consider that ETTR. That is just hitting my target.

I don't really ETTR in the sense of exposing as hot as possible without blowing out. I think that the tonality/gradient/color really suffers if you push your values too high and then bring them down. And I don't care that much about a little noise anyway. But on the a7siii I definitely expose differently for high base for the sake of getting better, cleaner shadows

[Doug Jensen]

But one concrete difference is that Grug says he sets a different target for 12800 vs 800 while Doug says he sets the same target

Yes, that is correct. Same target for either one.
If I was to push HIGH base even farther, that would put it up in the high 70's or 80's and there's no way that is going to provide better results in post. S-LOG is a curve so going too high is a mistake.

[ahalpert]

But one concrete difference is that Grug says he sets a different target for 12800 vs 800 while Doug says he sets the same target