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Stop shooting LOG Footage
  • MikeLinnMikeLinn

  • 13 Replies sorted by
  • BernieBernie

    Hmm, he's a little bit loose with the lingo ie. Confusing bit rate with bit depth. Argument that shooting log makes your footage noiser isn't valid, unless you underexpose the image and bring it up the shadows. If you expose to the same stop, you are simply reducing compression that might occur in the shadows due to a picture profile. The noise was always there in the first place, it just got compressed out of the image , along with any details.

  • radikalfilmradikalfilm

    I noticed the confusion too. There is a point to be made though for bitrate as well, at least as a 2nd order concern. While Log needs 10 bit to work (boffins figured out a minimum 9 1/2 bits), 422 color sampling needs double the bitrate vs 420. I think his tl;dr was don't shoot 8 bit 420 Log, and evaluate your actual exposure needs even if you have 10 bit 422 to work with - even if he didn't phrase it quite like that.

  • BernieBernie

    @radikalfilm

    I hear that! You're both right about the bigger point for sure of unnecessary log footage, it can indeed damage the image in a low contrast/ dynamic range environment when you're working with low bit rate & depth footage!

    I've seen manys a ruined shot from A7S footage shot at night in log, the colour goes to hell.

  • radikalfilmradikalfilm

    Related: Who here shoots Rec.2020 HLG? Does acquisition at UHD 8bit 420 Rec.2020 HLG (mouthful) hold up well enough? It's what my cam does, but I've yet to find time for testing.

  • Vitaliy_KiselevVitaliy_Kiselev

    @radikalfilm

    Shooting Rec.2020 in 8bit is especially bad. And HLG adds even more to it.

  • radikalfilmradikalfilm

    So you would recommend staying on Rec.709 for UHD 8bit 420? (it's what I do now) What about Rec.709+HLG (if that's even an option).

  • Vitaliy_KiselevVitaliy_Kiselev

    @radikalfilm

    420, 422 or 444 does not matter at all. Totally.

    HLG changes curve at highlights. So, until you plan to produce HDR content only using HLG, why use it?

  • radikalfilmradikalfilm

    I thought HLG enables both SDR and HDR content? One can export separate deliverables for each.

    The question remains about Rec.709+HLG when acquiring UHD at 8bit. You said Rec.2020 is bad at 8bit, and Rec.2020+HLG is worse.

    I would of course want to extend the dynamic range at acquisition and delivery. Rec.709 by itself holds only 6.5 stops.

  • Vitaliy_KiselevVitaliy_Kiselev

    @radikalfilm

    Situation with all this "stops" terms is extremely shitty complicated (and mixed by marketers among capture device, codec/container/gamma/space, and delivery device).

    If you really want to preserve info in highlights and do some real editing with it, shoot in 10bit log or such.

    Rec.709 by itself holds only 6.5 stops.

    Here it is required very detailed explanation that guys who write this mean. As with any gamma, if I output this image into TV with 8bit panel and 5000:1 contrast (good VA panel), will it be also 6.5 stops? How to calculate stops?

  • radikalfilmradikalfilm

    Vitaliy! My camera (PXW-Z90V) only does 8bit in UHD. It can do all the logs,hlg,Recs there are...all of them at 8bit. Very simply, what settings will allow for the widest dynamic range? Is there a straight answer to that? Thank you. (In HD it has10 bits, but I'm moving to UHD acquisition exclusively).

  • Vitaliy_KiselevVitaliy_Kiselev

    @radikalfilm

    Well, just make small test with log and HLG. And use them where you really need this highlights and high DR.

  • nomadnomad

    In about 99% of use cases, it doesn't make any sense to shoot log if you only have 8 bits of color depth for recording. Some of the worst are Sony's cameras in the A7 line, where some models even offer Slog3, which is far too flat for 8 bit, it would even be challenging 10 bit. But Slog2 isn't any better with its non-linearities, very hard to grade. Offering these in an 8-bit camera is sheer marketing, like "Your camera has the same profiles as the big boys use and you'll soon end up in the Hollywood hall of fame!". Only if you have a very demanding scene contrast it may be helpful, but in most situations you just waste bits, check your histogram or waveform. The Cine profiles, like Cine4, are making better use of your precious bit depth.

  • Vitaliy_KiselevVitaliy_Kiselev

    @nomad

    LOG popularity has two sources (outside manufacturer marketing and that it is easy to make)

    • Red compressed raw patents
    • NAND memory hikes

    Camera for such uses must have something like BM raw *that is designed to go around Red patents) at least and better - real good compressed raw.

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