F3: Using S-Log

thefilmaddict

thefilmaddict

Veteran
We updated our F3 firmware and now have S LOG as a picture profile. We are just recording to our internal sxs cards (no external recorder). What's the proper way to expose for s-log to get the most dynamic range?

Thanks!
 
Honestly, I would not shoot SLog internally to the cards. The 35Mbps 4:2:0 footage just can't hold up to any significant grading beyond basic color correction.

I would definitely say try it and see if you are pleased with the results. A very simple guideline is to expose a gray card at 38%. The spot meter is a good starting point.

Ned Soltz
 
Thanks, Ned. So for those of you using an external recorder to get a less compressed image, which one are you using? Is Sony the only one who makes it?
 
Regarding exposure there are lots of threads here on the subject. Mainly set your middle grey for 35-38% or use a white card and set it to 65-70% IRE. You can easily use the built in spot-meter of the F3 to do this.

Ned is right that the more bits you have for slog the better, but I've shot quite a few projects to slog to internal cards even though being advised against it and as long as you are controlling your scene contrast and applying a simple de-slog in post and some basic color correction it "can" work out fine. Also remember that pushing in post increases noise, pulling in post reduces it. The biggest downside with less bits is dithering and risk of posterization or banding in certain parts of your image. So far, with the F3 I have not seen a lot of evidence of this shooting primarily to sxs for most projects.

I'm not saying 8-bit is as good as 10-bit I'm just saying that in many cases the differences may not be distinguishable in your final product but individual results will vary obviously depending what you shoot. Also I notice with the XDCAM EX codec now that I am able to compare it to XAVC on the F55 that the F3 has "finer" noise/artifacts than XAVC when you pause a frame and zoom in extremely. XAVC to me so far seems more "mpeg blocky" whereas XDCAM EX reminds me of the kind of little fuzzies you see on DCT codecs when really looking.

Anyway, I will send you a few links to work of mine that was shot in slog to sxs cards then graded for you to see. (Please don't mind the directing :happy:)

BTW: Here is one quite extreme case where I pushed the 8-bit slog image really far in post and the final image did have some fluttering noise in it, but it was hard to know if that was caused by the limits of 8-bit or 6400 ISO under very poor light quality (sodium vapor).

8-bit slog at 6400 ISO under sodium vapor lighting (yuck):


A bit of post. The highlights in background were obviously not fixed but could be toned down further in post.
 
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Here is full size 1920x1080 jpg also shot in slog to sxs. You can see a lot of dithering between skin tones on the arm, chest, forehead, and a lot of dots on the wall between the back of the bed and chair. 10-bit would have made smoother gradients between all these tones for sure. But also remember when these frames are in motion these types of "artifacts" can be tough to spot.

OnlyOne02.jpg
 
Appreciate Dennis' more detailed response. I just wanted to post something quickly as I was multi-tasking at the time.

As far as recorders, I use the Pix240. We have a number of users on this forum who like the Samurai. The Hyperdeck Shuttle for $345 plus SSD is also an excellent option giving you the choice of uncompressed, ProRes or DNxHD. I still maintain that you will see the full benefit from SLog using a 10bit 4:2:2 codec at a minimum.

Ned
 
hey,
i'm using the samurai. it works very well -especially falsce color is a great feature ...
though i'd wait for NAB for i think atomos will update to version 2...
the pix is great for their mic preamps and it's supposedly built like a tank...

regarding 8 bit vs 10bit:
my impression is that the SdiA output give you a touch more info in the darks/blacks. this output
doesn't run through all the internal processing when used with the slog option.

'though i have to admit that recently i started replacing the samurai with my new smallHD Oled mounted
with a solid camera evf mount on not so critical jobs. i bought these for i want to upgrade to an f55 in time and came to love
the detail of info/picture you get looking into the oled display. this display helps a lot judging exposure
and therefor might be worth staying in 8bit ( which i don't find a bad codec at all)

funny to hear that the xavc is macroblocking worse than xdcam-ex...
 
I'm with Ned and Dennis - if you're going to shoot SLOG (which is the only thing you should shoot for non-ENG shooting if you're using an F3 IMO) spend the extra couple of hundred bucks for a hyperdeck shuttle 2.0 (or a PIX or Samurai if you want something more fully featured).

The Hyperdeck is $300 odd dollars, and allows you to get all that 10-bit goodness out of the camera so it really does make a difference.

If your budget can't stretch to a recorder just yet - download AbelCine's "AB_SLOG" picture profile. It's a customised SLOG picture profile that crushes the blacks a bit and brings some contrast and saturation back into the SLOG image - which makes grading 8-bit 4:2:0 footage a lot more achievable.
 
I agree, but when seen in motion it is quite different.

But is what we're seeing in that image example truly a limit of "8-bit" or are there other factors at work there? noise, color space, under-exposed image boosted in post, etc.. ??
 
Maybe it is better explained this way;
8 bit or 512 shades of color or 512x512x512 (RGB) of color = 134,217,728 shades of color
10 bit or 1024 shades of color or 1024x1024x1024 (RGB) = 1,073,741,824 shades of color
Trillion vs. Millions shades of color means a lot more manipulation in the color correction.

So I really screwed this up, let me try again.

8 bit or 256 shades of color (not 512) or 256x256x256 (RGB) = 16,777,216 shades of color
10 bit or 1024 shades of color or 1024x1024x1024 (RGB) = 1,073,741,824 shades of color
Billion (not trillion) vs. Million shades of color means a lot more manipulation in the color correction.

Next time I'll ask Dennis to review my math before posting, sorry.
 
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Definitely give shooting with slog to the cards a go. At odds with other posters, I have got great pictures this way. It's certainly better shooting with slog than withot. Honestly, the results are outstanding, especially with skin tones.

I've experimented with onboard recorders but given my situation of shooting run-and-gun documentary as a one person crew - and that means directing subjects, recording sound, anticipating subjects' movement, shooting up to 60 set ups a day - the extra 1kg weight and worry over another bit of gear isn't for me on these shoots.

Shooting slog to sxs on this project was a blessing New Land, New Life - YouTube I was working with lots of African refugees in available light and there was never a lot of set up time and yet the images looked so beautiful and natural. But be cautious with your exposure AND your colour balance.

I've been using Resolve and Color to grade but recently took up Colorista to grade so I don't have to round trip from FCP7 (which I still love and use). The only time I've had issues shooting slog to cards has been with very low contrast scenes. Otherwise, the slog profile is a great bonus.
 
Afterglow said:
Definitely give shooting with slog to the cards a go. At odds with other posters, I have got great pictures this way. It's certainly better shooting with slog than withot. Honestly, the results are outstanding, especially with skin tones.

I've experimented with onboard recorders but given my situation of shooting run-and-gun documentary as a one person crew - and that means directing subjects, recording sound, anticipating subjects' movement, shooting up to 60 set ups a day - the extra 1kg weight and worry over another bit of gear isn't for me on these shoots.

Shooting slog to sxs on this project was a blessing New Land, New Life - YouTube I was working with lots of African refugees in available light and there was never a lot of set up time and yet the images looked so beautiful and natural. But be cautious with your exposure AND your colour balance.

I've been using Resolve and Color to grade but recently took up Colorista to grade so I don't have to round trip from FCP7 (which I still love and use). The only time I've had issues shooting slog to cards has been with very low contrast scenes. Otherwise, the slog profile is a great bonus.
Click to expand...

So are you using the histogram to gauge exposure?
 
It's interesting how different people have different ways of working. Histograms are really designed to be used for still photographers and they give me absolutely no useful information. On the other hand, Zebras always have been and always will be the only tool I need to nail the exposure perfectly everytime. Different strokes for different folks.
 
Doug Jensen said:
It's interesting how different people have different ways of working. Histograms are really designed to be used for still photographers and they give me absolutely no useful information. On the other hand, Zebras always have been and always will be the only tool I need to nail the exposure perfectly everytime. Different strokes for different folks.
Click to expand...

The Sony Histogram does tell you right away if your clipping or crushing, also once when I was on a shoot the lighting company was using magnetic ballast for their HMI's, the histogram was flickering on the top edges warning me to correct, I could see it in the histogram but not see it on the field monitor outside. Just the other day when I was using some new ALZO 85 watt florescent lights in china balls to bring up the lighting in a room the histogram again told me I had flickering from those lights visible in the background. Both times I was able to correct using the ECS shutter.
 
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