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.
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
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.