F35 Beginners: Exposure for S-Log

JMtheDP

JMtheDP

Veteran
So, I've recently bought a lightmeter after a couple of years without (don't ask) and I have been using it with the F35. I've come to some interesting conclusions and thought I would share. Nothing is going to be particularly revelatory to those who have done some exploration of the topic, but I thought it warranted its own topic on here for any other people coming to the F35 family, especially those coming from a non-film background.

Previously, I have been exposing by eye - the technique I have used very successfully for years on my F900 with a mild gamma curve. For the F35, I always shot in S-Log but always never used a LUT to monitor.

I only ever turned the LUT on for dark scenes, thinking that for most daylight work, it just blew everything out and looked crap.

When I got my lightmeter, I started using that to meter. I rated the camera at 400 ASA, because I am a conservative type with exposure. I know this camera has stupendous highlight ability, so I wanted to play to its strengths.

But, I couldn't reconcile what my meter was saying with what the camera was saying. Everything looked underexposed, and very, very flat. Nothing came even close to clipping for a lot of the shots. Previously I would use a waveform along with my eye and try and land the scene dead-centre for exposure. However, when it came to processing the footage, any instant LUT just over-exposed everything.

Why? I was over-exposing. The F35 is truly like film. In nearly every way. I have been shooting a lot of interiors recently and the reason my waveform looked a little low and thin was the scenes were not coming even close to stretching the camera's abilities. Skin-tones go very low down, around 40 IRE, because the camera has a lot of headroom. Noise levels are "acceptable" - it isn't grain free but I don't mind a bit of noise - it is natural to me.

I was most impressed when I was exposing a scene today, in comparatively crappy English weather. I exposed according to the meter, checked my waveform. It looked fairly stingy - everything happening from 20-40 IRE. Then, I panned up to the sky. The waveform peaked around 85 or so - the camera was holding detail in a very bright sky and a very dark brick wall. Very nice. Had I exposed my "traditional" way, this would not have worked.

So, I am learning to un-trust my eyes and re-trust my meter. It is proving very interesting. For further reading, I really suggest seeing a more detailed article, with pics, by Timur Civan, below

http://timurcivan.com/2011/09/sony-f3-slog-testing/

Hope this helps some people, would love to hear opinions on this

James
 
Hi Jim,

The tendency is always to over-expose with almost any flavour of SLOG. With Sony slog2 middle grey is actually 32% IRE. It's very very low - but with slog1 (F35 and F3) middle grey is 38%. On a monitor mid-tones can appear so low that you just can't help but pop them up 2-3 stops just so you can see something. This eats away at the dynamic range and should be avoided obviously.

If you are using a light meter for exposure, which by most part is all I ever use to determine my exposure and lighting ratios, I suggest you put a grey card on your camera for 32%IRE on a WFM and then re-rate your camera to see what ISO it is when your f-stop match on your meter and iris on the taking lens. If you follow this going forward you can guarantee that your light meter is telling you when you have lit for middle grey - from there obviously its up to you if you want to vary it depending on where you want your skin tone to fall, or even depending on the skin color you are shooting.

I swear by the light meter, I don't care what anyone says, and I believe for shooting slog its become even more an important tool. LUTs can cause you to easily screw up exposure depending on the LUT itself and if you know how it is mapped to slog. ie. a REC709 LUT designed for slog will most of the time bring that 32% up to 45%. So with the LUT you'd want to see middle grey at around 45%.

I had a shoot today with the F55 and used the Alexa clone LUT by Sony called LC709-A. Even though I had the LUT enabled in the monitor, I went by what my meter told me because I knew I could trust my previous "calibration" or "camera rating".

By the way here is a handy chart with the mappings for various Sony slogs since there are now three versions of them
ScreenShot2014-02-15at65331PM_zps438a4526.jpg


For more reading on using a light meter I started this thread which turned out to be better than I thought.
If a light meter is good enough for Deakins...
 
Last edited:
Dennis

Just want to confirm something here - you said on S-Log middle grey is 32%, but the chart you show me has it at 38%, with S-Log2 having grey at 32%?

I am very much in agreement with what you have to say. Exposing with my light meter, the shots looked plain wrong on set, but getting them into my laptop they all looked much better.

Cheers
 
Sorry Jim I should know better than to write a post after a long day of shooting but I've made some clarities in my post that should make a bit more sense now. Yes slog1 middle grey is 38%, and slog2 is 32%. :beer:

There are some who will argue about using light meters for digital because they are incident (light falling on them) as opposed to reflectance (which is what the actual camera will see). This is a fair point, but if you are shooting something very white, or the scene contains a lot of white, or the scene has snow in it, then you would know to probably under-expose it 1 stop. Same with lower-key or dark scenes, or darker color skin subjects, you would know to increase your light slightly. Well that's how I work anyway.

I forget, but does the F35 have in-camera LUT support? Even if the F35 supports 1D LUTs you can create use a slog to REC709 LUT and at least that way on set you if you are looking at your monitor work with a more normal image.
 
Hi Star

The camera does have built-in LUTs and also the facility to roll-your own. After a couple of days of uncertainty, I learned to trust my meter, I rated the camera at about 400 ISO. I will be buying a sekonic chart to do a proper calibration, however.

Exposing in S-Log is tricky to get to grips with at first, but I have to remember the extreme flexibility of the F35 and the fact that it is *just like film* - even I forget that some times.

JM
 
I also want to add for anyone who doesn't believe in using a lightmeter on the F35, the manual for CINE-EI mode states the mode was explicitly designed for use with a lightmeter.
 
On the F55 I had to shoot in CINE-EI mode in order for the LUTS to actually work, kind of stupid, since on the F55 shooting in CINE-EI mode disables noise reduction.

I understand how and why I might decide to rate my camera lower, but I don't like CINE-EI mode because then it means you have to work at the cameras base ISO... and what if you don't want to or can't?
 
starcentral said:
On the F55 I had to shoot in CINE-EI mode in order for the LUTS to actually work, kind of stupid, since on the F55 shooting in CINE-EI mode disables noise reduction.

I understand how and why I might decide to rate my camera lower, but I don't like CINE-EI mode because then it means you have to work at the cameras base ISO... and what if you don't want to or can't?
Click to expand...


Maybe cine-ei is set for best performance and is important to shoot base ISO for best performace? Gain is never good maybe.
 
I think Mac said with s-log cine-ei he set meter to iso400 or 450 and shoots. It works and is simple.
 
Yeah a lot of meters won't do ISO 450, I am confident enough that the F35 handles over-exposure well enough to rate at 400. I know Dean Semler used to rate the Genesis at 640 because "he was greedy" (his words, not mine)
 
Yesterday whole day with F35 only expose by eye. Footage is ok no problems. Is better over expose or underexpose a little with F35 slog in cine?

Maybe Macgregor lightmeter system is safest?
 
Personally I'd rather overexpose than underexpose. The noisefloor creeps up quickly on the F35. If I were you I'd use the built-in LUT and a waveform monitor to check the exposure.

EDIT: Or a lightmeter, as you said. That is of course the ideal solution.
 
I read that log is better underexpose. Maybe only for F3 then.

You trust F35 ISO rating too? Mac said he only use lightmeter and nothing else to expose.
 
SJX said:
Yesterday whole day with F35 only expose by eye. Footage is ok no problems. Is better over expose or underexpose a little with F35 slog in cine?

Maybe Macgregor lightmeter system is safest?
Click to expand...

I think the answer to overexpose or underexpose ultimately depends on the scene you are shooting, and the lightmeter is just the tool itself which only really comes into play once you decide how you want to go about your exposure.

If a scene has lower contrast than the dynamic range your camera is capable of then it's not a bad idea to rate your camera lower and overexpose slightly and then adjust the levels in post so that you get a cleaner image since effectively you INCREASE the signal-to-noise ratio and DECREASE the noise. ie. Why underexpose and work closer to the noisefloor which will only get worse if you lift it in the grade?

If the scene has a higher dynamic range (perhaps even a low-key scene with high amounts of reflectivity and highlights) and you decide to overexpose you start eating away at your latitude in the highlights. So you might actually underexpose to give yourself some additional highlight protection but of course this will put your shadows and darker mid-tones into the noise floor.

So I believe it stands to reason that depending on your scene, and how much of your scene you decide to control, that you have to decide your exposure approach given the situation. Hence the "Crux of S-Log" which I've written a complete chapter on in my Exposure Guide incase anyone is interested in reading more about it. It's also why in the F65 thread I wrote how RAW will give you more flexibility in your exposure when compared to working with S-Log.

I should say that not all cameras or formats are equal, so of course it depends from camera to camera, and I will say that with respect to overexposure in general the the F35 seems to handle overexposure in a much more pleasant way over most other cameras.


SJX said:
I read that log is better underexpose. Maybe only for F3 then.

You trust F35 ISO rating too? Mac said he only use lightmeter and nothing else to expose.
Click to expand...

Also be sure to go through the process of rating the camera yourself using a grey card, even light source, waveform monitor and your lightmeter. Don't just arbitrarily use someone else's rating because your meter might not be calibrated or even work the same way they use theirs. Going through the process of rating it yourself let's you work out all the kinks and issues you might run into, so its suggested to go through it yourself if you plan to start using any meter with a camera.

Also a dedicated chapter in my Exposure Guide on how to perform the rating and work with the results you might get.
 
starcentral said:
If the scene has a higher dynamic range (perhaps even a low-key scene with high amounts of reflectivity and highlights) and you decide to overexpose you start eating away at your latitude in the highlights. So you might actually underexpose to give yourself some additional highlight protection but of course this will put your shadows and darker mid-tones into the noise floor.
Click to expand...

I think this is so with other cameras. But F35 has more range in highlights than shadows so protecting shadows maybe make more sense?

starcentral said:
It's also why in the F65 thread I wrote how RAW will give you more flexibility in your exposure when compared to working with S-Log.
Click to expand...

I saw that and was replying but didn't want hijack James F65 thread.

starcentral said:
I should say that not all cameras or formats are equal, so of course it depends from camera to camera, and I will say that with respect to overexposure in general the the F35 seems to handle overexposure in a much more pleasant way over most other cameras.
Click to expand...

Yes I think F35 is maybe different and this apply different.
 
Shadow detail is such a tricky issue too, because we can generally all agree on what a clipped highlight is, but one man's "nice shadow detail" is another man's "noisy useless muck"
 
With digital, and more-importantly, with trying to make digital look like film - I think best bet is (where needed) to underexpose and shift your latitude in the same general direction as negative stock (i.e. try to hold as much highlight detail as possible, and just accept that your shadows will drop off more sharply as a result).

Film doesn't see all that far into the shadows, so don't worry about it - get some light on the elements of the frame that need it, and let the rest crush off into blackness. It's being able to hold on to those highlights that really separates the men from the boys.
 
I do agree with Grug that lighting the shadows is the way to go if you want rich and clean blacks. Think of going about it two ways:

1.) You can keep your middle grey or skin tones where you want and only lift your shadows using lighting. Then in post push the blacks back down and they will appear crisp and have nice details without "mud". This effectively increases the signal-to-noise ratio of your shadow region without altering the rest of the image.

2.) You can just rate the whole camera lower all together (ie. so you're lifting the tones across the entire range evenly) which in turn means you're shadows are brighter, but so are your mid-tones and highlights. Later in post your bring the whole exposure down evenly across the entire tonal range. You also effectively increase the signal-to-noise ratio of the entire image but at a loss of your range in the top end. ie. highlights.

Method 1 does not eat into your highlights because you're controlling the "curve" on-set as the image goes into the camera.

Method 2 eats at your highlight latitude. (Edit: This is known as CineEI mode on the Sony's...)

Both will do the same thing in terms of retaining shadow details but one loses highlight latitude while the other requires more meticulous lighting control.
 
Last edited:
Grug said:
It's being able to hold on to those highlights that really separates the men from the boys.
Click to expand...

With F35 this seems no problem. Since I start using F35 I'm shocked with highlights. So good. Even if totally blowing don't look so ugly like all digital cameras. Maybe with F35 ETTR is best way? Think you don't need worry about highlights. Not so much.
 
You must log in or register to reply here.
Back
Top