F3 FS7 F5/55 gamma curves

Boat Slog

I became a big fan of the Sony gamma curves on the Sony F3 when I wasn’t shooting in slog. Most of the time slog requires meticulous exposure, some form of a monitoring LUT to satisfy video village, and a post-production colourist who has experience working with it to make it shine. Myself along with many others have found that working with slog without having the experience can be like opening pandora’s box. In some cases and depending on the project I sometimes find it easier to use cinegamma curves – but knowing which one to select also requires some further understanding of each curve.

On the Sony F3 as of firmware update version 1.4 the slog gamma curve became available through the picture profile settings. Previously it had been a paid upgrade as part of the RGB upgrade upon initial release. Since January 2014, slog2 and slog3 are now available as default slog curves available on the Sony F5 and F55.

Here’s some handy information on the various cine gammas available for the Sony PMW F3, F5 and F55 CineAlta cameras and how they may be useful depending on your scene.

Sony F3

Standard Gammas:
STD1 DVW: DVW camcorder equivalent
STD2 ×4.5: ×4.5 gain
STD3 ×3.5: ×3.5 gain
STD4 240M: SMPTE-240M equivalent
STD5 R709: ITU-R709 equivalent
STD6 ×5.0: ×5.0 gain

CINE1: This smoothes the contrast in darker areas and accentuates gradation changes in brighter areas, for a calm and quiet effect (F35 HG4609G33).
CINE2: This gives almost the same results as CINE1. Select this when you wish to obtain 100% video signals for editing or other purposes (F35 HG4600G30).
CINE3: This emphasizes the contrast between light and dark more than CINE1 and CINE2, and also accentuates gradation changes on the black side.
CINE4: This emphasizes the contrast in dark areas more than CINE3. Contrast in dark areas is weaker and contrast in bright areas is stronger than STD curves.

My comments and notes on the F3 gammas:
The Standard Gammas are good for quick turn around of video files but produce a very “video-like look” and offer a very limited dynamic range response of 7-8 stops. I have always avoided shooting with standard gammas on the F3.

Using Cinegammas is where you can really start improve upon that baked-in look of your image and start giving yourself some flexibility in post for grading and color correction in your NLE. Your dynamic range increases to between 11 and 11.5 stops. It’s also great if you don’t plan to color correct or grade because it fits more dynamic range from the scene into the final image. For quick turn around shoots I always use Cinegammas.

(Note: the values below are from actual measured values using light meter, grey card and waveform monitor which may vary slightly from Sony values listed in their manual. As always perform your own tests with your full camera setup to determine your own values.)

CINE1 – Great for sunny day or scene with wide range of contrast and particularly lots of highlights or hot sources. Up to 109% IRE with middle grey at 40% IRE.

CINE2 – Same as Cine 1 but clipped at 100% IRE. Middle grey is between 35-40% IRE.
CINE3 – Middle of the road gamma curve. Up to 109% IRE.
CINE4 – Good in lower light scenarios, for example a scene which might have pools of dark patches or shadows but still has decent mid-tones and highlights. Middle grey is placed around 55% IRE.

slog – Increases the overall dynamic range of the F3 to 13.5 stops. Use for smoothened skin tone and highlight renditions and less of a “video look” and more of a “film look”. Requires professional colourist and grading for best results. Very easy to over-expose and exposure should be done meticulously according to the specifications for slog. On a waveform monitor middle grey is 38% and a white card would read 65%. Anything over 65% to 70% in slog should be where your highlights are placed if you want a more filmic look. Over exposure will result in a more traditional video REC709 look.

Below are the mapped values for slog as well as the code values in both 8-bit and 10-bit representation. What this illustrates is just how much the allocation of data bits are equalized throughout the entire tonal range of the sensor.

Sony FS7, F5 & F55

Standard gammas:
STD1 – DVW camcorder equivalent. Has lowest slope near black (for low noise and black-crushing).
STD2 – x4. Somewhere between Std1 and Std3
STD3 – x3.5
SDT4 – 240M
STD5 REC709 – Rec709 is the most commonly used gamma; it’s the default HDTV standard gamma.
STD6 – x5.0

HG1 – 3250G36 Good for low-light: brighter mid-tones.
HG2 – 4600G30 Where extra dynamic range is more important.
HG3 – 3259G40 Good for low-light: brighter mid-tones.
HG4 – 4609G33 Where extra dynamic range is more important.
HG7  – 8009G40 800% range. Good for low-light: brighter mid-tones.
HG8 – 8009G33 800% range. Where extra dynamic range is more important.

slog2 – Maximizes the response from the sensor and increased the overall dynamic range of the camera to 14 stops. This gamma requires professional grading and coloring in post in order to produce the highest quality images from it. On the Sony F5 & F55 cameras slog2 places middle grey at 32% and a white card would read 59%.

slog3 – This curve is more in tune with the response of the cineon curve and raises the lower black tones slightly. The middle grey is mapped to 41% and a white card mapped to 61%. This curve is somewhat more industry standard and common in various post production workflows.

My comments and notes on the F5 & F55:
The standard gammas give you a perfectly legal signal with blacks at 0% and white clipping at 100%. The standard gammas tend to give you a video-look straight out of the camera and do not offer a lot of room in grading without getting destructive to the images. I avoid shooting with standard gammas and default to one of the many hypergammas. Standard gammas only yield 7-8 stops of dynamic range.

The hypergammas (same concept as cinegammas on the F3) allow the camera to capture a higher dynamic range (11 to 11.5 stops) which in post will also give you more room if you require grading. I typically use HG4 or HG7 based on the scene lighting conditions and contrast ratio.

The slog curves still remain the best  method of producing the highest quality results from the camera by maximizing the dynamic range and tonal reproductions from the sensor – however as indicated a professional and experienced colorist is required to truly bring the log images “back to life”. With the F5 and F55 you can get up to 14 stops dynamic range by using slog2/slog3.

Below are mapped values for slog2/slog3.

  1. Tony KoeselerTony Koeseler01-11-2017

    Just curious. For the Cine 1, that is, F35 HG4609G33). I thought the G33 meant that middle gray was at 33 IRE, not 40.

    • Dennis HingsbergDennis Hingsberg01-13-2017

      Sony’s Cine1 on many of it’s cameras are said to be 33% IRE in the manuals but on a waveform monitor I’ve always found it substantially higher when testing, closer to 40 but probably more like 36-38%. Typically when using cinegammas with a low middle grey it means the image should technically appear dark in the viewfinder when exposed “properly” for that curve. The tendency however seems to be brighting the image so it looks “proper” on the viewfinder but in fact this is incorrectly exposing for that gamma curve. If you shoot proper with 33% as your grey value you will un-doubtingly have to increase exposure of the mid tones for the image to look right, if you shoot with Cine1 at 40% however you push up the highlights slightly but the mid-tones then become more exposed properly without having to be adjust later in post. Which way you decide to go depends on circumstance none the less. Thanks for your comments!

  2. NonnoNonno04-29-2017

    Hi, Id be greateful for your help, related to your article. I shoot with the a6300 in cine4 gamma and would like to use a coro chart in davinci resolve. However resolve doesnt offer cine4 to chose as a input gamma setting. From your experience, which gamma curve would be closest? Any hints are highly apprechiated. best, Nonno

    • Dennis HingsbergDennis Hingsberg06-21-2017

      Your best bet might be to create and use a gamma converter on your footage or input LUT so you can get resolve to match. This LUT calculator by Ben Turley will do the trick https://cameramanben.github.io/LUTCalc/

  3. KevinKevin08-06-2017

    I’ve bought your guide and like your style, that is, using a light meter and exposing to middle gray, skin tones, versus to matte white. I’ve read your forum posts and found them very helpful. I just read an article by Art Adams and it has me totally confused at this point. In his article, he states that he always exposes middle gray to 41.7 IRE and that where middle gray is on the gamma curve is informational only, telling you that perhaps more or less of the dynamic range is being shifted from the highs to the lows. Art says, ” This doesn’t mean that you should expose middle gray any differently; all it’s saying is that Sony has moved 1/3-1/2 stop of dynamic range from the highlights to the shadows, which stretches out the highlights a little and gives them more contrast.”

    But I thought that you were supposed to expose to what the middle gray level was for the curve, so that if hypergamma 3 was at 40 IRE, you exposed to 40, but if HG4 was at 33, then you exposed middle gray to 33 IRE.

    Can you help me understand what I’m missing? Thanks so much.

    • Dennis HingsbergDennis Hingsberg09-13-2017

      Hi Kevin, sorry I did not see your post here until now. It got caught in a new spam filter and I’ve been going through it looking for stray messages. Thanks for reading the blog and the exposure guide, hopefully you found it both useful and helpful.

      I don’t think Art meant that he always uses 41.7% IRE no matter what curve he selects, but I could be wrong. I’d have to read the article and see.

      You can place middle grey where ever you like for any particular gamma curve. You might do this in order to give yourself more range on the top of the bottom. So for example, you might lower your exposure slightly to give yourself that extra range on the top. Perhaps you are shooting a bright scene with a lot of whites and reflections. It wouldn’t make sense to open your iris and increase exposure as then there could be more potential for parts of the image to clip resulting in a loss of detail. So in essence you moved where you placed the middle grey point. (If you had a grey card in the scene while you increased of decreased exposure you would see it go up or down on a waveform monitor wouldn’t you?).

      Sony has mapped out some of the gamma curves differently. Mainly where middle grey sits in relation to black levels and white levels. Without even adjusting exposure, as you flip through the cine gammas for a given scene you will notice something. The image may get a bit brighter or darker, contrast will be increased or decreased between black and grey levels, and between grey and white levels.

      In a dark scene, maybe an interior without a lot of light you want to expose for white and not clip your highlights, but the room is so dark that it would be nice to give a small boost in the shadows or mid-tones… well that’s what cine4 does because middle grey is mapped the highest from all the other gamma curves. For a very bright scene middle grey doesn’t need to be boosted, there is plenty of light so it’s mapped quite low and it helps us balance a sunny scene quite easily.

  4. KevinKevin08-06-2017

    You know, I think I finally figured this out. I guess I was getting confused by thinking that the gamma curve resets middle gray versus re-mapping it. So, if you follow the fundamentals of proper exposure, that is, using the appropriate ISO, aperture, and shutter, often you will get a proper exposure. The problem and confusing thing is that the camera is monitoring the output side, so with a curve applied, it can look like something isn’t right. And to add further complication, some curves benefit from overexposure, which is then, in essence, resetting middle gray so to speak. It is also weird because you can use the output side (the wf monitor, viewfinder with mlut) to reverse engineer your way to a proper exposure, but middle gray is still where middle gray is supposed to be on the input side of the equation.

  5. MauriceMaurice09-14-2018

    Hello and thanks for this great informations
    A question: For made one shooting for one fireworks with one FS7, with a biggest range between the black to the white. The HG8 it’s better? For take every detail, color, extra black and ” hyper white?
    Thanks for your help and sorry for my bad English,
    Maurice from Switzerland

    • Dennis HingsbergDennis Hingsberg09-15-2018

      I agree ARRI color science is second to none. You do know that Sony has released a 3D LUT that to take slog3/sgamut3.cine to Venice color? It’s available on my 3D LUTs page, just use the search on the right side of any page. Cheers

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