When should I use a Cinegamma or Hypergamma?

workshops-275 When should I use a Cinegamma or Hypergamma?

Cinegammas are designed to be graded. The shape of the curve with steadily increasing compression from around 65-70% upwards tends to lead to a flat looking image, but maximises the cameras latitude (although similar can be achieved with a standard gamma and careful knee setting). The beauty of the cinegammas is that the gentle onset of the highlight compression means that grading will be able to extract a more natural image from the highlights. Note than Cinegamma 2 is broadcast safe and has slightly reduced recording range than CG 1,3 and 4.

Standard gammas will give a more natural looking picture right up to the point where the knee kicks in. From there up the signal is heavily compressed, so trying to extract subtle textures from highlights in post is difficult. The issue with standard gammas and the knee is that the image is either heavily compressed or not, there’s no middle ground.

In a perfect world you would control your lighting (turning down the sun if necessary ;-o) so that you could use standard gamma 3 (ITU 709 standard HD gamma) with no knee. Everything would be linear and nothing blown out. This would equate to a roughly 7 stop range. This nice linear signal would grade very well and give you a fantastic result. Careful use of graduated filters or studio lighting might still allow you to do this, but the real world is rarely restricted to a 7 stop brightness range. So we must use the knee or Cinegamma to prevent our highlights from looking ugly.

If you are committed to a workflow that will include grading, then Cinegammas are best. If you use them be very careful with your exposure, you don’t want to overexpose, especially where faces are involved. getting the exposure just right with cinegammas is harder than with standard gammas. If anything err on the side of caution and come down 1/2 a stop.

If your workflow might not include grading then stick to the standard gammas. They are a little more tolerant of slight over exposure because skin and foliage won’t get compressed until it gets up to the 80% mark (depending on your knee setting). Plus the image looks nicer straight out of the camera as the cameras gamma should be a close match to the monitors gamma.

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8 thoughts on “When should I use a Cinegamma or Hypergamma?”

  1. What is the difference between Cinegamma & Hypergamma?
    If there is no difference, please say so!
    If there is a difference, please explain!
    John

    1. Cinegammas and hypergammas are basically the same kind of thing. They achieve a greater latitude by compressing highlights by increasing amounts. Cinegamma 1 is the same as Hypergamma 4 and Cinegamma 2 is the same as Hypergamma 2.

      CG1/HG4 takes a 460% input range and compresses it in to 109% and CG2/HG2 takes a 460% input range and compresses it in to 100% broadcast safe range.

  2. Hi,

    I used both a Sony F3 with SLog built in as well as a 5D Mark III to film a dance recital. To get the videos to ‘match’, I used Marvel Cinestyle on the Mark III and Slog on the F3. However, I did not have any external recording device for the F3, and I believe the F3 is 8-bit 4:2:0 internally. Was there any advantage using SLog here? Was there something else I could have chosen in the F3 (and in the Mark III) to remain ‘close’ to minimize grading requirements?

    Thanks,

    Paul

    1. Really using SLog or Cinestyle on an 8 bit camera is pushing things. Sometimes you will get away with it, sometimes not. If exposed correctly, the amount of pulling of those limited 16 grey shades per stop will probably result in some pretty flat looking skin tones. The final result might look OK, but may have looked better if shot using a less severe gamma. You’ll never know for sure unless you had done a side by side test.

      I wish people would get over the fashionable trend of shooting flat in 8 bit. It’s fashion, it’s not actually beneficial in most cases. just because high end 10 bit (including F3 with external recorder) and 12 bit cameras can shoot flat, it doesn’t mean you should also shoot flat with an 8 bit camera.

  3. hello,

    i was testing the fs5 for the best setting (mostly interior/ambient lighting w/middle eastern skin tone levels ) that can render a truly natural colors for high end broadcast production and cant form a final opinion.
    honestly i wish i could use slog to get nicely rendered color tones that feels a bit of both, film and TV , but it seems that only CG4 can handle the low light with clean results.
    we got the new MK fujinon to achieve a clean crisp image and we are thinking to use external disk to bypass the XAVC long into HQ prores for better workflow in post . i feel that 10 bit 442 is more than enough for the job (broadcast on HD tv network) ,
    an output thru BNC the HD 10 BIT 442 to a shogun slog will do the job or a CG4?
    i honeslty do not know if slog will make a difference in 10 bit, your opinion is highly appreciated any tips or ideas ?

    1. If you shoot log you will need to grade it and that adds time and complexity to the project. Log is not a magic bullet for low light. In low light there isn’t enough light falling on the sensor so the images will be noisy no matter what you use. Cinegamma 4 works pretty well for a lot of applications and has reasonable dynamic range and works pretty well when you don’t have time to grade.

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