FS7: FS7 RAW woes & data distribution between: 12-bit RAW, 16-bit RAW, & 10-bit S-Log

[Ben Scott]

People talk about ETTR as if it were one thing. And that might be true if the brightest thing in your scene is a 90% white. But what if there are multiple light sources in your scene, and in some cases you want detail (a lampshade) and in others you don’t. Or you have bright clouds in your scene, and you want them to be somewhat visible. Now ETTR can mean almost anything.

ETTR is all relative but you still need to work on your light/contrast ratios within the scene with all light sources and THEN see how mush you can push the exposure to have a 'safe zone' for the shadows without blowing out highlights. It's a balancing act.


EDIT: Sam I don't think it is flippant at all. The most important thing in our job is control of the photons. Buy a light is probably the best advice I can give to people wanting to get into this game. Buy many lights. Hire lights. Get used light. Get work lights. Get whatever you have to to be able to make enough photons hit that sensor to make pictures that can tell a story. Then you can concentrate on making it look sexy.

 

[morgan_moore]

I dont see how it is a balancing act or relative?

If denis chart is correct then you clearly have about 7 usable stops, stop down to protect the highs, and meter 7 under for your blacks, you may need to lift your blacks with lighting.

Im gonna harp on but that old digiback used nearly a van of lights.. to shoot stills! It wasn't a balancing act it was just good metering and lots of lights!

(similar to kodachrom 64 too..)

S

 

[starcentral]

ETTR provides a means to actually increase the signal-to-noise ratio in post production hence decreasing any noise beyond the camera's rated S/N ratio. But going down (pulling) is way better than going up (pushing) - on film or digital.

There are times where just shooting for 18% middle grey is going to be adequate as well but my advise is always going to be to stay away from the noise floor which means avoiding the bottom stop if you can. So you either expose to the right which I'm not a fan off because then all your clips have varying base exposures which pisses me off later in post, or you work with 18% middle grey for exposure and light your shadows to make sure they are only 3-4 stops below middle grey.

 

[Ben Scott]

It's a balancing act because within that you are also trying to protect your contrast ratios.

 

[morgan_moore]

EDIT: Sam I don't think it is flippant at all.

The flippancy is that modern production cameras in sensible modes need less light which has a radical effect on speed/cost/fluency on set.

In stills I used to haul a huge light rig.. the nikon D3 stills cam changed that very much for the better.

Incedentally I was watching london spy and considering the DR of the camera (which I assume to be an alexa) and using it on the beach.

Of course I found this.. huge control of scene DR occuring..

https://twitter.com/guyheeley/status/664728327685566465

S

 

[starcentral]

Ben, WTF did Convergent Design have to say about the signal coming out of the FS7 - surely with their expertise they would know quite easily what is going on?

 

[Ben Scott]

The flippancy is that modern production cameras in sensible modes need less light which has a radical effect on speed/cost/fluency on set.

In stills I used to haul a huge light rig.. the nikon D3 stills cam changed that very much for the better.

Incedentally I was watching london spy and considering the DR of the camera (which I assume to be an alexa) and using it on the beach.

Of course I found this.. huge control of scene DR occuring..

https://twitter.com/guyheeley/status/664728327685566465

S

I say this as a former A7s owner who has never used a flash - There will never be a time when you can't make your pictures better by having more lights on hand.

Of course when I say lighting obviously I include flagging/negative fill as well in that.

I recently bought one of them there Lastolite Skylite Rapides. Very handy both for exterior sun control and for interior diffusion of a larger source.

 

[morgan_moore]

My Hasselblad moved with 3 500W elinchroms to make a basic exposure.. kind of like assuming you cant make an exposure in 'motion' without 3 5k hmis.. thats how much light I had to use control the DR into a small enough box for the camera to function.

My suggestion is the sony raw is like that and Im not saying that is a good thing. Just that it probably works if you know the limitations.

S

 

[Ben Scott]

Ben, WTF did Convergent Design have to say about the signal coming out of the FS7 - surely with their expertise they would know quite easily what is going on?

I've had conversations off here with both Mitch and colour science chap workflow chap he put me in touch with back when I was having the magenta raw issue at the start of the year. As those conversations were private and both those individuals post on this forum I'll leave it to them if they want to chime in, but to cut a very long story short the issue really is at the Sony end of things and I think your diagram is borne out by my real world misadventures.

CD genuinely seem to work their arses off improving their products but their recorders can only work with the signal they are being fed and in the case of the FS7 it's simply not good enough for me to rely on it for the higher end gigs.

 

[Ben Scott]

My Hasselblad moved with 3 500W elinchroms to make a basic exposure.. kind of like assuming you cant make an exposure in 'motion' without 3 5k hmis.. thats how much light I had to use control the DR into a small enough box for the camera to function.

My suggestion is the sony raw is like that and Im not saying that is a good thing. Just that it probably works if you know the limitations.

S

Well this is the whole point though of this conversation though and everything else to one side, the most salient points as far as my work is concerned is

1) There are some jobs/scenes that can't be squeezed into 7 stops.
2) Sony's FS7 raw is worse quality and has much less latitude than its internal recording codec and should be avoided as much as possible
3) The 7Q is an amazing piece of kit, but it's not a miracle worker.

 

[starcentral]

I know the guys at CD do work their asses off and to some extent I would even call what they do "miracles" given the type of amazing work they do. If they say "it's the signal" then it's likely just that.

I had no idea about this "issue" with the FS7 until that Raven & FS7 thread, so I'm glad to have found out about it but feel bad for my fellow mates who invested in the FS7 with CD device. That's a lot of coin even if it gets you access to 4K ProRes, etc..

 

[broughtonfilm]

Again that comes down to being able to advertise '240fps raw to an external recorder' without it actually being massively usable.

Here's one quick still.

240fps from FS7 Raw to 7Q Pro Res. LC709a LUT applied in Premiere and and I've pulled the blacks down a touch to try and clean it up

Not sure you can make it out all that well but most of the front of her green top is a pixelated mush. As I say I've actually brought that down from being exposed higher to try and protect it too.

2 x 4ft Kinos and an Arri L7c through a diffusion frame.

EDIT: Photobucket has raised the overall brightness by about a stop...

Very natural looking curves.

 

[morgan_moore]

Well this is the whole point though of this conversation though and everything else to one side, the most salient points as far as my work is concerned is

1) There are some jobs/scenes that can't be squeezed into 7 stops.
2) Sony's FS7 raw is worse quality and has much less latitude than its internal recording codec and should be avoided as much as possible
3) The 7Q is an amazing piece of kit, but it's not a miracle worker.

My point is that you can light scenes to 7 stops.. or rather it is technically possible.. it is ,however, so impractical and gear intensive that it is unlikely to have a place in modern production.

2/3 you are probably correct

S

 

[yoclay]

Again that comes down to being able to advertise '240fps raw to an external recorder' without it actually being massively usable.

Here's one quick still.

240fps from FS7 Raw to 7Q Pro Res. LC709a LUT applied in Premiere and and I've pulled the blacks down a touch to try and clean it up

Not sure you can make it out all that well but most of the front of her green top is a pixelated mush. As I say I've actually brought that down from being exposed higher to try and protect it too.

2 x 4ft Kinos and an Arri L7c through a diffusion frame.

EDIT: Photobucket has raised the overall brightness by about a stop...

I have looked at this image and it seems to me that your problem is in post. You are shoehorning a RAW image into what is essentially a monitor viewing LUT. I wouldn't do it that way at all. You are crunching the limits of your spectrum in the shadows based on old broadcast specs. I would take the RAW file and correct it directly without a LUT in RESOLVE (not Premiere) and report back. My bet is that you will have smoother transitions in that sweater.

 

[morgan_moore]

My feeling on the jumpers girls is that the white bg should have been above clip*.. white was the intention, and then rest lit so the skin was at about 90.


I think the image would then be clean.

The light package seems small for a cove if it was that.

Can you link to a DNG?

S

*We always blast our cove to clip as it is full of cracks/dirt and other crap.

 

[Ben Scott]

This wasn't a dng. It was raw from the FS7 to Pro Res on the 7Q. Oddly, I've found this to be better than the DNGs.

It is there on the original file and the LC709a applied there is not the only thing I have looked at. Including just bringing it down by hand.

With the greatest respect this is not my first rodeo and the jumper was not underexposed by any reasonable definition of the word, other than that Sony's raw output is bulls*%t. The camera shouldn't do that and if it does, for this sort of job just use a different camera. It's beyond noise. It looks like Commodore64 graphics. I didn't know I was taking a 7-stop camera to that shoot and I would never ever have tried to shoot what I had to shoot that day on that camera if I'd known that in advance.

This really isn't a case of 'oh you should have done this or that and it wouldn't have been so crap'. This simply isn't the camera to get perfect results with a shoot like that was.

There were about 50 people that went through that setup on the day and so tolerances had to be built in for a variety of skintones and various groups of people and on a job like this you absolutely have to have the skintones right over everything else.

 

[morgan_moore]

Im sure you are right.

But as you said you have not done a bracket test.

Until someone simply treats it like an o level science experiment and shoots a scene (lit for maybe 8 on a meter) at every stop from 22 to 1.4 and then tries to equalise the files in post then the situation is not proven.

The reason I feel you may not be right are that I have seen heaps of raw video files (mainly from BMC noise moaners) that when I put them into Capture One, linear, were just a tiny lump at the left of the histogram indicating huge under exposure.

Such huge under exposure could be entirely lead not by an incompetent DP but by that DP having an inappropriate signal fed to their monitor. Simply if the file is recorded in this manner and the monitor is fed a slog signal then it will lead to disaster.

Let us extrapolate that a DP had his zebras at 60 and stopped down until a forehead highlight just zebrad then the forehead is a 256 levels, and something 5 stops lower would have 8 levels to that stop. His 5 stop scene has 256 levels in total, and 3700 odd levels of data have been disguarded/allocated to the zone from white to clip.

S

 

[Ben Scott]

I'll be completely honest, life's too short for all that stuff. Or at least mine is.

I don't mean this in a stroppy way at all, but I don't need to prove anything to anyone. I'm just talking about my use of the camera in a certain situation or two after a year of shooting it non stop in just about every condition you can think of except tropical. I totally get if you or anyone would take my findings with a pinch of salt. We all use our cameras in different ways.

The stuff above and the 3 questions below is pretty much the extent of my pixel peeping.


Is it good enough?

If not why not?

What's the best solution/workaround?



In this instance - for me - where I cannot guarantee a sub 7-stop DR but need high frame rates, well... The quickest and most elegant solution is to rent another camera.

 

[morgan_moore]

Completely agree - we want cameras we can pickup and shoot.

Sony support is minimal.

Im really just recurring how I used to battle my 2005 hasselblad and what I learned which was basically to trust nothing apart from rigid 'scientific' bracket tests; not published specs, not a light meter, not web fora advice, nothing.

The final solution was to move to a camera that 'just worked' (at a £12k loss).

S

 

[morgan_moore]

Conversely at 2000 levels in the top stop a carrot of some serious smooth roll off still dangles.

With a 6 stop scene your dark stop should still have more than 10% of the entire 709 range (32/256) only stop 7 should risk banding at 16/256 for 709 delivery

S